Home
HelpTest Code LAB3530 Tyrosinemia Type I, Mutation Analysis
Clinical System Name
Tyrosinemia (FAH) DNA Analysis
Description
Tyrosinemia type I is an autosomal recessive disorder caused by a deficiency of the enzyme fumarylacetoacetate hydrolase.
Analysis of the FAH gene for the following 6 common variants: IVS12+5g>a, IVS6-1g>t, p.P261L, IVS7-6t>g, p.E357X., p.G337S.
This test may be indicated for individuals with:
- Elevated blood tyrosine and methionine
- Elevated blood alpha-fetoprotein
- Succinylacetone in 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
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 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
81479
Methodology
Method: PCR + Sequencing
Limitations: This test is for targeted 6 mutation analysis only.
Reference Range
Interpretive report will be provided
Requisition
Special Instructions
Links to: Tyrosinemia Type I GeneReviews. University of Washington Tyrosinemia Webpage
Clinical Utility
Tyrosinemia type I is an autosomal recessive disorder caused by a deficiency of the enzyme fumarylacetoacetate hydrolase. The disease manifests primarily as liver disease, with hepatic cirrhosis and accompanying renal tubule damage as a result of the build up of succinylacetone. Biochemically, the hallmarks of the disease are elevated blood tyrosine and methionine, elevated blood alpha-fetoprotein, and succinylacetone in the urine. The diagnosis is confirmed by the presence of succinylacetone in urine.
The disease is common in the French Canadian population, with a carrier frequency of 1/25 in people from the Saguenay-Lac St. John region of Quebec. The overall carrier frequency in Quebec is 1/66.