Familial Amyloid Cardiomyopathy; Familial Amyloid Polyneuropathy; Leptomeningeal Amyloidosis; Familial Oculoleptomeningeal Amyloidosis

Transthyretin (TTR) amyloidosis is characterized by a slowly progressive neuropathy and other problems associated with amyloid deposition in the heart, kidney, eye, and central nervous system. The disorder has a particularly high prevalence in Japan and Portugal, where onset is earlier (between ages 20 and 40) than in other regions. Reduced and age-related penetrance is observed, as well as variable expressivity. A small number of genotype-phenotype correlations have been documented.

TTR amyloidosis is an autosomal dominant condition caused exclusively by mutations in the TTR gene. The most frequent mutation, p.Val30Met, has been reported in individuals from many different ethnic backgrounds and is particularly common among Japanese, Portugese, and Swedish cases. Point mutations in TTR gene account for over 99% of disease alleles.

1. Confirmation of diagnosis:
   1. In individuals with clinical features suggestive of TTR amyloidosis.
2. Prenatal testing (technically feasible but not routinely performed – contact MGL to discuss):
   1. Pregnancies at risk of TTR amyloidosis where one of the parents has a pathogenic mutation in TTR.
3. Presymptomatic testing:
   1. Adults at risk of TTR amyloidosis due to a family history of molecularly confirmed TTR amyloidosis. Predictive testing will only be performed following genetic counselling by a recognized genetic service.

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

NM_000371.3 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.

Angelman syndrome (AS) is characterized by severe developmental delay or mental retardation, severe speech impairment, gait ataxia, microcephaly and seizures. Individuals with AS often have specific behavioural characteristics including frequent laughing, smiling, and general excitability.

AS is caused by the loss of the maternal expression of the UBE3A gene, which is normally silenced (not expressed) from the paternally-inherited allele. The loss of maternal expression can occur due to one of several different known genetic mechanisms: deletion of the maternal 15q11.2-q13 region (~68%); paternal uniparental disomy (~7%) of chromosome 15; mutation of the imprinting centre in the 15q11.2-q13 region (~3%); or a mutation in the maternal UBE3A allele (~11%).

1. Confirmation of diagnosis:
   1. This test should be used as the first line diagnostic test in a child with a suspected clinical diagnosis of AS 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 AS due to a methylation abnormality. NB: The recurrence risk for couples who have a previous child with AS is generally quite low (< 1%) except in rare cases. Genetic counselling is recommended.   

Differential PCR amplification of bisulfite treated DNA at the CpG island of SNRPN to assess the methylation pattern of this region. Note: This assay detects the methylation patterns associated with both PWS and AS.

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.

Achondroplasia is the most common form of inherited disproportionate short stature, with a prevalence of approximately 1/15,000 to 1/40,000 births. It is characterized by arms and legs that are disproportionately short compared to the trunk. Also characteristic are a large head, frontal bossing, and midface hypoplasia.

Achondroplasia is caused by mutations in the FGFR3 gene, which encodes fibroblast growth factor receptor 3, a negative regulator of bone growth. Inheritance is autosomal dominant, though more than 80% of cases are the result of de novo mutations (i.e., both parents are of normal stature). The missense substitution c.1138G>A (p.Gly380Arg) accounts for more than 98% of mutant FGFR3 alleles in achondroplasia, with c.1138G>C (p.Gly380Arg) accounting for another 1%.

1. Confirmation of diagnosis:
   1. In individuals with clinical features suggestive of achondroplasia.
2. Prenatal testing (prenatal diagnosis requests are not normally accepted from physicians other than Medical Geneticists):
   1. In pregnancies born to a couple in which one or both parents has achondroplasia
   2. In pregnancies where ultrasound findings are suggestive of achondroplasia

Bidirectional Sanger sequencing of the FGFR3 coding region containing codon 380 is carried out to identify the 2 most common mutations in achondroplasia, which account for over 99% of cases.

NM_000142.4 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

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., mutations outside the regions tested as described above, 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. 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 rare 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.

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy; Familial Vascular Leukoencephalopathy; Hereditary Multi-Infarct Dementia

CADASIL is characterized by migraine headaches, adult-onset cerebrovascular disease progressing to dementia, and neuroimaging findings of diffuse white matter lesions and subcortical infarcts.

CADASIL is an autosomal dominant disorder caused by mutations in NOTCH3. All confirmed mutations result in loss or gain of a cysteine residue in one of the EFF-like domains of the protein.

