Test Code LAB1926 Wilson Disease Sequencing
Clinical System Name
Wilson Disease (ATP7B) Sequencing
Description
Wilson disease is an autosomal recessive disorder of copper metabolism. Sequencing of the ATP7B gene can identify greater than 98% of mutations in affected individuals.
ATP7B gene sequencing is appropriate for individuals with:
- Liver disease
- Neurologic presentations
- Psychiatric disturbance
- Low serum copper & ceruloplasmin levels
- Increased urine copper
- Kayser-Fleisher rings in the cornea
- Increased hepatic copper levels
Also available: Targeted Gene Variant Sequencing (LAB1915) - For targeted analysis of variants previously identified through clinical testing of a family member or research testing of the individual. Please review requirements and restrictions for testing.
Sample Requirements
Note: For patients who have had a whole blood transfusion, wait 10 days post transfusion to draw for genetic testing. No wait time is necessary for blood or saliva collection if the patient received leuko-reduced red cells or plasma.
Specimen: Whole blood
Container(s): Lavender/EDTA
Preferred Vol: 3 mL
Minimum Vol: 1 mL
Note: Heparin samples (Green tops) are unacceptable.
Specimen: Extracted DNA (MUST specify source on requisition)
Preferred: 5µg
Minimum: 2µg
Note: Isolation of nucleic acids for clinical testing must be performed in a CLIA-certified
laboratory or a laboratory meeting equivalent requirements as determined by the CAP
and/or the CMS. DNA concentration minimum 50 µg/mL; 260/280 ratio 1.70-2.00.
Specimen: Saliva collected using Oragene Dx OGD-575/675 collection kit.
Container: Oragene Dx OGD-575/675 collection kit
IMPORTANT NOTE: Manufacturer instructions must be followed. The Oragene Dx OGD575/675 kit is not for children under 6 months. Contact Lab Client Services for more information or to obtain a kit 206-987-2617, labclientservices@seattlechildrens.org
Processing Instructions
Specimen Type | Description |
Temperature |
Storage instructions |
Whole blood | EDTA or ACD tube | Refrigerate | Molecular Genetics box in CPA refrigerator #2 |
Extracted DNA | DNA aliquot tube | Refrigerate | Molecular Genetics box in CPA refrigerator #2 |
Saliva | OGD-575/675 kit | Room temp | Place in CPA Cytogenetics room temp box |
Off-site collection: Refrigerate blood samples until ready to ship. Transport blood or DNA at room temperature via overnight shipping.
Stability
Specimen Type | Temperature | Time |
---|---|---|
Whole blood | Room temp | 3-5 days |
Whole blood | Refrigerated | 7 days |
Extracted DNA | RT, refrig or frozen | stable |
Saliva, ORAgene Dx OGD-575/675 | Refrig or room temp | up to 2 weeks |
Note: Whole blood samples > 7days may be submitted to be assessed by our lab for acceptability for testing.
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Molecular Genetics Laboratory
Phone: 206-987-3872
Lab Client Services: 206-987-2617, labclientservices@seattlechildrens.org
Lab Genetic Counselor: LabGC@seattlechildrens.org
Lab Client Services: 206-987-2617
Lab Genetic Counselor: LabGC@seattlechildrens.org
Availability
STAT | Performed | TAT |
---|---|---|
Contact lab | Monday - Friday | 4-6 weeks |
Methodology
Method: Next Generation Sequencing technology using an Illumina NextSeq instrument. Target region includes coding exons and a minimum of 10 bp of flanking intron boundaries of the genes tested. Target enrichment performed using a custom Integrated DNA Technologies (IDT) Exome Hyb Panel v2.
Average coverage ~150x, depth of coverage for all target regions is at least 20x.
Limitations:
This testing is performed on an exome backbone with analysis restricted to the target gene. This method can detect single nucleotide variants (SNVs), small deletions, small insertions, and copy number variants in the regions targeted. Some regions cannot be efficiently captured due to sequence homology or sequence properties. This method will not detect large insertions and deletions, complex indels, structural variants (e.g. inversions, translocations), short tandem repeats, or other complex variants. Variants located outside of targeted regions will not be detected.
Based on validation studies, the bioinformatics pipeline showed precision and detection >99% for SNVs in regions with coverage greater than 20x and high mapping quality. Sensitivity for CNVs involving multiple genes is >99% and sensitivity for intragenic CNVs is >90%. Mosaic sequence variants present at <25% allele frequency may not be reliably detected, and detection sensitivity is dependent on the nature of the variant. The sensitivity of detection of mosaic copy number variants has not been evaluated.
Reference Range
Interpretive report will be provided. Variants are not reported if they are considered benign.
CPT Codes
81406
Requisition
Special Instructions
Links to: Wilson Disease GeneReviews
Clinical Utility
Wilson disease is an autosomal recessive disorder of copper metabolism. Copper accumulation in tissues and organs can lead to liver disease, neurological symptoms including movement disorders, dysarthria, dystonia, migraines and seizures; and psychiatric symptoms including depression, personality changes and psychoses. Many individuals will have characteristic changes to their cornea called Kayser-Fleischer rings.
The age of onset can be from childhood to adulthood; signs and symptoms are rarely observed in children under 3 years of age. Children tend to present with liver disease as their primary symptom, whereas most neurological and psychiatric symptoms tend to arise in adulthood.
Full gene sequencing will identify greater than 98% of mutations in affected individuals.
Carrier testing for biological family members is available once mutations are known.