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The Kleberg Cytogenetics Laboratory offers a fluorescence in situ hybridization (FISH)-based assay for identifying the microdeletion on chromosome 8q24.1 associated with trichorhinophalangeal syndrome, type I (TRPSI). Clinical Features:Trichorhinophalangeal syndrome (TRPSI) is characterized by craniofacial anomalies, sparse hair, and cone-shaped epiphyses. The phenotype is variable and may overlap with the phenotype of Langer-Giedion syndrome (LGS), however, trichorhinophalangeal syndrome is limited to the facial features and cone-shaped epiphyses seen in LGS. Most TRPSI patients do not have mental retardation or exostoses. Reasons for Referral:FISH can be used to detect deletions in patients with a suspected diagnosis of TRPSI. 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 TRPSI is performed on metaphase chromosomes. The absence of a hybridization signal indicates a deletion. Only a small percentage (<30%) of individuals with TRPSI will have microdeletions of 8q that can be detected by FISH. The majority of patients with TRPSI (70%) have point mutations in the TRPSI gene. Due to the clinical variability of both LGS and TRPSI, patients deleted for the TRPSI locus will be offered additional testing to detect the deletion of EXT1 associated with Langer-Giedion syndrome. Specimen Requirements:Whole blood in sodium heparin (green-top) tubes: Shipping and Handling:All tubes must be labeled with the patient's testname 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 References:1. Momeni P, et al. (2000) Nat. Genet. 24: 71-74. Forms: >> Cytogenetics
Requisition Test Code:8482 |