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HelpTest Code LAB1921 VLCAD Sequencing
Clinical System Name
VLCAD (ACADVL) Sequencing
Description
Very Long Chain Acyl-CoA Dehydrogenase Deficiency (VLCAD) is a treatable disorder of fatty acid metabolism caused by an inability to use very-long-chain fats for energy. It is caused by mutations in the ACADVL gene.
ACADVL full gene sequencing is appropriate for:
- Infants with abnormal newborn screening results
- Infants with hypoglycemia, liver disease and cardiomyopathy
- Children with hypoglycemia, enlarged liver, muscle weakness & cramping with reddish-brown urine
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, cord blood
Container(s): Lavender/EDTA, Yellow/ACD A or B
Preferred Vol: 3 mL
Minimum Vol: 1 mL
Note: Heparin samples (Green tops) are unacceptable.
Specimen: Extracted DNA from EDTA blood
Minimum: 10µg
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: Cultured cells
Acceptable: Fibroblasts
Container(s): T-25 flasks
Preferred Vol: 2 flasks
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
Reject due to: Heparin
Spin: No
Aliquot: No
Temp: Refrigerate
Storage location: Molecular Genetics box in CPA refrigerator #2
Off-site collection: Refrigerate blood samples until ready to ship. Transport all sample types at room temperature via overnight shipping.
Stability
| Specimen Type | Temperature | Time |
|---|---|---|
| Cultured cells | Room temp | 3 days |
| Whole blood, extracted DNA | Room temp | 3-5 days |
| Whole blood, extracted DNA | Refrigerated | 7 days |
| Extracted DNA | Frozen | ok |
| Saliva, ORAgene Dx OGD-575/675 | Room Temp | 2 weeks |
Note: Whole blood samples > 7days may be submitted to be assessed by our lab for acceptability for testing.
Availability
| STAT | Performed | TAT |
|---|---|---|
| Contact lab | Monday - Friday | 2-3 weeks |
Follow-up testing requested based on Washington State Lab Newborn Screening Program referrals will be expedited.
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Molecular Genetics Laboratory
Phone: 206-987-3872
Lab Client Services: 206-987-2617
Lab Genetic Counselor: LabGC@seattlechildrens.org
CPT Codes
81406 (updated 2/2/16 by jconta)
Methodology
Method: Bi-directional sequencing of the entire coding region (20 exons) of the ACADVL gene.
Limitations: Mutations in the promoter region, large deletions, large duplications, or rare recombinant mutations may not be detected by this method.
Reference Range
Interpretive report will be provided
Requisition
Special Instructions
Links to: VLCAD Genetics Home Reference Entry , Very Long-Chain Acyl-Coenzyme A Dehydrogenase Deficiency GeneReviews
Clinical Utility
VLCAD is a treatable disorder of fatty acid metabolism caused by an inability to use very-long-chain fats for energy. Fatty acid metabolism occurs during prolonged fasting and/or periods of increased energy demands (fever, stress) when energy production relies increasingly on fat metabolism. Severe VLCAD can cause hypoketotic hypoglycemia, hepatomegaly, cardiomyopathy and arrhythmias, lethargy, and failure to thrive. The age of onset can be from early infancy to adulthood. Infants can present with hypoglycemia, liver disease, and cardiomyopathy. Children who present outside of the newborn period present with hypoglycemia, enlarged liver, and muscle weakness. Most patients who show symptoms in teen years or adulthood have periods of muscle weakness and cramping with reddish-brown urine. 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.