1. Confirmation of diagnosis:
   1. In individuals with clinical features suggestive of CADASIL.
2. Prenatal testing (technically feasible but not routinely performed – contact MGL to discuss):
   1. In pregnancies where one member of the couple has CADASIL and a known NOTCH3 mutation.
3. Presymptomatic testing
   1. In adults known to be at risk due to a family history of CADASIL and the mutation is known. Predictive testing will only be performed following genetic counselling by a recognized genetic service.

Select regions, (exons 2 – 6 and 11 and the flanking intronic sequences of these exons) of the NOTCH3 gene are sequenced using Sanger sequencing. Coverage is bidirectional, with the exception of exon 2, which is unidirectional.

NM_000435.2 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.

Kennedy Disease; X-linked Bulbospinal Neuropathy

Spinobulbar muscular atrophy (SBMA) is characterized by adolescent-onset mild androgen insensitivity (e.g., gynecomastia, small testes, oligo- or azoospermia) in males. This is followed by post-adolescent onset (age 20 – 50) proximal muscle weakness, fasciculations, and atrophy due to lower motor neuron degeneration. Eventually, most individuals with SBMA will have bulbar involvement. Life expectancy is not reduced. Carrier females are unaffected.

SBMA is caused by expansion of a CAG trinucleotide repeat in exon 1 of the androgen receptor (AR) gene on the X-chromosome. Inheritance is X-linked recessive. In general, repeat size roughly corresponds to the severity of disease and age of onset. Alleles in the AR gene are classified as:

• Normal: ≤ 34 repeats
• Questionable Significance: 35 repeats
  There is no consensus regarding the significance of an allele with 35 repeats
• Reduced Penetrance: 36 – 37 repeats
  It has been suggested that alleles with 36 or 37 repeats are reduced penetrance alleles, although this remains unclear.
• Full Penetrance: ≥ 38 repeats

1. Confirmation of diagnosis:
   1. In males with clinical features suggestive of SBMA.
2. Carrier Testing:
   1. Adult females at risk to be carriers of SBMA due to a family history. NB: Daughters of affected male individuals are obligate carriers of SBMA.
3. Prenatal testing (technically feasible, but not routinely performed – contact MGL to discuss):
   1. Male pregnancies at risk of SBMA. Prior to testing for SMBA, fetal sexing is performed; if the fetus is female, further testing is not indicated.
4. Presymptomatic testing:
   1. Adult males at risk of developing SBMA due to a family history. Predictive testing will only be performed following genetic counselling by a recognized genetic service.

The CAG repeat size is determined using 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.

Hypochondroplasia is a skeletal dysplasia characterized by short stature; stocky build; disproportionately short arms and legs; broad, short hands and feet; mild joint laxity; and macrocephaly. The skeletal features are very similar to achondroplasia but tend to be milder. Medical complications common to achondroplasia (e.g., spinal stenosis, tibial bowing, obstructive apnea) occur less frequently in hypochondroplasia, but deficits in mental capacity and/or function may be more prevalent. Children usually present as toddlers or school-age children with short stature; limb disproportion and other features become more prominent with time. Individuals with mild achondroplasia and severe hypochondroplasia present similarly.

The majority of cases of hypochondroplasia are due to mutations in the FGFR3 gene. Inheritance is autosomal dominant, although most cases are due to de novo mutations (i.e., both parents are of normal stature). Approximately 70% of probands with hypochondroplasia are heterozygous for the FGFR3 p.Asn540Lys mutation, due to one of two recurrent FGFR3 mutations, c. 1620C>A (in 70%) and c.1620C>G (in 30%). The achondroplasia mutation, p.Glu380Arg (c.1138G>A; c.1138G>C), may present clinically as severe hypochondroplasia . Other rare FGFR3 mutations have been reported.

1. Confirmation of diagnosis:
   1. In individuals with clinical features suggestive of hypochondroplasia.
2. Prenatal testing (technically feasible, but not routinely performed – contact MGL to discuss):
   1. In pregnancies born to a couple in which one or both parents has hypochondroplasia

Bidirectional Sanger sequencing of the regions of FGFR3 encompassing the common hypochondroplasia mutation p.Asn540Lys (c.1620C>A; c.1620C>G), the rare p.Asn540Thr (c.1619A>C), p.Asn540Ser (c.1619A>G), and p.Ile538Val (c.1612A>G) mutations and the achondroplasia mutation p.Glu380Arg (c.1138G>A; c.1138G>C).

