FMR1 CGG Repeat Analysis
Use
The FMR1 CGG Repeat Analysis is designed to identify expansions of a CGG trinucleotide repeat in the 5’ untranslated region of the FMR1 gene, enabling differentiation of fragile X syndrome from other causes of intellectual disability and autism spectrum disorders. It is also used for preconception or prenatal carrier testing in women with personal or family history of fragile X syndrome, unexplained intellectual disability, autism spectrum disorders, or primary ovarian insufficiency, and for carrier testing in at‑risk relatives.
Special Instructions
Preferred specimen is 2–5 mL of whole blood collected in a lavender‑top (EDTA) tube; an alternative specimen is buccal swabs. No ABN is required. The test requires submission using the neurology test requisition and includes the test information sheet. Repeat testing for at‑risk family members may use the same test code.
Limitations
This assay uses PCR fragment analysis to detect CGG repeat expansions; extremely large expansions or mosaicism might be difficult to characterize, and this method may be less sensitive for very high‑level mosaicism or methylation status. Exome or genome sequencing is recommended by ACMG as a first‑tier test for developmental delay or congenital anomalies and may detect additional diagnoses beyond FMR1 expansions.
New York Approved
Methodology
PCR-based (PCR)
Biomarkers
Result Turnaround Time
14 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
2–5 mL
Minimum Volume
Not provided
Container
Lavender‑Top Tube (EDTA)
Other tests from different labs that may be relevant