Test catalog
FMR1 expansion test for Fragile X
Analysis of CGG repeats in the FMR1 gene by PCR and capillary electrophoresis, distinguishing normal, intermediate, premutation and full mutation ranges.
- Accepted samples
- Peripheral blood (preferred), Buccal swab, Extracted DNA
- Turnaround time and when it starts
- 15 calendar days, after order confirmation
- Medical order
- Required. View requirements and limitations.
Test information
Technical details for FMR1 expansion test for Fragile X
Method, scope, requirements and limitations
Analysis of CGG repeats in the FMR1 gene by PCR and capillary electrophoresis, distinguishing normal, intermediate, premutation and full mutation ranges.
- Applications
- Rare and hereditary diseases
- Accepted samples
- Peripheral blood (preferred), Buccal swab, Extracted DNA
- Estimated turnaround time
- 15 calendar days, after order confirmation
- Methodology
- PCR amplification of the FMR1 promoter region containing the CGG repeats with the AmplideX PCR/CE FMR1 kit (Asuragen), followed by capillary electrophoresis on the Spectrum Compact CE System (Promega). The number of repeats is determined by automated analysis in the AmplideX PCR/CE Reporter software (Asuragen).
- Analytical scope
- Number of CGG repeats in the FMR1 gene, classified as a normal allele (fewer than 45 repeats), intermediate or gray zone (45 to 54), premutation (55 to approximately 200) or full mutation (more than 200 repeats).
- Genes analyzed
-
1 genes analyzed.
See full content
FMR1
- Medical order
- Required
Requirements
A medical order and sufficient clinical information to guide the analysis.
Limitations
Alleles in the full mutation range (more than 200 repeats) are not sized and are reported only as greater than 200 CGG repeats. In the normal to premutation ranges, a variation of up to 5%, up or down, in repeat size should be considered. Alleles with low-level mosaicism (below 5%) cannot be detected. The test does not assess methylation status or identify point or structural variants in the FMR1 gene.
Additional information
Genetic counseling is recommended. If the results are not consistent with the clinical findings, additional tests should be considered.
