Fragile X syndrome; Premature Ovarian Insufficiency; Fragile X Associated Tremor/Ataxia Syndrome; Martin Bell syndrome

FMR1-related disorders include fragile X syndrome, fragile X-associated tremor/ataxia syndrome (FXTAS), and FMR1-related premature ovarian insufficiency (POI). Fragile X syndrome is characterized by moderate intellectual disability in males and mild intellectual disability in affected females.  Males may also display a characteristic appearance, macroorchidism after puberty and behavioral abnormalities.  FXTAS may occur in males and, rarely, in females who have an FMR1 premutation, and is characterized by late-onset, progressive cerebellar ataxia and intention tremor.  FMR1-related POI occurs in approximately 20% of females who have an FRM1 premutation.

The FMR1-related disorders are caused by mutations in the FMR1 gene on the X-chromosome, the most common mutation being expansion of the CGG repeat in the 5′ untranslated region of exon 1. Repeat alleles in the FMR1 gene are classified in our lab as:

• Normal: ~5 to ~54 repeats
• Premutation: ~55 to ~200 repeats and unmethylated
• Full mutation: >200 repeats and methylated

More than 99% of individuals with fragile X syndrome have a loss-of-function mutation in the FMR1 gene caused by the expansion of CGG trinucleotide repeats into the full mutation range, which results in aberrant methylation of the FMR1 gene.

Other mutations in FMR1 that cause fragile X syndrome include deletions and point mutations that disrupt RNA splicing, and missense mutations. All individuals with FXTAS or FMR1-related POI have an FMR1 premutation.

1. Confirmation of diagnosis:
   1. Fragile X Syndrome: Individuals of either sex with global developmental delay (GDD) or intellectual disability (ID) of unknown etiology , or autism spectrum disorders (ASD).  Testing females with learning disabilites may also be considered.
   2. FXTAS: Patients over 50 years of age who have progressive cerebellar ataxia and intention tremor in whom other common causes of ataxia have been excluded.
   3. Premature Ovarian Insufficiency: Women with unexplained premature ovarian insufficiency or reproductive or fertility problems associated with an elevated follicle stimulating hormone (FSH) level in the postmenopausal range before the age of 40.
2. Carrier testing. 

   NB: Carriers have the potential for health problems (FXTAS or FMR1-related POI) in addition to the ability to transmit disease to offspring, therefore this testing in an asymptomatic individual is presymptomatic testing.

   1. Adults with a family history of fragile X syndrome, fragile X tremor/ataxia syndrome, or premature ovarian failure (in more than one family member) if the pedigree structure is consistent with X-linked inheritance and the individual is at risk of inheriting the mutated gene. Referral to a medical geneticist for counselling and assessment should be considered in these cases. 
   2. Adults who have at least one male relative with autism or mental retardation/developmental delay of an unknown etiology within a three-generation pedigree, if the pedigree structure is consistent with X-linked inheritance and the individual is at risk of inheriting the mutated gene. 
3. Prenatal testing (prenatal diagnosis requests are not normally accepted from physicians other than Medical Geneticists):
   1. Pregnancies of females known to have an FMR1 mutation.

Population-based carrier screening (i.e., screening in the absence of any other indication) is not covered by Health Insurance BC (BC MSP). Please contact MGL to discuss.

PCR amplification is performed across the CGG repeat region of the FMR1 gene to determine the repeat size.  In some cases, triplet-primed (tp) PCR (Amplidex PCR/CE FMR1 Reagents, Asuragen, Inc) is performed to assess for the presence of expanded alleles. This assay does not assess methylation status; however, in most cases the repeat is sized well into the full mutation range and, thus, hypermethylation can be assumed.  In rare cases, a repeat collection and testing by Southern blot analysis will be recommended.

 For more information, see FAQ

 Please note: MGL reports repeat sizes only when relevant for risk estimate counselling (i.e. premutation range from 55 – ~120 repeats); otherwise, repeats are categorized as normal, premutation, and full mutation only.

Pregnancy-related/Prenatal

If pregnancy management will be altered, 3 weeks; otherwise, routine TAT.

Blood: 4 mL EDTA is optimal (Minimum: 1 mL EDTA)
DNA: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth and ship to the address below. Samples should be shipped at room temperature with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays).  

Prenatal Specimens
Prenatal testing REQUIRES LABORATORY CONSULTATION PRIOR TO THE PROCEDURE and can only be ordered by a Medical Geneticist. Contact the laboratory at 604-875-2852 and choose the appropriate option for the Molecular Geneticist on service.
Chorionic Villi: 20 mg.
Direct Amniotic fluid: 25 mL collected in two separate tubes of equal volume.
Cultured Amniocytes: Two (2) 100% confluent T-25 flasks.
DNA extracted from prenatal specimens: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth. Ship samples by overnight courier with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays) as follows:

• Villi – on wet ice or in media at room temperature
• Amniocytes, Amniotic fluid, DNA – at room temperature

Testing is only available to residents of Canada, except in very specific circumstances where testing is urgent or emergent.  Payment is not required when requests are made for individuals who are insured by Health Insurance BC (administered through the BC Medical Services Plan (MSP)) AND eligible for testing according to the test utilization guidelines / policy. If the individual undergoing testing is not insured by these providers or does not meet utilization guidelines or policy, please complete a billing form; testing will only commence after receipt of billing informationTest prices can be found here.

Molecular genetic testing is limited by the current understanding of the genome and the genetics of a particular disease, as well as by the method of detection used.  This method will not detect all mutations (e.g., point mutations in the coding region of the gene, large genomic deletions, promoter mutations, regulatory element mutations). 

For carrier/predictive testing due to family history, it is generally important to first document the gene mutation in an affected or carrier family member.  Ideally, this information should be provided to the laboratory for assessment of whether the assay is appropriate for detection of the familial mutation, and to aid in the interpretation of data.

In certain scenarios of repeat size mosaicism, false negative results may occur.  If results obtained do not match the clinical findings, consult the on-service Molecular Geneticist.

Rare single nucleotide variants or polymorphisms could lead to false-negative results. If results obtained do not match the clinical findings, consult the on-service Molecular Geneticist.

A previous bone marrow transplant from an allogenic donor will result in molecular data that reflects the donor genotype rather than the recipient (patient) genotype.  Consult the on-service Molecular Geneticist for approach to testing in such individuals. 

Transfusions performed with packed red blood cells will generally not affect the outcome of molecular genetic testing.  However, if there is no clinical urgency, the cautious approach is to wait one week post-packed red cell transfusion before collecting a sample for genetic testing.  Consult the on-service Molecular Geneticist as needed.

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in our interpretation of results may occur if information given is inaccurate or incomplete.

