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HelpTest Code LAB1849 Galactosemia DNA Analysis
Clinical System Name
Galactosemia (GALT) DNA Analysis
Synonyms
Galactosemia DNA (8 mutations)
Galactosemia Common Mutation Panel
Description
Galactosemia affects about 1/10,000 individuals and is included in the Washington State newborn screening program.
This targeted test is for the analysis of 8 common variants in the GALT gene: p.Ser135Leu (c.404C>T), p.Phe171Ser (c.512T>C), p.Gln188Arg (c.563A>G), p.Leu195Phe (c.584T>C), p.Tyr209Cys (c.625A>G), p.Lys285Asn (c.855G>T), p.Asn314Asp (c.940A>G) (Duarte variant), p.Leu218Leu (c.1721C>T) (LA variant)
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
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 |
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 |
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
| GALT 8 Mutation Panel | 81401 |
| GALT Targeted Variant Analysis | 81403 |
Methodology
Method: PCR + Sequencing
Limitations: This test is for the specified targeted 8 variants analysis only.
Reference Range
Interpretive report will be provided
Requisition
Special Instructions
Links to: Galactosemia GeneReview
Clinical Utility
Galactosemia is an inherited disorder of galactose metabolism. Individuals with galactosemia are unable to break down galactose, a sugar found primarily in dairy products and some vegetables and legumes. Galactosemia is caused by a deficiency in the enzyme galactose-1-phosphate uridyltransferase, and individuals with galactosemia have mutations in the GALT gene. They also have elevated galactose-1-phosphate, a metabolite of galactose metabolism. Galactosemia affects about 1/10,000 individuals and is included in the Washington State newborn screening program.