Fragile X (FMR1) with Reflex to Methylation Analysis, Fetal
Use
This test is designed for the prenatal diagnosis of fragile X syndrome in fetuses of mothers who carry fragile X premutations or full mutations. Fragile X syndrome (FXS) is characterized by intellectual disability, behavioral and learning challenges, and various physical characteristics. The syndrome is caused by CGG triplet repeat expansion in the FMR1 gene on the X chromosome. This test uses PCR and capillary electrophoresis to detect the number of CGG repeats and reflexes to methylation analysis if necessary, to distinguish between full mutation and premutation alleles.
Special Instructions
The test requires a Fetal Molecular Testing Patient History Form and informed consent for genetic testing, especially required for patients in New York. If the CGG repeat number is 100 or greater, methylation analysis will be automatically added, which incurs additional charges.
Limitations
The test may not accurately distinguish between premutation and full mutation alleles in early gestation due to the incomplete establishment of methylation patterns. It has specific limitations around the detection of AGG trinucleotide interruptions within the CGG repeat tract and is not recommended for diagnostic testing on chorionic villus samples. Diagnostic errors might occur due to rare sequence variations and other factors not related to repeat size.
New York Approved
Methodology
PCR-based (PCR)
Biomarkers
LOINC Codes
- 59266-7
- 45321-7
- 45322-5
- 41107-4
- 66746-9
- 36914-0
Result Turnaround Time
9-10 days
Related Documents
For more information, please review the documents below
Specimen
Cultured Cells
Volume
Not provided
Minimum Volume
Not provided
Container
Two T-25 flasks at 80 percent confluence (Min: one T-25 flask at 80 percent confluence)
Collection Instructions
Backup cultures must be retained at the client's institution until testing is complete. If ARUP receives a sample below the minimum confluence, Cytogenetics Grow and Send (ARUP test code 0040182) will be added on by ARUP, and additional charges will apply.
Storage Instructions
CRITICAL ROOM TEMPERATURE. Must be received within 48 hours of collection due to viability of cells.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 48 hours |
| Refrigerated | Unacceptable |
| Frozen | Unacceptable |
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