Oculopharyngeal muscular dystrophy (OPMD) typically manifests after age 45 with ptosis and dysphagia.  Weakness often spreads to the tongue, facial muscles, and proximal extremities.  More severe cases (5% – 10%) have earlier onset and more pronounced involvement of the extremities.  There is usually a history of the disorder in one or more family members.

OPMD is caused by an expansion of the GCN trinucleotide repeat in exon 1 of the PABPN1 gene.  Normal repeat length is 10.  Expansions of 12 or more repeats are by themselves sufficient to cause disease and, therefore, account for the autosomal dominant inheritance observed in most families.  Autosomal recessive inheritance is observed in transmission of 11-repeat alleles (i.e. homozygotes are affected and heterozygotes are not).

1. Confirmation of diagnosis:
   1. In individuals with clinical features suggestive of OPMD.
2. Carrier testing:
   1. Individuals at risk to be carriers of the autosomal recessive allele (GCN)11 because of a family history of an individual confirmed to have autosomal recessive OMPD or to be a compound heterozygote for (GCN)12-17/(GCN)11.
3. Prenatal testing (technically feasible but not routinely performed – contact MGL to discuss):
   1. Pregnancies of couples at risk of having a child with OPMD due to known mutation(s).
4. Presymptomatic testing:
   1. Adults known to be at risk of developing OPMD because of a molecularly confirmed family history. Predictive testing will only be performed following genetic counselling by a recognized genetic service.

Sizing of the GCN repeat in the PABPN1 gene is carried out on an ABI genetic analyzer following fluorescence-based PCR amplification.

Blood: 4 mL EDTA is optimal (Minimum: 1 mL EDTA)
DNA: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth and ship to the address below. Samples should be shipped at room temperature with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays). 

Testing is only available to residents of Canada, except in very specific circumstances where testing is urgent or emergent.  Payment is not required when requests are made for individuals who are insured by Health Insurance BC (administered through the BC Medical Services Plan (MSP)) AND eligible for testing according to the test utilization guidelines / policy. If the individual undergoing testing is not insured by these providers or does not meet utilization guidelines or policy, please complete a billing form; testing will only commence after receipt of billing informationTest prices can be found here.

Molecular genetic testing is limited by the current understanding of the genome and the genetics of a particular disease, as well as by the method of detection used. This method will not detect all mutations (e.g., point mutations in the coding region of the gene, large genomic deletions, promoter mutations, regulatory element mutations). For some trinucleotide repeat disorders, repeat expansions have been described that cannot be amplified by PCR. Consideration should be given to this particularly in cases with severe clinical features or early onset; consult the on-service Molecular Geneticist to discuss specific repeat disorders.

For carrier/predictive testing due to family history, it is generally important to first document the gene mutation in an affected or carrier family member. This information should be provided to the laboratory for assessment of whether the assay is appropriate for detection of the familial mutation, and to aid in the interpretation of data.

In some cases, DNA alterations of undetermined or unclear clinical significance may be identified.

In certain scenarios of repeat size mosaicism, false negative results may occur. If results obtained do not match the clinical findings, consult the on-service Molecular Geneticist.

Rare single nucleotide variants or polymorphisms could lead to false-negative or false-positive results. If results obtained do not match the clinical findings, consult the on-service Molecular Geneticist.

A previous bone marrow transplant from an allogenic donor will result in molecular data that reflects the donor genotype rather than the recipient (patient) genotype. Consult the on-service Molecular Geneticist for approach to testing in such individuals.

Transfusions performed with packed red blood cells will generally not affect the outcome of molecular genetic testing. However, if there is no clinical urgency, the cautious approach is to wait one week post packed red cell transfusion before collecting a sample for genetic testing. Consult the on-service Molecular Geneticist as needed.

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in our interpretation of results may occur if information given is inaccurate or incomplete.

Duchenne Muscular Dystrophy; Becker Muscular Dystrophy; DMD-Related Dilated Cardiomyopathy

The dystrophinopathies manifest as a spectrum of muscle diseases. The mildest of the phenotypes includes an asymptomatic increase in serum concentration of creatine phosphokinase (CK or CpK), muscle cramps with myoglobinuria, and isolated quadriceps myopathy. At the opposite end of the spectrum is Duchenne muscular dystrophy (DMD), usually presenting in early childhood with delay in the motor milestones. DMD is rapidly progressive; patients are usually wheelchair-bound by 12 years of age and death usually occurs before age 30, due most frequently to respiratory complications and/or cardiomyopathy. Becker muscular dystrophy (BMD) is characterized by later-onset skeletal muscle weakness; individuals with BMD usually remain ambulatory well into their 20s. Despite the milder skeletal muscle involvement in BMD, cardiomypathy is a common cause of morbidity and the most common cause of death (on average in the mid-40s). Finally, DMD-associated dilated cardiomyopathy (DCM) is characterized by left ventricular dilation and congestive heart failure. Female carriers of DMD mutations are at increased risk for cardiomyopathy.

The dystrophinopathies are due to mutations in dystrophin (DMD), an X-linked gene encoding a membrane-associated protein that is found in muscle and a subset of neurons. The Duchenne phenotype is almost invariably caused by mutations that disrupt the reading frame including: deletions or duplications; nonsense mutations, and splice-site mutations. These produce a dystrophin protein molecule that is degraded. The milder Becker phenotype, on the other hand, results from mutations that reduce but do not completely eliminate the production of functional dystrophin protein, including deletions or duplications that maintain the open reading frame of the transcript, some splicing mutations, and most non-truncating single-base changes that result in translation of a protein product with intact N and C termini. DMD-associated dilated cardiomyopathy is caused by mutations in DMD that affect the muscle promoter (PM) and the first exon (E1), resulting in no dystrophin transcript being produced in cardiac muscle; expression (under different promoters) is retained in skeletal muscle and the central nervous system.

1. Confirmation of diagnosis:
   1. Testing of males with a suspected diagnosis of DMD.
   2. Testing of females is warranted if there is a clinical presentation consistent with the disease.
2. Carrier testing:
   1. Testing of adult females at risk to be carriers because of a family history. NB: Carriers have the potential for health problems in addition to the ability to transmit disease to offspring; genetic counselling is recommended prior to testing.
3. Prenatal testing (prenatal diagnosis requests are not normally accepted from physicians other than Medical Geneticists):
   1. Pregnancies at risk of inheriting a known DMD deletion or duplication. Prior to testing for the DMD mutation, fetal sexing is performed; if the fetus is female, further testing is not indicated.
      NB: If the mutation segregating in the mother is not known, consult the on-service Molecular Geneticist for assessment of whether linkage analysis is available for prenatal diagnosis
4. Presymptomatic testing:
   1. Requests for presymptomatic testing are only accepted following genetic counselling by a recognized genetic service.

