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XSense®, Fragile X with Reflex

Test code

16313

CPT code(s)*

81243
Notices
**CPT Code is subject to a Medicare Limited Coverage Policy and may require a signed ABN when ordering.
Not offered in Quest Diagnostics Nichols Institute (IFD) – San Juan Capistrano. Please provide Service Area Information to find available tests you can order.
In-home collection is not available in your area through Quest Mobile.

Clinical significance

XSense®, Fragile X with Reflex - Fragile X syndrome (FXS OMIM # 300624) is the most common inherited mental retardation syndrome, affecting approximately 1:4000 males and approximately 1:8000 females. The disease is caused by the expansion of a trinucleotide CGG repeat in the 5'-untranslated (UTR) region of the FMR1 gene. Methylation of the expanded CGG tract leads to silencing of expression of the FMR1 gene. The American College of Medical Genetics defines a normal repeat length as between 5 and 44. Intermediate alleles of between 45-54 repeats almost never expand to full mutations in a single meiosis. Premutation alleles are defined as 55-200 CGG.…
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Test resources

Test FAQ

XSense, Fragile X with Reflex

Details

Test details

Includes

If Fragile X, PCR result is not Normal, or Gray zone, then Fragile X Methylation Analysis will be performed at an additional charge (CPT codes(s): 81244).

Methodology

Polymerase Chain Reaction (PCR) with Detection by Capillary Electrophoresis

Assay category

This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Alternative name(s)

FRAX,Fra(X),Fragile X with Reflex,Martin-Bell Syndrome,FMR1

Specimen requirements
Patient preparationNone Specified
Preferred specimen(s)4 mL whole blood collected in an EDTA (lavender-top), ACD (yellow-top), or sodium heparin (green-top) tube
Minimum volume3 mL
Collection instructionsWhole blood: Normal phlebotomy procedure. Specimen stability is crucial. Store and ship room temperature immediately. Do not freeze.
Transport containerOriginal collection tube
Transport temperatureRoom temperature
Specimen stabilityRoom temperature: 8 days
Refrigerated: 8 days
Frozen: Unacceptable
Reject criteriaExtensive hemolysis observed • Received frozen
Service Area Information
Service Area Information
Service Area Information

Reference ranges are provided as general guidance only. To interpret test results use the reference range in the laboratory report.

*The CPT codes provided are based on AMA guidance and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

This material contains content from LOINC® (http://loinc.org). The LOINC Table, LOINC Table Core are copyright © 1995-2019, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee and is available at no cost under the license at http://loinc.org/license.

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