Fragile X Syndrome: FMR1 Methylation Analysis

Additional characterizations of FMR1 expansions for methylation status following abnormal PCR detection of abnormal allele.

Turnaround Time

21 days

CPT Code(s)

81244

Cost

$530

Genes

• Fragile X syndrome

Fragile X syndrome is the most common form of inherited intellectual disability. Approximately 1/1250 males and 1/2500 females are affected by the condition. Some population studies have shown the carrier frequency to be as high as 1/250 individuals. The American College of Medical Genetics policy statement on Fragile X testing recommends consideration of testing for males or females with intellectual disability, developmental delay or autism, those with a family history of Fragile X syndrome or unexplained intellectual disability. Additionally, prenatal testing should be offered to known carrier females. Trinucleotide repeat analysis is the standard for Fragile X diagnosis. Patients with the above characteristics who had a previously normal cytogenetic Fragile X result should also be considered for trinucleotide repeat analysis. Methylation status may modify the phenotype observed.

Follow-up analysis for patients with abnormal Fragile X testing that did not include methylation.

Methylation Analysis

Methylation-sensitive PCR is able to confirm the presence of an expansion and determine methylation status.

The preferred sample type is 3-5 ml of peripheral blood collected in an EDTA (purple top) tube. Extracted DNA and saliva are also accepted for this test. Saliva samples must be submitted in an approved saliva kit. Contact the lab to receive a saliva kit or to have one sent to your patient.

The specimen should be kept at room temperature and delivered via overnight shipping. If shipment is delayed by one or two days, the specimen should be refrigerated and shipped at room temperature. Do not freeze the specimen. Samples collected on Friday can be safely designated for Monday delivery.

Prenatal diagnosis is available if the familial mutations are known. Additional fees for cell culture and maternal cell contamination may apply. Maternal cell contamination studies are required for all prenatal molecular tests. Contact the laboratory prior to sending a prenatal specimen.