Multiplex ligation-dependant probe amplification (MLPA) is carried out with the P034-A2 and P035-A2 probe mixes (MRC-Holland) to detect whole exon deletions and duplications; each of the 79 exons of DMD and the alternate exon 1 (DP427c) are assessed.

Pregnancy-related/Prenatal

If pregnancy management will be altered, 3 weeks; otherwise, routine TAT.

Blood: 4 mL EDTA is optimal (Minimum: 1 mL EDTA)
DNA: NOT ACCEPTED

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth and ship to the address below. Samples should be shipped at room temperature with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays). 

Prenatal Specimens
Prenatal testing REQUIRES LABORATORY CONSULTATION PRIOR TO THE PROCEDURE and can only be ordered by a Medical Geneticist. Contact the laboratory at 604-875-2852 and choose the appropriate option for the Molecular Geneticist on service.
Chorionic Villi: 20 mg.
Direct Amniotic fluid: 25 mL collected in two separate tubes of equal volume.
Cultured Amniocytes: Two (2) 100% confluent T-25 flasks.

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth. Ship samples by overnight courier with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays) as follows:

• Villi – on wet ice or in media at room temperature
• Amniocytes, Amniotic fluid, DNA – at room temperature

Testing is only available to residents of Canada, except in very specific circumstances where testing is urgent or emergent.  Payment is not required when requests are made for individuals who are insured by Health Insurance BC (administered through the BC Medical Services Plan (MSP)) AND eligible for testing according to the test utilization guidelines / policy. If the individual undergoing testing is not insured by these providers or does not meet utilization guidelines or policy, please complete a billing form; testing will only commence after receipt of billing informationTest prices can be found here.

Molecular genetic testing is limited by the current understanding of the genome and the genetics of a particular disease, as well as by the method of detection used. This method will not detect all mutations (e.g., point mutations in the coding region, promoter mutations, and regulatory element mutations). In rare cases, a point mutation could be detected.

For carrier/predictive testing due to family history, it is generally important to first document the gene mutation in an affected or carrier family member. This information should be provided to the laboratory for assessment of whether the assay is appropriate for detection of the familial mutation, and to aid in the interpretation of data.

In some cases, DNA alterations of undetermined or unclear clinical significance may be identified.

Rare single nucleotide variants or polymorphisms could lead to false-negative results. If results obtained do not match the clinical findings, consult the on-service Molecular Geneticist.

A previous bone marrow transplant from an allogenic donor will result in molecular data that reflects the donor genotype rather than the recipient (patient) genotype. Consult the on-service Molecular Geneticist for approach to testing in such individuals.

Transfusions performed with packed red blood cells will generally not affect the outcome of molecular genetic testing. However, if there is no clinical urgency, the cautious approach is to wait one week post packed red cell transfusion before collecting a sample for genetic testing. Consult the on-service Molecular Geneticist as needed.

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in our interpretation of results may occur if information given is inaccurate or incomplete.

Fragile X syndrome; Premature Ovarian Insufficiency; Fragile X Associated Tremor/Ataxia Syndrome; Martin Bell syndrome

FMR1-related disorders include fragile X syndrome, fragile X-associated tremor/ataxia syndrome (FXTAS), and FMR1-related premature ovarian insufficiency (POI). Fragile X syndrome is characterized by moderate intellectual disability in males and mild intellectual disability in affected females.  Males may also display a characteristic appearance, macroorchidism after puberty and behavioral abnormalities.  FXTAS may occur in males and, rarely, in females who have an FMR1 premutation, and is characterized by late-onset, progressive cerebellar ataxia and intention tremor.  FMR1-related POI occurs in approximately 20% of females who have an FRM1 premutation.

The FMR1-related disorders are caused by mutations in the FMR1 gene on the X-chromosome, the most common mutation being expansion of the CGG repeat in the 5′ untranslated region of exon 1. Repeat alleles in the FMR1 gene are classified in our lab as:

• Normal: ~5 to ~54 repeats
• Premutation: ~55 to ~200 repeats and unmethylated
• Full mutation: >200 repeats and methylated

More than 99% of individuals with fragile X syndrome have a loss-of-function mutation in the FMR1 gene caused by the expansion of CGG trinucleotide repeats into the full mutation range, which results in aberrant methylation of the FMR1 gene.

Other mutations in FMR1 that cause fragile X syndrome include deletions and point mutations that disrupt RNA splicing, and missense mutations. All individuals with FXTAS or FMR1-related POI have an FMR1 premutation.

1. Confirmation of diagnosis:
   1. Fragile X Syndrome: Individuals of either sex with global developmental delay (GDD) or intellectual disability (ID) of unknown etiology , or autism spectrum disorders (ASD).  Testing females with learning disabilites may also be considered.
   2. FXTAS: Patients over 50 years of age who have progressive cerebellar ataxia and intention tremor in whom other common causes of ataxia have been excluded.
   3. Premature Ovarian Insufficiency: Women with unexplained premature ovarian insufficiency or reproductive or fertility problems associated with an elevated follicle stimulating hormone (FSH) level in the postmenopausal range before the age of 40.
2. Carrier testing. 

   NB: Carriers have the potential for health problems (FXTAS or FMR1-related POI) in addition to the ability to transmit disease to offspring, therefore this testing in an asymptomatic individual is presymptomatic testing.

   1. Adults with a family history of fragile X syndrome, fragile X tremor/ataxia syndrome, or premature ovarian failure (in more than one family member) if the pedigree structure is consistent with X-linked inheritance and the individual is at risk of inheriting the mutated gene. Referral to a medical geneticist for counselling and assessment should be considered in these cases. 
   2. Adults who have at least one male relative with autism or mental retardation/developmental delay of an unknown etiology within a three-generation pedigree, if the pedigree structure is consistent with X-linked inheritance and the individual is at risk of inheriting the mutated gene. 
3. Prenatal testing (prenatal diagnosis requests are not normally accepted from physicians other than Medical Geneticists):
   1. Pregnancies of females known to have an FMR1 mutation.

Population-based carrier screening (i.e., screening in the absence of any other indication) is not covered by Health Insurance BC (BC MSP). Please contact MGL to discuss.

PCR amplification is performed across the CGG repeat region of the FMR1 gene to determine the repeat size.  In some cases, triplet-primed (tp) PCR (Amplidex PCR/CE FMR1 Reagents, Asuragen, Inc) is performed to assess for the presence of expanded alleles. This assay does not assess methylation status; however, in most cases the repeat is sized well into the full mutation range and, thus, hypermethylation can be assumed.  In rare cases, a repeat collection and testing by Southern blot analysis will be recommended.

