Tyrosinemia I



Test Description:

Tyrosinemia is characterized by high levels of the amino acid tyrosine in the blood, which may be caused by one of several different defects in the tyrosine metabolism pathway. Tyrosinemia type I may present in the neonatal period up until early adulthood, with the most severe forms occurring early in life. Affected individuals present with gastrointestinal problems leading to a failure to thrive, jaundice, and a cabbage-like odor to the body or urine. Kidney failure may lead to bleeding, ascites, and sepsis. Liver disease may occur. In patients who present at an older age, liver disease and painful neurological episodes may occur. Due to cirrhosis of the liver, all patients are at an increased risk of developing hepatocellular carcinoma. Treatment involves a protein-restricted diet and nitisinone (NTBC) therapy, which greatly improves symptoms and outcome. Tyrosinemia type I is due to mutations in the gene FAH, which encode the enzyme fumarylacetoacetate hydrolase. Patients of Ashkenazi Jewish background have been found to carry the mutation p.P261L, with a carrier frequency of 1 in 143. Testing for this mutation, as well as five others (c.554-1G&gtT, c.1062+5G&gtA, p.Q64H, p.W262*, p.E357*) is expected to identify over 95% of mutations in this population.

Full gene sequencing is available for reproductive partners of known mutation carriers. Prenatal diagnosis is also available. Prior to ordering prenatal testing, please contact our laboratory at 212-241-7518 to discuss.

References:

1. Elpeleg ON, Shaag A, Holme E, Zughayar G, Ronen S, Fisher D, Hurvitz H.Mutation analysis of the FAH gene in Israeli patients with tyrosinemia type I. Hum Mutat. 2002 Jan19(1):80-1


Forms and Brochures




Specimen Requirements


Post-natal

Two 5-10 mL tubes of anticoagulated blood in EDTA (lavender top) or two 5-10 mL tubes of anticoagulated blood in ACD (yellow top).

Prenatal

Chorionic Villi: 5-10 mg in conical tube with sterile saline OR transport media
Amniotic Fluid: 10 ml in conical tube
Cultured Cells: Two confluent T-25 flasks

Additionally, please send:

5-10 ml maternal blood in EDTA (lavender top) required to perform MCC studies on all prenatal samples and in case maternal confirmation studies are necessary
5-10 ml paternal blood in EDTA (lavender top) in case paternal confirmation studies are necessary

Ordering Information


Shipping:

Ship at room temperature

Turnaround Time:

10 – 14 days

CPT Codes:

81401


Forms and Brochures


Carrier Screening Requisition and Consent [PDF]
Expanded Ashkenazi Jewish Carrier Screening Brochure [PDF]
Ashkenazi Jewish Carrier Screening Panel