A diagnostic test for fragile X syndrome (FXS) has been cleared by the Food and Drug Administration (FDA). The Amplidex® Fragile X Dx and Carrier Screen Kit (Asuragen) works by determining the number of cytosine-guanine-guanine (CGG) repeats in the fragile X mental retardation 1 (FMR1) gene.

The test is also indicated for use in screening asymptomatic carriers at risk for having children with FXS. It can also aid in the diagnosis of associated disorders including fragile X-associated tremor/ataxia syndrome (FXTAS) and fragile X-associated primary ovarian insufficiency (FXPOI). The FDA reviewed the test through the de novo classification process.

The AmplideX Fragile X Dx and Carrier Screen Kit is the first test to be FDA-cleared for the detection and quantification of expanded pathogenic repeat sequences. The clearance was based on results from 2 studies that assessed 207 samples. Results showed that the positive percent agreement with Southern blot for full mutation detection was 95.7% (95% CI, 88.1-98.5). Carrier screening performance for detection of premutations or full mutations had a positive percent agreement of 100% (95% CI, 94.7-100).

FXS testing is recommended by the American College of Obstetricians and Gynecologists for carrier screening for genetic conditions and is recommended by the American Academy of Neurology and the Child Neurology Society as part of the diagnosis and evaluation for autism spectrum disorder.

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The kit is not intended for use in fetal diagnostic testing, the screening of eggs obtained for in-vitro fertilization prior to implantation, or stand‐alone diagnoses of FXS.  

For more information visit asuragen.com.