Test Overview
Fragile X fragment analysis, performed using the Asuragen AmplideX PCR/CE FMR1 Reagents, uses GC-rich optimized polymerase chain reaction (PCR) and capillary electrophoresis to determine the number of cytosine-guanine-guanine (CGG) repeats in the Fragile X Messenger Ribonucleoprotein 1 (FMR1) gene 5’ untranslated region. A PCR primer pair amplifies the entire CGG repeat region, and a separate primer randomly anneals inside and amplifies different portions of the CGG repeat region resulting in small fragments of three nucleotides difference (CGG primed “shoulder” peaks). FMR1 methylation analysis, performed using the Asuragen AmplideX mPCR FMR1 Kit, uses methylation-sensitive enzyme digestion followed by PCR and capillary electrophoresis to determine the methylation status of the FMR1 5’ untranslated region. Methylation analysis is only performed for a patient with a premutation or a full mutation CGG repeat expansion.
Analysis of CGG repeats present in the FMR1 gene in a patient with clinical features consistent with Fragile X Syndrome or determination of the carrier status of a family member.
*Reference ranges may change over time. Please refer to the original patient report when evaluating results.
Normal alleles: 5-44 CGG repeats; Intermediate (gray zone) mutations: 45-54 CGG repeats; Premutations: 55-200 CGG repeats; Full Mutation: >200 CGG repeats. Interpretative report provided.
* Reference ranges may change over time. Please refer to the original patient report when evaluating results.
This assay can detect up to 200 CGG repeats in the FMR1 gene. Samples containing > 200 CGG repeats will be reported as "full mutation (>200 CGG repeats)".
Test Details
Specimen Requirements
Cheek swab kit (Oragene OCD-100), follow collection instructions.
Saliva kit (Oragene OGD-510), follow collection instructions.
This test is not orderable for MLABS clients.
1 Saliva Kit
1 Saliva Kit
Additional Information
The American College of Medical Genetics recommends that both a routine karotype (Chromosome Analysis, Blood, Constitutional) AND a molecular test (Fragile X Syndrome Mutation Detection) be performed. Most insurance carriers require prior authorization for genetic testing. Testing will not begin until insurance prior authorization is received by the laboratory or it is confirmed that prior authorization is not required. The ordering health care provider can obtain the prior authorization or request the laboratory to submit it. To obtain BCN prior authorization call Joint Venture Hospital Laboratories (JVHL) at 800-445-4979; for all other insurances, contact the plan directly. By ordering this test the clinician acknowledges that informed consent, https://mlabs.umich.edu/sites/default/files/2023-04/file/germline-conse…, has been obtained from the patient as required by applicable state or federal laws and the ordering clinician has authorization from the patient permitting MLabs to report the test results to the ordering clinician. Test includes medical geneticist interpretation of results billed as a separate additional charge. This test is not available without interpretation.