Test Catalog

Test

Code
W199
Name
FRAGILE X W/ METHYLATION
Description

Alternative Names: FRAX, 38037, W199, Fragile X with reflex to Methylation
Includes: Result, Allele 1, Allele 2, Methylation, HGVS Nomenclature
Sample Type: Whole Blood
Preferred Container: EDTA (Lavender Top) Tube
Sample Volume: 5.0 mL
Minimum Volume: 1.0 mL minimum, does not allow for repeat testing
Handling Instructions: Refrigerated specimen after collection
Transport Temperature: Refrigerated
Specimen Stability: Ambient: 7 days; Refrigerated: 1 month; Frozen: 1 month
Testing Frequency: Monday, Thursday
Expected Turn Around Time: 7-9 days
Testing Facility: Ref Lab/ SRL
CPT Codes: 81243; 81244 added if reflexed
Note: Prior Authorization Required.
Alternate Sample Type: Purified DNA
Sample Quantity: 50 µL at 50 ng/µL (Minimum of 25 µL at a minimum concentration of 20 ng/µL)
Specimen Stability: Ultra-frozen: 45 Days
If nucleic acid is submitted for analysis, nucleic acid isolation must be performed in a CLIA-certified laboratory or a laboratory meeting equivalent requirements as determined by the CAP and/or CMS.
Additional Information: Fragile X syndrome (FXS, OMIM 300624), Fragile X tremor/ataxia syndrome (FXTAS, OMIM 300623) and fragile X-associated premature ovarian insufficiency (FXPOI, OMIM 300624) are diseases caused by the expansion of CGG sequences in the 5′ untranslated region of the Fragile X Mental Retardation 1 (FMR1, OMIM 309550, NM_002024.4) gene. Methylation status and X-inactivation in females may modify the risk and phenotype of these diseases in females as compared to males. In more than 99% of cases, FXS is caused by the deficiency or absence of FMRP caused by expansion of CGG repeats in the 5′ untranslated region of the FMR1 gene. Rare cases of FXS that are caused by deletions or point mutations in FMR1 are not detected by this assay. FXS is one of the most common heritable forms of mental retardation and is characterized by mild to severe intellectual disability. It may affect both males and females, but females typically have milder symptoms. The symptoms of FXS include hyperactivity, perseverative speech, social anxiety, poor eye contact, hand flapping or biting, and connective tissue anomalies. Adult males may have physical findings including macroorchidism, a long narrow face, prominent ears and jaw, and a single palmar crease. The American College of Medical Genetics (ACMG) recommends the following classification for CGG repeat lengths: normal (200). The SRL Fragile X report will include number of repeats and the ACMG classification, as well as interpretive comments specific to the patient result.