The Kleberg Cytogenetics Laboratory offers a fluorescence in situ hybridization (FISH)-based assay for identifying the deletion in the short arm of the X chromosome at band Xp21 associated with adrenal hypoplasia congenita (AHC). Clinical Features:Acute infantile onset of adrenal hypoplasia congenita is characterized by adrenocortical insufficiency, feeding difficulties and hypogonadotropism. Affected males may also present in childhood or adulthood. Carrier females may have adrenal insufficiency or hypogonadotropic hypogonadism. Reasons for Referral:Patients suspected of having adrenal hypoplasia congenita can be tested for deletions using a probe specific for the DAX-1 (NROB1) gene. FISH may also identify carrier females. Prenatal diagnosis may be performed if an affected family member has been studied in our laboratory and shown to have a deletion detectable by FISH. Please call regarding all prenatal samples. Testing Methodology:FISH is the application of fluorescently labeled DNA molecules to metaphase chromosomes and interphase nuclei for the detection of chromosome abnormalities and alterations. It is a rapid, reliable and direct approach for identifying patients with microdeletions or microduplications. FISH analysis for AHC is performed on metaphase chromosomes. The absence of a hybridization signal indicates a deletion. Some individuals have been shown to have large deletions of Xp21 and manifest several clinical features that may include adrenal hypoplasia congenita, glycerol kinase deficiency (GK) and Duchenne Muscular Dystrophy (DMD). These patients have a contiguous gene deletion syndrome that can be identified by the combined use of the adrenal hypoplasia congenita FISH probe, the glycerol kinase gene FISH probe and DMD-specific FISH probes. Males with isolated AHC may have a mutation in the NROB1 gene detectable by sequencing, therefore, a negative FISH study does not rule out AHC. Specimen Requirements:Whole blood in sodium heparin (green-top) tubes: Shipping and Handling:All tubes must be labeled with the patient's name and date of birth, and a completed requisition form must accompany each sample. If the laboratory is billing the patient's insurance, please enclose a copy of the insurance card. Ship specimens for overnight delivery at ambient temperature. Please notify the laboratory of incoming samples. Turnaround Time:7-10 days CPT Codes and Prices:88230, 88271, 88273, 88291 Forms:>> Cytogenetics Requisition References:
Test Codes:8457 |