 For more information, see FAQ

 Please note: MGL reports repeat sizes only when relevant for risk estimate counselling (i.e. premutation range from 55 – ~120 repeats); otherwise, repeats are categorized as normal, premutation, and full mutation only.

Pregnancy-related/Prenatal

If pregnancy management will be altered, 3 weeks; otherwise, routine TAT.

Blood: 4 mL EDTA is optimal (Minimum: 1 mL EDTA)
DNA: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth and ship to the address below. Samples should be shipped at room temperature with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays).  

Prenatal Specimens
Prenatal testing REQUIRES LABORATORY CONSULTATION PRIOR TO THE PROCEDURE and can only be ordered by a Medical Geneticist. Contact the laboratory at 604-875-2852 and choose the appropriate option for the Molecular Geneticist on service.
Chorionic Villi: 20 mg.
Direct Amniotic fluid: 25 mL collected in two separate tubes of equal volume.
Cultured Amniocytes: Two (2) 100% confluent T-25 flasks.
DNA extracted from prenatal specimens: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth. Ship samples by overnight courier with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays) as follows:

• Villi – on wet ice or in media at room temperature
• Amniocytes, Amniotic fluid, DNA – at room temperature

Testing is only available to residents of Canada, except in very specific circumstances where testing is urgent or emergent.  Payment is not required when requests are made for individuals who are insured by Health Insurance BC (administered through the BC Medical Services Plan (MSP)) AND eligible for testing according to the test utilization guidelines / policy. If the individual undergoing testing is not insured by these providers or does not meet utilization guidelines or policy, please complete a billing form; testing will only commence after receipt of billing informationTest prices can be found here.

Molecular genetic testing is limited by the current understanding of the genome and the genetics of a particular disease, as well as by the method of detection used.  This method will not detect all mutations (e.g., point mutations in the coding region of the gene, large genomic deletions, promoter mutations, regulatory element mutations). 

For carrier/predictive testing due to family history, it is generally important to first document the gene mutation in an affected or carrier family member.  Ideally, this information should be provided to the laboratory for assessment of whether the assay is appropriate for detection of the familial mutation, and to aid in the interpretation of data.

In certain scenarios of repeat size mosaicism, false negative results may occur.  If results obtained do not match the clinical findings, consult the on-service Molecular Geneticist.

Rare single nucleotide variants or polymorphisms could lead to false-negative results. If results obtained do not match the clinical findings, consult the on-service Molecular Geneticist.

A previous bone marrow transplant from an allogenic donor will result in molecular data that reflects the donor genotype rather than the recipient (patient) genotype.  Consult the on-service Molecular Geneticist for approach to testing in such individuals. 

Transfusions performed with packed red blood cells will generally not affect the outcome of molecular genetic testing.  However, if there is no clinical urgency, the cautious approach is to wait one week post-packed red cell transfusion before collecting a sample for genetic testing.  Consult the on-service Molecular Geneticist as needed.

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in our interpretation of results may occur if information given is inaccurate or incomplete.

Familial Mediterranean Fever; Recurrent Polyserositis; Familial Paroxysmal Polyserositis; Familial Periodic Fever; TNF receptor-associated periodic syndrome; TRAPS; Familial Hibernian Fever; Autosomal dominant periodic fever syndrome; Hyper-IgD syndrome; Mevalonate Kinase Deficiency; Periodic Fever, Dutch Type; Hypergammaglobulinemia D and periodic fever syndrome

The periodic fever syndromes are disorders of the innate immune system characterized by recurrent episodes of inflammation and fever. The periodic fever syndromes may be inherited or acquired; the hereditary syndromes include familial Mediterranean fever (FMF), TNF receptor-associated periodic syndrome (TRAPS) and hyperimmunoglobulin D syndrome (HIDS), among others.

Familial Mediterranean Fever (FMF) in its classic form (Type 1) is characterized by recurrent episodes of inflammation and serositis including fever, peritonitis, synovitis, pleuritis, and, rarely, pericarditis and meningitis. Amyloidosis, which can lead to renal failure, is the most severe complication. Amyloidosis is the first clinical manifestation in Type 2 FMF. The disorder predominantly affects individuals of Mediterranean descent, particularly North African Jews.

TNF receptor-associated periodic syndrome (TRAPS) is most frequently characterized by recurrent fevers (seen in 95% of cases); arthralgia/myalgia and abdominal pain are also common symptoms. Approximately 15% of individuals with TRAPS eventually go on to develop amyloidosis. The conditions typically presents in early childhood, although this, like the clinical symptoms, is highly variable, both within and between families.

Hyperimmunoglobulin D Syndrome (HIDS) is characterized by recurrent episodes of fever, gastrointestinal symptoms and lymphadenopathy. Individuals often have a high serum immunoglobulin D (IgD) and immunoglobulin A (IgA), and these remain elevated even in the absence of symptoms. The disorder mainly affects individuals with ancestry that can be traced to Northwestern Europe, although it has been reported in other ethnic groups.

FMF is an autosomal recessive disorder caused by mutations in the MEFV gene. MEFV is expressed exclusively in granulocytes and encodes pyrin, a protein critical in regulating the immune response.

TRAPS is an autosomal dominant condition caused by mutations in the TNFRSF1A gene, a member of the TNF-receptor superfamily. Most mutations are found in exons 2 to 4, and around 50% are substitutions of highly conserved cysteines in the extracellular domain. The exact mechanism by which mutations in TNFRSF1A cause TRAPS remains unclear, but most theories suggest that mutations lead to excess TNFR1 signalling. The majority of mutations are highly penetrant, but two recurrent variants (p.Pro46Leu and p.Arg92Gln) that can be seen in patients with milder symptoms of TRAPS can also be seen in healthy individuals.

HIDS is an autosomal recessive disease caused by mutations in the MVK gene. MVK encodes mevalonate kinase, an enzyme in the cholesterol, farnasyl and isoprenoid biosynthesis pathway. Most mutations in MVK that cause HIDS are missense variants that cause a reduction of MVK activity; however, more severe mutations that cause a near complete reduction in MVK activity cause the much more severe condition, mevalonic aciduria.

NOTE: TRAPS and HIDS may only be ordered or must be recommended* by a rheumatologist. 

        *consult letter must be provided

1. Confirmation of diagnosis:

       a.  In individuals with clinical features suggestive of FMF, TRAPS and/or HIDS.

2. Carrier testing

       a.  FMF and HIDS: Adults at risk to be carriers of either FMF or HIDS due to a family history confirmed with molecular testing.

3. Prenatal testing (technically feasible but not routinely performed – contact MGL to discuss):

       a.  Pregnancies known to be at risk of FMF, TRAPS or HIDS due to a family history. The mutation(s) segregating in the family must be known.

