Fragile X Analysis, Molecular Diagnosis
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| WSLH Department: | Cytogenetics |
| WSLH Test Code: | 828 |
| Day(s) Performed: | Monday-Friday 7:45 AM - 4:30 PM, Saturday 7:45 AM - 12:00 PM |
| Turn-around Time: | Approximately 10-14 days, with an average of 10 days. (Reports are issued Monday-Friday 7:45 AM - 4:30 PM) |
| Recommended Uses: | To identify expansions of the CGG repeats in the FMR1 gene in Xq27.3 associated with FMR1-related disorders (fragile X syndrome, fragile X-associated tremor/ataxia syndrome (FXTAS), and FMR1-related primary ovarian insufficiency (POI). |
| Contraindications: | |
| Additional Tests Performed: |
| Patient Preparations: | |
| Specimen Requirements: | Blood: 6 ml (preferred) - 2 ml (minimum) of peripheral blood in sterile EDTA (purple top) vacuum type tubes. Saliva: Isohelix™ Saliva Collection kit used according to manufacturer instructions. Buccal: Stabilized buccal swabs collected with SafeCollect kit (Zymo) according to manufacturer instructions. |
| Specimen Handling & Transport: | Store and transport specimens at room temperature (may transport with coolant during hot weather, >85 degrees F). DO NOT FREEZE. The laboratory must receive specimens within 24-48 hours of collection. |
| Collection Kit/Container: | |
| Collection Instructions: | Contact the laboratory (608-262-0402) to obtain desired collection kit. Draw blood using aseptic techniques into a sterile EDTA vacuum type tube(s). Invert tube(s) to mix. If using larger tubes, draw to full volume to avoid over-treatment with anticoagulant. Saliva/Buccal: Collect according to manufacturer instructions. |
| Unacceptable Conditions: | Blood must not be frozen or hemolyzed. Plasma and serum are not acceptable. |
| Requisition Form: |
Cytogenetics Lab Genetic Diagnosis Form #131
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| Required Information: | Laboratory regulations require the following minimum information to be provided on the requisition form for a specimen to be accepted for testing: Patient name or unique identifier; date and time of collection, patient date of birth and sex, specimen type/site of collection, test request(s), reason for referral, clinician name and UPIN/NPI, and address for reporting results. Please be certain that name/identifier on the form matches that on the specimen label. |
| Results Include: | FMR1 CGG expansion detected/not detected. Repeat size of alleles observed. |
| Limitations: | CGG-repeat-expansion full mutations account for >99 percent of cases of fragile X syndrome. Rare mutations in the FMR1 gene unrelated to CGG repeat expansion will not be detected by this assay. Allele drop out and non-detection may occur due to rare sequence variations within the primer regions. |
| Additional Tests Recommended: | The American College of Medical Genetics and Genomics (ACMG) has recommended that array comparative genomic hybridization (aCGH) is used as a first-line test in the evaluation of individuals with multiple congenital anomalies, non-syndromic intellectual and developmental disability, and autism spectrum disorders. This is not required in cases with a family history of documented Fragile X mutation. |
| Additional Comments: | Asuragen AmplideX mPCR |
| Methodology: | The number of CGG repeats in the 5'-untranslated region (5'-UTR) of the FMR1 gene is determined using triplet repeat-primed PCR followed by size analysis using capillary electrophoresis. The Asuragen, Inc. AmplideX FMR1 assay quantitates CGG repeat lengths up to 200 and identifies normal (5-44 repeats), intermediate (45-54 repeats), pre-mutation (55~200 repeats), and full mutation alleles (reported as >200 repeats) (Monaghan et al. 2013, PMID: 23765048). The presence of size mosaicism can be detected but is not quantifiable. Methylation status is characterized for all pre-mutation and full mutation alleles using methylation specific PCR. |
| Includes: | Determination of CGG repeat expansion in the 5' untranslated region (5' UTR) of FMR1. Initial analysis includes a screening assay which indicates presence of alleles greater than 55 repeats and a sizing assay which provides CGG repeat size up to 200 repeats. PCR analysis (screening or sizing) indicating the presence of an allele greater than 55 repeats is reflexed to methylation-specific PCR for characterization of methylation status. |
| CPT Code: | 81243 |
| Price: | For pricing information, please call 608-262-0402. |