Fragile X, PCR and Southern Blot Analysis

CPT: 81243; 81244
Updated on 11/2/2017
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Test Details

Synonyms

  • FRAXA

Use

Diagnostic testing for:

• Unexplained intellectual disabilities, developmental delay, or autism

• Women with primary ovarian insufficiency or failure, premature menopause, or infertility associated with elevated FSH levels before the age of 40 with no known cause

• Individuals with late onset intention tremor and/or cerebellar ataxia of unknown origin

Methodology

Polymerase chain reaction (PCR) followed by capillary electrophoresis and Southern blot analysis performed on all samples at the same time

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

Specimen

Whole blood

Volume

10 mL

Container

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

References

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

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
511655 Fragile X, PCR and Southern 511596 Fragile X DNA 21759-6
511655 Fragile X, PCR and Southern 451853 Comment: N/A
511655 Fragile X, PCR and Southern 450394 Indication 42349-1
511655 Fragile X, PCR and Southern 451358 Result 41107-4
511655 Fragile X, PCR and Southern 511914 Fragile X Southern Blot 36913-2
511655 Fragile X, PCR and Southern 450396 Interpretation 62365-2
511655 Fragile X, PCR and Southern 450397 Comments 48767-8
511655 Fragile X, PCR and Southern 450398 Method 49549-9
511655 Fragile X, PCR and Southern 450399 Director 48672-0
511655 Fragile X, PCR and Southern 450400 Fragile X Syndrome, PDF 36913-2

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