4. Presymptomatic testing:

       a.  Individuals at risk to have FMF, TRAPS or HIDS due to a family history of the condition. The mutation(s) segregating in the family must be known. Genetic counseling is recommended prior to presymptomatic testing.

Bi-directional Sanger sequencing across coding regions and flanking intronic sequences of the MEFV, TNFRSF1A and MVK genes.

In cases where FMF, TRAPS, and/or HIDS are requested for the same patient and priority of testing is not indicated, testing will proceed sequentially, starting with FMF. If FMF testing is negative, testing for TRAPS will be performed, followed by testing for HIDS.

MEFV: NM_000243.2

TNFRSF1A: NM_001065.2

MVK: NM_000431.2

The ‘A’ within the initiation codon, ATG, is designated as nucleotide number 1.

Blood: 4 mL EDTA is optimal (Minimum: 1 mL EDTA)
DNA: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth and ship to the address below. Samples should be shipped at room temperature with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays). 

Testing is only available to residents of Canada, except in very specific circumstances where testing is urgent or emergent.  Payment is not required when requests are made for individuals who are insured by Health Insurance BC (administered through the BC Medical Services Plan (MSP)) AND eligible for testing according to the test utilization guidelines / policy. If the individual undergoing testing is not insured by these providers or does not meet utilization guidelines or policy, please complete a billing form; testing will only commence after receipt of billing informationTest prices can be found here.

Molecular genetic testing is limited by the current understanding of the genome and the genetics of a particular disease, as well as by the method of detection used. This method will not detect all mutations (e.g., large genomic deletions/duplications, promoter mutations, regulatory element mutations).

For carrier/predictive testing due to a family history, it is generally important to first document the gene mutation in an affected or carrier family member. This information should be provided to the laboratory for assessment of whether the assay is appropriate for detection of the familial mutation, and to aid in the interpretation of data.

In some cases, DNA alterations of undetermined or unclear clinical significance may be identified.

Rare single nucleotide variants or polymorphisms could lead to false-negative results. If results obtained do not match the clinical findings, consult the on-service Molecular Geneticist.

A previous bone marrow transplant from an allogenic donor will result in molecular data that reflects the donor genotype rather than the recipient (patient) genotype. Consult the on-service Molecular Geneticist for approach to testing in such individuals.

Transfusions performed with packed red blood cells will generally not affect the outcome of molecular genetic testing. However, if there is no clinical urgency, the cautious approach is to wait one week post packed red cell transfusion before collecting a sample for genetic testing. Consult the on-service Molecular Geneticist as needed.

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in our interpretation of results may occur if information given is inaccurate or incomplete.

Hemoglobin H Disease; Hydrops Fetalis; Alpha Thalassemia Minor; Alpha Thalassemia Trait; Thalassemia Intermedia; Cooley’s Anemia; Mediterranean Anemia; Beta Thalassemia Major; Beta Thalassemia Minor; Beta Thalassemia Trait; Sickle Cell Disease; Sickle Cell Anemia; Hemoglobin C Trait; Hemoglobin E Trait

Thalassemias and hemoglobinopathies are conditions affecting the quantity and functionality, respectively, of hemoglobin within red blood cells.

The thalassemias are the result of mutations that decrease or eliminate the production of individual globin chains of the hemoglobin tetramer.

The sickle cell disorders are hemoglobinopathies caused by specific point mutations in the β globin gene (hemoglobins S, C, and E) that result in structural abnormalities of the protein rather than decreased production.  The clinical features of the sickle disorders can be quite variable, depending in part on the particular number and combination of α globin mutations.

In addition, since both the α- and β-globin chains comprise the primary adult hemoglobin, the co-inheritance of β globin gene mutations (for either thalassemia or hemoglobinopathies) and α globin mutations (for thalassemia) further increases the clinical variability encountered in this group of disorders.

Alpha thalassemia

Alpha thalassemia typically results from deletion of one or more of the four α globin genes.  Rare point mutations may also contribute to the condition.

Beta thalassemia

Beta thalassemia results most commonly from point mutations that lead to a reduction or complete loss of protein synthesis from one or both β globin genes.

Sickling disorders

The sickling disorders are the result of single point mutations in the β globin gene that result in the production of abnormal β globin chains.  HbS, the hemoglobin that causes sickle cell disease when present in the homozygous state, is caused by a p.Glu6Val β globin substitution (c.20A>T).  HbC is caused by a p.Glu6Lys (c.19G>A) β globin substitution .  HbE is caused by a p.Glu26Lys (c.79G>A) β globin substitution.  Notably, the HbE mutation results in the activation of a cryptic donor splice site, resulting in a thalassemia phenotype when co-inherited with another beta thalassemia mutation.

Other hemoglobinopathies result from various combinations of alpha and/or beta globin mutations as well as the other globin chain genes.

A hematology profile, including CBC and hemoglobin electrophoresis/HPLC, must be performed prior to ordering molecular genetic testing for the hemoglobin disorders unless an individual has a clinical diagnosis of one of the hemoglobin disorders.  If hematology investigations require follow up with molecular genetic testing, then these tests may be ordered.

1. Confirmation of diagnosis: 
   1. Testing ordered by a hematologist as relevant to the clinical presentation of the patient; to confirm a suspected or known clinical diagnosis or clarify unusual hemoglobinopathy cases.
2. Carrier testing:
   1. When ordered by a hematologist: as relevant to the clinical presentation/management of disease of the patient.
   2. Pediatric patients: to aid in the discrimination of carrier status from iron deficiency anemia.
   3. Adults of reproductive age: as per the SOGC-CCMG clinical practice guideline (2008).
   4. Specific for alpha thalassemia:
      1. In adults of reproductive age when:
         1. Both members of the couple have beta thalassemia trait and they may also be at risk of conceiving a child with Hemoglobin Barts hydrops fetalis syndrome.
         2. One member of the couple has beta thalassemia trait and the other has hematology suggestive of alpha thalassemia trait (i.e. their pregnancy may also be at risk of Hb Barts/hydrops fetalis)
      2. NB: Carrier screening to determine the reproductive risk for HbH disease is NOT an indication for molecular genetic testing that is eligible for coverage by BC MSP unless one member of the couple has hematology consistent with alpha thalassemia trait and the other has HPLC findings consistent with the HBA2 Constant Spring or Quong Sze mutations.
3. Prenatal testing (prenatal diagnosis requests are not normally accepted from physicians other than Medical Geneticists):
   1. Pregnancies known to be at risk based on parental carrier screening or ultrasound findings.

