The first IVD for the diagnosis and screening of fragile X syndrome and other FMR1-related disorders
Austin, Texas — 02/24/2020 — Asuragen, Inc., a molecular diagnostics company delivering high-quality, easy-to-use products for complex testing in genetics and oncology, today announced that its AmplideX® Fragile X Dx and Carrier Screen Kit has been cleared by the United States Food and Drug Administration (FDA). The all-inclusive diagnostic kit reliably determines the number of cytosine-guanine-guanine (CGG) repeats in the fragile X mental retardation 1 (FMR1) gene to aid in the diagnosis of fragile X syndrome and associated disorders including fragile X-associated tremor/ataxia syndrome (FXTAS) and fragile X-associated primary ovarian insufficiency (FXPOI). The test is also indicated for use in screening asymptomatic carriers at-risk for having children with fragile X syndrome.
“AmplideX technology introduced a dramatic paradigm shift in how challenging repetitive sequences, like those within FMR1, could be routinely detected and analyzed,” said Elizabeth Berry-Kravis, MD, PhD, co-investigator of the study and co-director of the molecular diagnostics section of the genetics laboratory and professor of pediatrics and neurological sciences at Rush University Medical Center. “Enabling better access to testing to predict and diagnose these cases significantly improves our ability to make a difference in these patients’ lives by eliminating the diagnostic odyssey that many families experience and allowing more accurate genetic counseling.”
Fragile X syndrome testing is recommended by the American College of Obstetricians and Gynecologists (ACOG) 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. As a first-tier test for unexplained developmental delay, intellectual disability and autism, fragile X syndrome testing may be relevant to as many as 400,000 children in the US.
Fragile X syndrome is the most common inherited form of intellectual disability and autism, affecting an estimated 1 in 3,600 males and 1 in 4-6,000 females in the United States. Transmitted as an X-linked disorder, the condition is caused by a full mutation expansion (>200 CGG repeats) within the FMR1 gene. Three additional repeat categories are associated with FMR1 CGG testing: normal (5-44 repeats), intermediate (45-54 repeats), and premutation (55-200 repeats). Fragile X carrier screening requires accurate sizing of expanded alleles since some premutations have a high risk of expanding to a full mutation in the next generation. Fragile X has one of the highest genetic carrier rates across populations and more than one million female carriers are estimated in the US, most of whom remain unidentified.
“The ability to more accurately and reliably measure CGG repeats throughout the expanded range and particularly in the complex premutation zone combined with an efficient workflow represents a tremendous advantage to using the AmplideX Fragile X Dx and Carrier Screen Kit,” said Flora Tassone, PhD, co-investigator of the study, professor at the University of California Davis, and investigator at the UC Davis MIND Institute. “The test has helped improve our understanding of premutation-associated disorders including FXTAS and FXPOI cases, which have traditionally been more challenging to diagnose.”
The AmplideX Fragile X Dx and Carrier Screen Kit is the first and only test for the detection and quantification of expanded pathogenic repeat sequences to be cleared by the FDA. Based on the company’s proprietary AmplideX chemistry, the test is a simple and scalable PCR that identifies and sizes repeat expansions without requiring Southern blot analysis. Samples are analyzed from this PCR-only workflow within six hours using as little as 20 ng DNA. Analysis is streamlined by the included AmplideX Reporter software, which automates sample genotyping and delivers results from a full plate of samples in minutes. The diagnostic kit is approved for use on the Applied Biosystems™ 3500 Dx Genetic Analyzer and Applied Biosystems™ 3500xL Dx Genetic Analyzer, which were FDA-cleared for fragment sizing in parallel with this test.
Two multi-center clinical validation studies were conducted across three US clinical laboratory sites to establish a diagnostic claim and a screening claim for the AmplideX Fragile X Dx and Carrier Screen Kit on the approved capillary electrophoresis instruments. Diagnostic performance was assessed on a total of 207 samples and the positive percent agreement with Southern blot for full mutation detection was 95.7% with a 95% confidence interval of 88.1 – 98.5%. Carrier screening performance for detection of premutations or full mutations had a positive percent agreement of 100% (95% confidence interval of 94.7 – 100%).
“For nearly a decade, Asuragen has been at the forefront of putting routine investigation of the FMR1 gene within reach of laboratories everywhere,” said Matthew McManus, MD, PhD, president and CEO of Asuragen. “With this clearance, we not only demonstrate the robustness of our technology in meeting the requirements of the FDA, but also our commitment to making our tests clinically available to people throughout the world.”