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Tyrosinemia Type I Mutation Analysis

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.

Test Name: Tyrosinemia Type I (6 mutations)
Test Code:
TYR DNA
Test Description:
Analysis of the FAH gene for the following mutations:
IVS12+5g>a
IVS6-1g>t
p.P261L
IVS7-6t>g
p.E357X.
p.G337S
This panel of mutations will detect 75% of the mutations associated with tyrosinemia type 1 in the US Caucasian population.
Synonyms:
tyrosinemia; amino acid disorders; hepatorenal tyrosinemia
Indication:
This test is used to provide additional information regarding diagnosed patients, provide carrier testing for at-risk family members or general population carrier screening. Prenatal testing can be performed if both mutations are known.
Related Tests: Organic Acid Analysis, Urine  
This test is for confirmation of newborn screening results, evaluating patients with episodes of lethary or vomiting suggestive of a metabolic disorder and for follow-up of known patients for assessment of management.

Amino Acids, Quantitative  
This test is for confirmation of newborn screening results, evaluating patients with episodes of lethary or vomiting suggestive of a metabolic disorder and for follow-up of known patients for assessment of management.

NTBC (Orfadin) Level  
Quantitative assay of blood nitisinone levels. It is for monitoring therapeutic drug levels in patients being treated with Orfadin.

Succinylacetone Screening, Urine  
This is a semi-quantitative assay for succinylacetone as part of urine organic acids. This screen is used for patients suspected of having tyrosinemia type I.

Succinylacetone Quantitation, Urine  
This stable isotope assay is used for monitoring known patients with tyrosinemia type I

Maternal Cell Contamination - DNA  
Maternal DNA is compared to fetal DNA to evaluate whether maternal cell contamination of the fetal sample has occurred.

Clinical Links: Tyrosinemia Type I Gene Review
University of Washington Tyrosinemia Webpage
Availability:
Set up daily
Turnaround Time:
2 weeks
Methodology:
PCR and sequencing
Reference Range:
Interpretive report provided
Requisition:
Consent Form:
Sample Requirements: Type
Whole blood: 1-3 ml lavender(EDTA) or yellow (ACD A or B) tube.
DNA: 5-10ug extracted DNA
Prenatal samples: 2 T-25 flasks cultured CVS or amniocytes.

Processing
Keep at room temperature.

Shipping
Ship overnight at room temperature. Sample should be received within 3 days of draw.
Samples Received:
Mon - Fri 8:00am - 5:00 pm PST
Special Considerations:
For prenatal testing, maternal cell contamination testing is required (ordered separately).
Cost:
Please e-mail Lab Client Services (labclientservices@seattlechildrens.org) or call at 206-987-2617 with any billing questions
CPT Code:
Please e-mail Lab Client Services (labclientservices@seattlechildrens.org) or call at 206-987-2617 with any billing questions