Carrier screening to determine the reproductive risk for HbH disease is NOT an indication for molecular genetic testing for alpha thalassemia except where one member of the couple has hematology consistent with alpha thalassemia trait and the other has HPLC findings consistent with a pathogenic HBA1 or HBA2 mutation (for example, hemoglobin Constant Spring). Genetic counselling is required prior to testing for couples in this scenario.

Alpha thalassemia: Gap junction PCR analysis is carried out to detect the –SEA, -α20.5, –MED, –FIL, –THAI, -α3.7, and -α4.2 deletions. Bidirectional Sanger sequencing across the region of the alpha-2 gene (HBA2) that contains the Constant Spring (c.427T>C, p.*143GlnextX32) and Quong Sze (c.377T>C, p.Leu126Pro) mutations is not routinely performed, but is available in certain clinical scenarios; consult on-service Molecular Geneticist.

Beta thalassemia & Hemoglobins S, C, E: Bidirectional Sanger sequencing across all exons of the HBB gene and intron sequences flanking each exon (exon 1: c.-105 to c.92+10; exon 2: c.93-25 to c.315+25; exon 3: c.316-200 to c*110). 

HBA: NM_000517.4  The ‘A’ within the initiation codon, ATG, is designated as nucleotide number 1.

HBB: NM_000518.4  The ‘A’ within the initiation codon, ATG, is designated as nucleotide number 1.

Pregnancy-related/Prenatal

If pregnancy management will be altered, 3 weeks; otherwise, routine TAT.

Blood: 4 mL EDTA is optimal (Minimum: 1 mL EDTA)
DNA: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth and ship to the address below. Samples should be shipped at room temperature with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays).  

Prenatal Specimens
Prenatal testing REQUIRES LABORATORY CONSULTATION PRIOR TO THE PROCEDURE and can only be ordered by a Medical Geneticist. Contact the laboratory at 604-875-2852 and choose the appropriate option for the Molecular Geneticist on service.
Chorionic Villi: 20 mg.
Direct Amniotic fluid: 25 mL collected in two separate tubes of equal volume.
Cultured Amniocytes: Two (2) 100% confluent T-25 flasks.
DNA extracted from prenatal specimens: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth. Ship samples by overnight courier with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays) as follows:

• Villi – on wet ice or in media at room temperature
• Amniocytes, Amniotic fluid, DNA – at room temperature

A hematology profile, including CBC and hemoglobin electrophoresis/HPLC MUST accompany the sample and requisition or be faxed separately to MGL when ordering testing for any of the hemoglobin disorders.

Testing is only available to residents of Canada, except in very specific circumstances where testing is urgent or emergent.  Payment is not required when requests are made for individuals who are insured by Health Insurance BC (administered through the BC Medical Services Plan (MSP)) AND eligible for testing according to the test utilization guidelines / policy. If the individual undergoing testing is not insured by these providers or does not meet utilization guidelines or policy, please complete a billing form; testing will only commence after receipt of billing informationTest prices can be found here.

Molecular genetic testing is limited by the current understanding of the genome and the genetics of a particular disease, as well as by the method of detection used.

Rare single nucleotide variants or polymorphisms could lead to false-negative or false-positive results. If results obtained do not match the clinical findings, consult the on-service Molecular Geneticist.

A previous bone marrow transplant from an allogenic donor will result in molecular data that reflects the donor genotype rather than the recipient (patient) genotype. Consult the on-service Molecular Geneticist for approach to testing in such individuals.

Transfusions performed with packed red blood cells will generally not affect the outcome of molecular genetic testing. However, if there is no clinical urgency, the cautious approach is to wait one week post packed red cell transfusion before collecting a sample for genetic testing. Consult the on-service Molecular Geneticist as needed.

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in our interpretation of results may occur if information given is inaccurate or incomplete.

Friedreich ataxia (FRDA) is characterized by slowly progressive ataxia, typically arising in late childhood or early adolescence. Common features include dysarthria, muscle weakness, spasticity in the lower limbs, scoliosis, bladder dysfunction, absent lower limb reflexes, and loss of position and vibration sense. Cardiomyopathy and diabetes mellitus are relatively common.

FRDA is an autosomal recessive condition caused by biallelic pathogenic variants of the frataxin (FXN) gene on chromosome 9q13.  Approximately 95% of patients with Friedreich ataxia are homozygous for an FXN GAA-repeat expansion; the remaining patients are compound heterozygotes for an FXN GAA-repeat expansion and either an inactivating point mutation or deletion of FXN.  To date, no affected individuals with two non-GAA triplet repeat mutations have been reported.

GAA repeat lengths are classified according to their phenotypic expression:

• Normal alleles: 5 – 33 repeats
• Mutable normal allels: 34 – ~65 repeats

The exact boundary between normal and full penetrance alleles has not been determined; alleles at the boundary are assessed further.

• Full penetrance (expanded) alleles: ~66 repeats or greater

1. Confirmation of diagnosis:
   1. In individuals with clinical features suggestive of Friedreich Ataxia.
2. Carrier testing:
   1. Adults at risk to be carriers because of a family history of FRDA.
3. Prenatal testing: (technically feasible, but rarely performed – contact MGL to discuss):
   1. Pregnancies known to be at risk of FRDA and the mutations are known.
4. Presymptomatic testing:
   1. Requests to test asymptomatic children who are at risk of developing FRDA are only accepted following genetic counselling by a recognized genetic service.

PCR and triplet-primed (tp) PCR amplification is performed across the GAA repeat region of the FXN gene to assess for normal and expansion allelles.  

For more information, see FAQ

Blood: 4 mL EDTA is optimal (Minimum: 1 mL EDTA)
DNA: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth and ship to the address below. Samples should be shipped at room temperature with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays). 

Testing is only available to residents of Canada, except in very specific circumstances where testing is urgent or emergent.  Payment is not required when requests are made for individuals who are insured by Health Insurance BC (administered through the BC Medical Services Plan (MSP)) AND eligible for testing according to the test utilization guidelines / policy. If the individual undergoing testing is not insured by these providers or does not meet utilization guidelines or policy, please complete a billing form; testing will only commence after receipt of billing informationTest prices can be found here.

Molecular genetic testing is limited by the current understanding of the genome and the genetics of a particular disease, as well as by the method of detection used. This method will not detect all mutations (e.g., point mutations in the coding region of the gene, large genomic deletions, promoter mutations, regulatory element mutations). For some trinucleotide repeat disorders, repeat expansions have been described that cannot be amplified by PCR. Consideration should be given to this particularly in cases with severe clinical features or early onset; consult the on-service Molecular Geneticist to discuss specific repeat disorders.

For carrier/predictive testing due to family history, it is generally important to first document the gene mutation in an affected or carrier family member. This information should be provided to the laboratory for assessment of whether the assay is appropriate for detection of the familial mutation, and to aid in the interpretation of data.

