Order Code: 332122
CPT Codes: 81243, 81244*, G0452
*81244 (Southern blot) will be billed only when:
PCR identifies an allele size ≥55 CGG repeats
Indication: Carrier Screening; Clinical Diagnosis or Prenatal testing
Required Patient Information: Personal and Family History of clinical symptoms and/or previous test results (if any); For prenatal testing: LMP date or gestational age at the time of sample collection
Turn Around Time for PCR: 7-14 days
Turn Around Time for Southern Blot: 21 days
Specimen type: Whole Blood, Amniotic Fluid, Chorionic Villi*
*Chorionic villi will be accepted for PCR only; it is not a reliable sample for Southern blot analysis
Methodology: A single tube CGG repeat primed PCR based assay using two gene-specific primers that flank the triplet repeat along with a third primer that is complementary to the (CGG)n repeat is used to determine genotypes for CGG allele sizes within the Fragile X gene (FMR1). This assay will identify alleles of all sizes but cannot determine methylation status of expanded alleles. Reflex to a Southern blot assay will be performed for all samples with an allele size ≥55 CGG repeats, to determine methylation status.
Other Requirements: A maternal blood sample is required for all prenatal specimens.