Fragile X Syndrome Testing

Fragile X Syndrome Testing 

Fragile X syndrome is the most common form of inherited intellectual disability.  Fragile X syndrome occurs among all ethnic backgrounds and racial groups. Approximately 1 in 260 women in the general population are carriers of fragile X syndrome. Additionally, women of all ages can have a child affected with fragile X syndrome, regardless of whether they have had previous healthy children.

  • a family history of fragile X syndrome
  • a family history of unexplained mental retardation, developmental delay or autism
  • infertility problems associated with elevated follicle stimulating hormone (FSH) levels, premature ovarian failure (POF) or unexplained early menopause

Collection Procedure

Peripheral blood sample collected in a purple top tube (EDTA) labeled with patient’s name and date of birth.  A completed test requisition form must be included with every sample.  A transport kit is available upon request.

Specimen Requirements

Adult: 20 ml whole blood.

Child: 5-7 ml whole blood.
Specimen Container 

Purple top tube (EDTA) 


Laboratory testing Fragile X Syndrome involves highly sensitive PCR analysis, with reflex to Southern blot for all positive samples to determine the number of CGC repeats present in the Fragile X gene located on chromosome X.

Transport Temperature

Room temperature (DO NOT refrigerate, freeze or centrifuge)
Causes for Rejection

Frozen specimen, clotted or hemolysed, inappropriate container
Turnaround Time

7-10 days