In some cases, DNA alterations of undetermined or unclear clinical significance may be identified.

In certain scenarios of repeat size mosaicism, false negative results may occur. If results obtained do not match the clinical findings, consult the on-service Molecular Geneticist.

Rare single nucleotide variants or polymorphisms could lead to false-negative or false-positive results. If results obtained do not match the clinical findings, consult the on-service Molecular Geneticist.

A previous bone marrow transplant from an allogenic donor will result in molecular data that reflects the donor genotype rather than the recipient (patient) genotype. Consult the on-service Molecular Geneticist for approach to testing in such individuals.

Transfusions performed with packed red blood cells will generally not affect the outcome of molecular genetic testing. However, if there is no clinical urgency, the cautious approach is to wait one week post packed red cell transfusion before collecting a sample for genetic testing. Consult the on-service Molecular Geneticist as needed.

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in our interpretation of results may occur if information given is inaccurate or incomplete.

Prader-Labhart-Willi Syndrome

Prader-Willi syndrome (PWS) is characterized by severe hypotonia and feeding difficulties in early infancy, followed later by excessive eating which, if uncontrolled, leads to the gradual development of morbid obesity. Developmental delay and cognitive impairment occur in all affected individuals. A distinctive behavioral phenotype is often seen as the individual matures. Hypogonadism is present in both males and females.

PWS is caused by abnormal imprinting in the Prader-Willi critical region (15q11.2-q13) that results in the loss of paternal expression of critical genes in the region. This loss of paternal expression can occur by one of several different known genetic mechanisms: paternal deletion in the region; maternal uniparental disomy (UPD) for chromosome 15; or abnormal imprinting. In all cases, an abnormal methylation pattern will be observed in the 15q11.2-q13 region.

1. Confirmation of diagnosis: This test should be used as the first line diagnostic test in a child with a suspected clinical diagnosis of PWS as it provides information regarding methylation, regardless of underlying mechanism. See test algorithm for further details.
2. Prenatal testing (prenatal diagnosis requests are not normally accepted from physicians other than Medical Geneticists):
   1. In pregnancies at risk of PWS.

Pregnancy-related/Prenatal

If pregnancy management will be altered, 3 weeks; otherwise, routine TAT.

Blood: 4 mL EDTA is optimal (Minimum: 1 mL EDTA)
DNA: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth and ship to the address below. Samples should be shipped at room temperature with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays).  

Prenatal Specimens
Prenatal testing REQUIRES LABORATORY CONSULTATION PRIOR TO THE PROCEDURE and can only be ordered by a Medical Geneticist. Contact the laboratory at 604-875-2852 and choose the appropriate option for the Molecular Geneticist on service.
Chorionic Villi: 20 mg.
Direct Amniotic fluid: 25 mL collected in two separate tubes of equal volume.
Cultured Amniocytes: Two (2) 100% confluent T-25 flasks.
DNA extracted from prenatal specimens: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth. Ship samples by overnight courier with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays) as follows:

• Villi – on wet ice or in media at room temperature
• Amniocytes, Amniotic fluid, DNA – at room temperature

Testing is only available to residents of Canada, except in very specific circumstances where testing is urgent or emergent.  Payment is not required when requests are made for individuals who are insured by Health Insurance BC (administered through the BC Medical Services Plan (MSP)) AND eligible for testing according to the test utilization guidelines / policy. If the individual undergoing testing is not insured by these providers or does not meet utilization guidelines or policy, please complete a billing form; testing will only commence after receipt of billing informationTest prices can be found here.

Molecular genetic testing is limited by the current understanding of the genome and the genetics of a particular disease, as well as by the method of detection used.

Rare single nucleotide variants or polymorphisms could lead to false-negative or false-positive results. If results obtained do not match the clinical findings, consult the on-service Molecular Geneticist.

A previous bone marrow transplant from an allogenic donor will result in molecular data that reflects the donor genotype rather than the recipient (patient) genotype. Consult the on-service Molecular Geneticist for approach to testing in such individuals.

Transfusions performed with packed red blood cells will generally not affect the outcome of molecular genetic testing. However, if there is no clinical urgency, the cautious approach is to wait one week post packed red cell transfusion before collecting a sample for genetic testing. Consult the on-service Molecular Geneticist as needed.

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in our interpretation of results may occur if information given is inaccurate or incomplete.

Sudden Unexplained Nocturnal Death Syndrome; SUNDS

Brugada Syndrome is a cardiac conduction abnormality characterized by malignant ventricular arrhythmias, usually in an adult who reports a history of syncopal episodes. Sudden death is not uncommon. Classic cases have a typical ECG pattern, characterized by coved-type ST-segment elevation in the right precordial leads (so-called “type 1 Brugada ECG”), along with a personal history arrhythmia and/or a family history of premature sudden cardiac death or the characteristic ECG pattern.

Autosomal dominant inheritance with reduced penetrance. The primary gene associated with Brugada syndrome is SCN5A; mutations are identified in 15 to 30% of cases of individuals with type 1 Brugada ECG. Fewer than 5% of cases are accounted for by mutations in one of at least 11 other additional genes. 

NOTE: for BC patients, criteria must be met in order for testing to proceed.

1. Confirmation of diagnosis:

a. Persistent or provocable type I Brugada ECG pattern (ST elevation of a cove-shaped pattern in leads VI and V2); AND

• identified by EP Cardiologist (a cardiologist with further certification/training in cardiac electrophysiology);
• no structural heart disease
• no drugs known to cause Brugada-like ECG pattern

b. Test requested by Cardiologist or Medical Geneticist;

2. Family Testing:

• SCN5A mutation identified in index case
• First-degree relative (parent, sibling, child) of index case or other mutation-positive family member;
• Test requested by Medical Geneticist or Cardiologist

3. Prenatal testing (technically feasible but not routinely performed – contact MGL to discuss):

• Pregnancies to couples in which one person has confirmed Brugada syndrome and a known SCN5A mutation.
• Test requested by Medical Genetics

Bidirectional Sanger sequencing of the entire coding region and flanking intronic sequences of the SCN5A gene.

NM_198056.2 The ‘A’ within the initiation codon, ATG, is designated as nucleotide number 1.

Blood: 4 mL EDTA is optimal (Minimum: 1 mL EDTA)
DNA: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth and ship to the address below. Samples should be shipped at room temperature with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays). 

Testing is only available to residents of Canada, except in very specific circumstances where testing is urgent or emergent.  Payment is not required when requests are made for individuals who are insured by Health Insurance BC (administered through the BC Medical Services Plan (MSP)) AND eligible for testing according to the test utilization guidelines / policy. If the individual undergoing testing is not insured by these providers or does not meet utilization guidelines or policy, please complete a billing form; testing will only commence after receipt of billing informationTest prices can be found here.

