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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: Fragile X by PCR

Test Code(s): SLH828 / HCSLH828

CPT Code(s): 81243, 81244

Clinical Significance: To identify Fragile X gene mutation in persons with sex linked mental retardation syndrome and possible carrier status.

Testing Site: Testing will be sent to an approved reference laboratory.

Days Performed: Mon-Sat.

Turnaround Time: Routine: 14 days.

Specimen Requirements

Specimen: Blood

Collection Instructions: Blood must be received and processed by WSLH within 48 hours of collection.  Blood must be received by the UWHC Core Laboratory  Monday-Friday.

Collection Container: Preferred: Lavender top

Collection Volume: Preferred: 6 mL
Pediatrics: 2 mL

Sample Analyzed: Whole Blood

Specimen Transport: Transport specimen to laboratory.  

Unacceptable Criteria: Whole blood that is clotted or frozen.  Plasma and serum are not acceptable.

Stability: Ambient: 48 hours
Refrigerated: 48 hours
Frozen: Not acceptable


Report provides interpretation.

Additional Information:

To rule out other cytogenetic causes, persons suspected of having the Fragile X Syndrome should first have chromosome studies. This is not required for relatives of persons previously studied by cytogenetics and molecular analysis who have been found to be Fragile X positive.


cytogenetics sex-linked mental retardation

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