Yale New Haven Hospital

Department of Laboratory Medicine
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Xsense(R), fragile X with reflex

Lab Section: 

Sendout Reference


Lab Location: 


Reference Lab: 



Test ID: 




Polymerase Chain Reaction (PCR) with Detection by Capillary Electrophoresis




2 weeks, additional 7 days if reflex required.

Specimen Requirements: 

Collection: 5.0 mL Blood in a Lavender Top Tube.
Pediatric volume: 3.0 mL.
Alternative Specimen(s):  ACD solution A (yellow-top), ACD solution B (yellow-top) or sodium heparin (green-top) tube
Normal phlebotomy procedure. Specimen stability is crucial. Store and ship room temperature immediately. Do not freeze.
Unacceptable conditions: Sample stored frozen
Stability: Refrigerated: 8 days, Ambient: 8 days, Frozen: unacceptable



Clinical Indications: 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.

Performing laboratory: Quest Diagnostics Nichols Inst-San Juan Capistrano 33608 Ortega Highway San Juan Capistrano, CA 92675-2042

Reference Interval: 

See patient report or consult reference laboratory website.



CPT Code(s): 


Last Changed: 

8/16/2017 11:17:15

Last Reviewed: 

8/16/2017 11:17:24