Molecular genetic testing is limited by the current understanding of the genome and the genetics of a particular disease, as well as by the method of detection used. This method will not detect all mutations (e.g., large genomic deletions/duplications, promoter mutations, regulatory element mutations).

For carrier/predictive testing due to a family history, it is generally important to first document the gene mutation in an affected or carrier family member. This information should be provided to the laboratory for assessment of whether the assay is appropriate for detection of the familial mutation, and to aid in the interpretation of data.

In some cases, DNA alterations of undetermined or unclear clinical significance may be identified.

Rare single nucleotide variants or polymorphisms could lead to false-negative results. If results obtained do not match the clinical findings, consult the on-service Molecular Geneticist.

A previous bone marrow transplant from an allogenic donor will result in molecular data that reflects the donor genotype rather than the recipient (patient) genotype. Consult the on-service Molecular Geneticist for approach to testing in such individuals.

Transfusions performed with packed red blood cells will generally not affect the outcome of molecular genetic testing. However, if there is no clinical urgency, the cautious approach is to wait one week post packed red cell transfusion before collecting a sample for genetic testing. Consult the on-service Molecular Geneticist as needed.

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in our interpretation of results may occur if information given is inaccurate or incomplete.

Glucose Transporter Protein Syndrome

Glucose transporter type 1 deficiency syndrome (Glut1-DS) typically presents in early infancy with seizures refractory to anticonvulsants, a variety of additional neurological manifestations (e.g., spasticity, ataxia), deceleration of head growth, and delays in mental and motor development.

Glut1-DS is an autosomal dominant condition caused by mutations in the SLC2A1 gene, the only gene known to be associated with this disorder. Probands with Glut1-DS often have the condition as a result of a de novo mutation.

1. Confirmation of diagnosis: 
   All 3 of the criteria below (a, b and c) must be met to request diagnostic testing. 
   A completed Glut1-DS Supplemental Information Form must be received before testing will proceed.
   1. GLUT1-DS Phenotype:
      1. Classical
         1. Epilepsy (particularly if refractory to ≥ 2 anti-epileptic drugs)
            AND
            Developmental delay / intellectual disability 
      2. Atypical
         1. Absence seizures with early onset (< 4 years of age)
            OR 
         2. Paroxysmal exercise-induced dyskinesia
            OR 
         3. Ataxia and/or hyperkinetic movement disorder
            AND
            Developmental delay / intellectual disability
            AND
            One or more of: epilepsy, migraine, microcephaly, positive family history
   2. CSF glucose ≤ 2.5 mmol/L AND CSF:fasting serum glucose ratio < 0.6
   3. Test requested by a Neurologist or a Biochemical Diseases specialist.

      Cases that do not meet all criteria may be reviewed with Dr. Michelle Demos (mdemos[at]cw.bc.ca) or Dr. Sylvia Stockler (sstockler[at]cw.bc.ca) for further consideration.  
       

2. Carrier testing: 
   1. Although this is an autosomal dominant condition, carrier testing may be relevant to identify non-penetrant / variably-expressive mutation carriers. The familial mutation must be known.
       
3. Prenatal testing (prenatal diagnosis requests are not normally accepted from physicians other than Medical Geneticists):
   1. Pregnancies at risk of GLUT1-DS and the familial mutation is known.

Bidirectional Sanger sequencing of the entire coding region and flanking intronic sequences of the SLC2A1 gene. Deletion/duplication analysis of SLC2A1 (by multiplex ligation-probe amplification – MLPA) is performed if sequencing is negative.

NM_006516.2 The ‘A’ within the initiation codon, ATG, is designated as nucleotide number 1.

Pregnancy-related/Prenatal

If pregnancy management will be altered, 3 weeks; otherwise, routine TAT.

Blood: 4 mL EDTA is optimal (Minimum: 1 mL EDTA)
DNA: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)

NOTE: DNA is only accepted for requests for sequencing analysis.  If MLPA is required, EDTA blood must be collected.

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth and ship to the address below. Samples should be shipped at room temperature with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays). 

Prenatal Specimens
Prenatal testing REQUIRES LABORATORY CONSULTATION PRIOR TO THE PROCEDURE and can only be ordered by a Medical Geneticist. Contact the laboratory at 604-875-2852 and choose the appropriate option for the Molecular Geneticist on service.
Chorionic Villi: 20 mg.
Direct Amniotic fluid: 25 mL collected in two separate tubes of equal volume.
Cultured Amniocytes: Two (2) 100% confluent T-25 flasks.
DNA extracted from prenatal specimens: 100 μL at 200 ng/μL is optimal (Minimum: 30 μL at 200 ng/μL)

Label each sample with three patient identifiers; preferably patient name, PHN, and date of birth. Ship samples by overnight courier with a completed MGL Requisition to arrive Monday to Friday (not on Canadian statutory holidays) as follows:

• Villi – on wet ice or in media at room temperature
• Amniocytes, Amniotic fluid, DNA – at room temperature

A completed Glut1-DS Supplemental Information Form MUST accompany the requisition. 

Testing is only available to residents of Canada, except in very specific circumstances where testing is urgent or emergent.  Payment is not required when requests are made for individuals who are insured by Health Insurance BC (administered through the BC Medical Services Plan (MSP)) AND eligible for testing according to the test utilization guidelines / policy. If the individual undergoing testing is not insured by these providers or does not meet utilization guidelines or policy, please complete a billing form; testing will only commence after receipt of billing informationTest prices can be found here.

Molecular genetic testing is limited by the current understanding of the genome and the genetics of a particular disease, as well as by the method of detection used. This method will not detect all mutations (e.g., promoter mutations, regulatory element mutations).

For carrier/predictive testing due to family history, it is generally important to first document the gene mutation in an affected or carrier family member. This information should be provided to the laboratory for assessment of whether the assay is appropriate for detection of the familial mutation, and to aid in the interpretation of data.

In some cases, DNA alterations of undetermined or unclear clinical significance may be identified.

Rare single nucleotide variants or polymorphisms could lead to false-negative results. If results obtained do not match the clinical findings, consult the on-service Molecular Geneticist.

A previous bone marrow transplant from an allogenic donor will result in molecular data that reflects the donor genotype rather than the recipient (patient) genotype. Consult the on-service Molecular Geneticist for approach to testing in such individuals.

Transfusions performed with packed red blood cells will generally not affect the outcome of molecular genetic testing. However, if there is no clinical urgency, the cautious approach is to wait one week post packed red cell transfusion before collecting a sample for genetic testing. Consult the on-service Molecular Geneticist as needed.

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in our interpretation of results may occur if information given is inaccurate or incomplete.