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Test Code TYR DNA 1 Tyrosinemia Type I, Known Mutation

Clinical System Name

Tyrosinemia, DNA 1 Mutation

Description

This test involves targeted analysis for mutations previously identified through clinical testing of a family member or  research testing of the individual.  It can be used for carrier testing for at-risk relatives and prenatal testing for confirmed carriers. Mutations must be known. For individuals who do not meet the criteria of known mutations, see Tyrosinemia Mutation Analysis for common mutation panel testing.

 

Tyrosinemia type I is an autosomal recessive disorder caused by mutations in the FAH gene that result in a deficiency of the enzyme fumarylacetoacetate hydrolase.

Sample Requirements

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

Minimum: 10µg

Note: 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 Counselors: LabGC@seattlechildrens.org

Reference Range

Interpretive report will be provided

Methodology

Method: PCR + Sequencing

 

Limitations: This test is for targeted known mutation analysis only.  Mutations must be known.

CPT Codes

81479

Special Instructions

Please provide copies of proband reports when requesting known mutation analysis for cases NOT performed by Seattle Children's Lab.

 

Links to: Tyrosinemia Type I GeneReviewsUniversity of Washington Tyrosinemia Webpage

Requisition

Molecular Genetics

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.