| Achondroplasia Mutation Analysis | 16061X |
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| For New York patient testing, use test code 16062X.This test was developed and its performance characteristics have been determined by Quest Diagnostics Nichols Institute. It has not been cleared or approved by the U.S. Food and Drug Administration. The FDA has determined that such clearance or approval is not necessary. Performance characteristics refer to the analytical performance of the test. | ||
| CPT Code(s): 83891; 83892 (x2); 83900; 83909; 83914; 83912 | Clinical Significance: 1.Prenatal diagnosis of Achondroplasia when one or both of the parents have Achondroplasia. 2.To determine if a fetus has Achondroplasia when an ultra sound shows abnormal bone structure. 3.To confirm, a phenotypically diagnosed case of Achondroplasia. |
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| Specimen Container: EDTA (lavender-top) |
| Preferred Specimen: 5 mL whole blood (3 mL. Minimum) |
| Instructions: Whole Blood: Normal phlebotomy procedure. For prenatal diagnosis, call the laboratory. Amniotic Fluid: Normal collection procedure. Submit 20 mL. Amniocyte or CVS culture: 2 sterile T25 flasks, filled with culture medium.. Dissected chorionic villi (CVS) biopsy: 10-20 mg dissected CVS collected in sterile tube filled with sterile culture medium. Specimen stability is crucial. Store and ship ambient immediately. Do not refrigerate or freeze. |
| Transport Temperaturer: Room temperature, stable 8 days |
| Methodology: Polymerase Chain Reaction, Single Nucleotide Primer Extension |
| Reference Range: Achondroplasia (ACH) is the most common form of rhizomelic dwarfism in humans. Although inherited as an autosomal disorder, over 80% of the cases are caused by de novo (or sporadic) mutations. Over 99% of the individuals with ACH have one of the two mutations in the fibroblast growth factor receptor-3 gene (FGFR3, located at 4p16.3). These two mutations, 1138G>A and 1138G>C, are located in exon 10 of the FGFR3 gene and both cause the substitution of a glycine by arginine at position 380 (G380R). Sporadic mutations are associated with increased paternal age suggesting that the new mutations occur preferentially during spermatogenesis. The two mutations are detected by amplification of the FGFR3 gene region by polymerase chain reaction (PCR), followed by single nucleotide primer extension, and detection of the extension products on an automated fluorescent DNA sequencer. |
| Reject Criteria: Refrigerated or frozen |
