Fragile X Syndrome, PCR With Reflex to Southern Blot

CPT: 81243
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Test Details




Carrier screening for individuals who are pregnant or considering pregnancy and who have no family or personal history of fragile X syndrome, fragile X-related disorders (primary ovarian insufficiency, or late-onset ataxia) or unexplained intellectual disabilities, developmental delay, or autism.


Polymerase chain reaction (PCR) followed by capillary electrophoresis with reflex to Southern blot analysis for all positive samples

Additional Information

Fragile X syndrome is the leading cause of inherited intellectual disability, affecting approximately 1 in 4,000 males and 1 in 8,000 females. It is found in all ethnic groups, and can occur in families with no history of intellectual disability. Women may decide to have testing to find out if they are carriers, and therefore are at risk of having a child with fragile X syndrome. The carrier frequency in women is approximately 1 in 260. Fragile X test is commonly used for individuals at higher risk, including those that may be symptomatic or have a family history suggestive of fragile X syndrome.

Specimen Requirements


Whole blood


10 mL


Lavender-top (EDTA) tube or yellow-top (ACD) tube

Storage Instructions

Room temperature

Causes for Rejection

Frozen specimen; hemolysis; quantity not sufficient for analysis; improper container; unlabeled or mislabeled specimen

Clinical Information


American College of Obstetricians and Gynecologists Committee on Genetics. Committee Opinion No. 469: Carrier screening for fragile X syndrome. Obstet Gynecol. 2010;116(4):1008-10.20859177
Hagerman PJ, Hagerman RJ. The fragile X premutation: A maturing perspective. Am J Hum Genet. 2004 May;74(5):805-816.15052536
Jacquemont S, Hagerman RJ, Leehey MA, et al. Penetrance of the fragile X-associated tremor/ataxia syndrome in a premutation carrier population. JAMA. 2004 Jan 28; 291(4):460-469.14747503


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
511919 Fragile X, PCR reflex Southern 511927 Fragile X DNA 21759-6
511919 Fragile X, PCR reflex Southern 451853 Comment: 77202-0
511919 Fragile X, PCR reflex Southern 450394 Indication 42349-1
511919 Fragile X, PCR reflex Southern 451358 Result 41107-4
511919 Fragile X, PCR reflex Southern 450396 Interpretation 62365-2
511919 Fragile X, PCR reflex Southern 450397 Comments 48767-8
511919 Fragile X, PCR reflex Southern 450398 Method 49549-9
511919 Fragile X, PCR reflex Southern 450399 Director 48672-0
511919 Fragile X, PCR reflex Southern 450400 Fragile X Syndrome, PDF 36913-2
Reflex Table for Fragile X DNA
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 511913 Fragile X Southern Blot 511914 Fragile X Southern Blot 36913-2

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