Fragile X with Reflex, Xsense(R)

Message

For New York patient testing, use test code 19758X.
This test was developed and its performance characteristics have been determined by Quest Diagnostics. Performance characteristics refer to the analytical performance of the test .
If PCR result is a carrier or abnormal male then Southern blot will be performed at an additional charge (CPT code(s): 83891, 83892 x2, 83894, 83897, 83896).
If PCR result is a carrier or gray zone female or has normal homozygous FMR1 alleles then Capillary Electrophoresis will be performed at an additional charge (CPT code(s): 83892 x2, 83909 x8, 83900 x4).
If Capillary Electrophoresis is abnormal then Southern blot is performed at an additional charge (CPT code(s): 83891, 83892 x2, 83894, 83897, 83896).

Test Code

19757X

CPT Codes
83891; 83900; 83909; 83894; 83912

Physician Attestation of Informed Consent

This germline genetic test requires physician attestation that patient consent has been received if ordering medical facility is located in AK, DE, FL, GA, IA, MA, MN, NV, NJ, NY, OR, SD or VT or test is performed in MA.

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)

Preferred Specimen

5 mL whole blood

Minimum Volume

3 mL

Other Acceptable Specimens

Acid citrate dextrose ACD-A-B (yellow-top), or sodium heparin (green-top) tube

Instructions

Room temperature

Transport Container

EDTA (lavender-top)

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 8 days
Refrigerated: 8 days
Frozen: Do not freeze

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Extensive hemolysis observed • Sample received frozen

Methodology
Polymerase Chain Reaction with Detection by Capillary Electrophoresis, Capillary Southern Analysis, Southern Blot Analysis

FDA Status
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.

Setup Schedule

Set up: Daily night; Report available: 12 days (5 days for PCR and 7 days additional if reflex required)

Limitations

This analysis evaluates only the size of the FMR1 CGG repeat and cannot detect other possible chromosomal or DNA abnormalities. This assay cannot rule out the possibility of Fragile X syndrome caused by any other type of mutation in the FMR1 gene. In addition, this assay may not detect a FMR1 CGG expansion that presents with low-level mosaicism (this means that the expansion is present in only some cells not all cells). DNA analysis can predict the occurrence of Fragile X syndrome, but not the severity of the condition.

Reference Range

See Laboratory Report

Clinical Significance

Fragile X syndrome is the most common cause of inherited mental retardation. The mutation responsible for the Fragile X syndrome involves the expansion of tandem trinucleuotide repeats in the Fragile X mental retardation (FMR-1) gene (GenBank GI:1668818) on the long arm of the X chromosome. It is a defect in the FMR1 gene on the X chromosome and seen in approximately one in 1,200 males and one in 2,500 females.

Performing Laboratory

Quest Diagnostics Nichols Institute-San Juan Capistrano, CA

33608 Ortega Highway

San Juan Capistrano, CA 92675-2042

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.