LESCH-NYHAN SYNDROME
HPRT1 Sequencing
DNA ANALYSIS
Also see: Hypoxanthine Phosphoribosyl Transferase (HPRT) - Biochemical Analysis; 4220 - Urinary Purine Profile

Lesch-Nyhan syndrome (LNS) is an X-linked recessive inborn error of metabolism caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT). LNS is characterized by motor dysfunction, cognitive and behavioral disturbances, and uric acid overproduction (hyperuricemia). Patients have both extra-pyramidal signs (dystonia, choreoathetosis) and may also have pyramidal features including hyperreflexia and clonus. There is cognitive impairment and self-injurious behavior. Overproduction of uric acid may lead to deposition of uric acid crystals or calculi in the kidneys, ureters, or bladder. Definitive diagnosis is obtained by measurement of HPRT enzyme activity in blood or tissue. Sequence analysis of the entire HPRT1 gene associated with LNS is available on a clinical basis at the Medical Genetics Laboratories at Baylor College of Medicine.

Reasons for Referral:

Confirmation of clinical diagnosis of Lesch-Nyhan Syndrome.
Analysis of at-risk family members for identified mutations. Population carrier screening not offered.
Prenatal diagnosis (Known familial mutation only).

Testing Methodology:

Full Sequencing: A PCR-based assay is used to amplify all 9 exons of the HPRT gene. Direct sequencing of amplification products is performed in both the forward and reverse directions using automated fluorescence dideoxy sequencing methods.

Sensitivity:

Clinical: Approximately 80%
Analytical: > 98%

Specimen Requirements:

Blood for DNA: EDTA (purple-top) tubes: Adult/Child: Minimum 6-14 cc
Requisition form must accompany the specimen. Prior to any genetic testing, we recommend genetic counseling and we request that the subject sign our consent statement and submit it with the sample. To receive forms, additional information or specimen collection kits, please contact the laboratory. Please call laboratory for specific requirements for prenatal testing.

Turnaround Time:

Index: 4 weeks
Known Familial Mutation: 3 weeks

CPT Codes and Prices:

Index: 83891x1, 83898x11, 83894x1, 83904x22, 83909x22, 83912x1
Known Familial Mutation: 83904x2, 83912, 83909x2, 83898, 83891, 83894

References:

1. Patel PI, et al. (1986) Fine structure of the human hypoxanthine phosphoribosyltransferase gene. Molec. Cell. Biol. 6: 393-403.

Shipping Information

Forms:

>> Gene Sequencing Requisition
>> Prenatal Requisition

Test Codes:

Index: 6240
Known Familial Mutation: 6245
Prenatal (Known Familial Mutation Only): 6250