NM_000142.4 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).  

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.

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.

Androgen Resistence Syndrome; AIS.

Androgen insensitivity syndrome spectrum disorder is characterized by feminization of the external genitalia, abnormal secondary sexual development, and infertility in individuals with a 46,XY karyotype.  AIS can be divided into three categories based on the clinical presentation:

• Complete androgen insensitivity syndrome (CAIS), with typical female external genitalia
• Partial androgen insensitivity syndrome (PAIS) with predominantly female, predominantly male, or ambiguous external genitalia
• Mild androgen insensitivity syndrome (MAIS) with typical male external genitalia

AIS is an X-linked disorder caused by mutations in the Androgen Receptor (AR) gene. Individuals with AIS have normal levels of testosterone and dihydrotestosterone production but are unable to utilize it due to the defect in the androgen receptor. These individuals do not respond to testosterone treatment, in contrast to individuals with 5- α reductase deficiency.  The majority of mutations identified to date have been sequence mutations, although a few whole and partial gene deletions have also been identified.

1)      Confirmation of diagnosis:

• Patients with clinical findings consistent with AIS.
• Test requested by an Endocrinologist or Medical Geneticist

2)      Carrier testing:

• Adult women at risk to be carriers of an AR mutation because they have had a child with, or have a family history of confirmed AIS.

3)      Prenatal testing (prenatal diagnosis requests are not normally accepted from physicians other than Medical Geneticists):

• Pregnancies known to be at risk of AIS when the AR mutation is known.

Bidirectional Sanger sequencing of the coding sequence and flanking intronic sequences of the AR gene.

NM_000044 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.

Isolated Craniosynostosis; Non-Syndromic Craniosynostosis; Coronal Craniosynostosis

The phenotype of Muenke syndrome varies considerably. Clinical features may include cranial suture synostosis, ocular hypertelorism, ptosis or proptosis, midface hypoplasia, temporal bossing, high-arched palate, strabismus, hearing loss, developmental delay, intellectual disability; carpal bone and/or tarsal bone fusions brachydactyly, broad toes, broad thumbs, and clinodactyly.

Muenke syndrome is inherited in an autosomal dominant manner, but shows reduced penetrance. All individuals are heterozygous for the FGFR3 mutation c.749C>G (p.Pro250Arg).

1. Confirmation of diagnosis:
   1. In individuals with clinical features suggestive of Muenke syndrome (non-syndromic craniosynostosis).
2. Carrier testing:
   1. Although this is an autosomal dominant condition, carrier testing may be relevant to identify non-penetrant mutation carriers.
3. Prenatal testing (technically feasible but not routinely performed – contact MGL to discuss):
   1. In pregnancies of a couple in which one parent has Muenke syndrome.

Bidirectional Sanger sequencing across the c.749C>G (p.Pro250Arg) FGFR3 mutation.

NM_000142.4 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).  

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.

Hereditary Motor and Sensory Neuropathy 1A

Charcot-Marie-Tooth disease is a chronic motor and/or sensory neuropathy typically characterized by distal muscle weakness, sensory loss, and pes cavus deformity. Charcot-Marie-Tooth Type 1A (CMT1A) accounts for ~75% of Charcot-Marie-Tooth type 1 (CMT1), and CMT1 accounts for nearly half of all Charcot-Marie-Tooth disease.

CMT1A is caused by an 1.5 Mb duplication in 17p11.2, which results in the inheritance of three copies of the PMP22 gene. Inheritance is autosomal dominant; 20 – 33% of cases are due to de novo duplications. Rare cases of homozygous duplications (resulting in a total of four copies of PMP22) have been described and, in general, manifest a more severe phenotype than the typical three-copy cases.

1. Confirmation of diagnosis:
   1. In individuals with clinical features suggestive of CMT1.
2. Prenatal testing (technically feasible but not routinely performed – contact MGL to discuss):
   1. Pregnancies to couples in which one person has confirmed CMT1A .
3. Presymptomatic testing
   1. Adults at risk of inheriting CMT1A from a parent may be referred for presymptomatic testing for CMT1A.
   2. Requests to test asymptomatic children who are at risk of developing CMT1A are only accepted following genetic counselling by a recognized genetic service.

Multiplex ligation-dependent probe amplification (MLPA) analysis is carried out with the P033-B2 probe mix (MRC-Holland) to determine the gene dosage (i.e. number of copies) of the PMP22 gene. Note: This assay will detect both CMT1A and HNPP.

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). 

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.