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First Direct-to-Consumer Genetic Test for Rare Disorder Wins FDA Nod
The FDA has authorized for marketing the 23andMe Personal Genome Service (PGS) Carrier Screening Test for Bloom Syndrome (23andMe, Inc.), a direct-to-consumer genetic test to determine whether a healthy person has a variant in a gene that could lead to their offspring inheriting the serious disorder.
Along with this authorization, the FDA is classifying carrier screening tests as class II. In addition, the agency intends to exempt these devices from FDA premarket review.
Bloom syndrome is a rare disorder that is more common in people of Central and Eastern European, or Ashkenazi, Jewish background. About 1% of people of Ashkenazi Jewish descent are carriers. The disorder is characterized by a short stature, sun-sensitive skin changes, and an increased risk of cancer. According to the National Institutes of Health, Bloom syndrome is inherited in an autosomal recessive pattern, which means that both copies of the gene in each cell have mutations.
The Carrier Screening Test for Bloom Syndrome is indicated for the detection of the BLMAsh variant in the BLM gene from saliva collected using an FDA-approved collection device (Oragene DX model OGD-500.001). The test can be used to determine the carrier status for Bloom syndrome in adults of reproductive age, but it cannot determine whether a person has two copies of the BLMAsh variant. The test is most relevant for people of Ashkenazi Jewish descent.
In general, carrier testing is a type of genetic testing performed in people who show no symptoms of a genetic disorder but may be at risk for passing it on to their children. A carrier for a genetic disorder has inherited one normal and one abnormal allele for a gene associated with the disorder. A child must inherit two abnormal alleles, one copy from each parent, for symptoms to appear.
But no test is perfect, the FDA says. Given the probability of erroneous results and the rarity of these mutations, professional societies typically recommend that only prospective parents with a family history of a genetic disorder undergo carrier screening. For example, when a gene mutation is expected to be very rare, a positive result for the mutation may have a high probability of being wrong.
Like other home-use tests for medical purposes, the FDA requires the results of the Carrier Screening Test for Bloom Syndrome to be conveyed in a way that consumers can understand and use. This is the same approach the FDA has taken with other over-the-counter consumer products, such as pregnancy, cholesterol, and human immunodeficiency virus (HIV) tests for home use.
While the FDA is not limiting who should or should not use the Bloom syndrome test, it is requiring the manufacturer (23andMe) to explain to consumers in the product labeling what the results might mean for prospective parents interested in seeing whether they carry a genetic disorder. The FDA is also requiring 23andMe to provide information to consumers about how to obtain access to a board-certified clinical molecular geneticist or equivalent to assist in pre- and post-test counseling.
23andMe performed two studies to demonstrate that their test is accurate in detecting a person’s Bloom syndrome carrier status. One study tested a total of 123 samples, including samples from known carriers of the disease, and the other study evaluated 105 samples. Both studies showed equivalent results in detecting the carrier status for Bloom syndrome when the same samples were tested.
The company also conducted a usability study in 295 people who were unfamiliar with the Oragene DX saliva-collection device to demonstrate that consumers could understand the test instructions and could collect an adequate saliva sample.
Finally, the company conducted a user study in 302 randomly recruited participants representing the U.S. general population in age, gender, race, and education level to show that the test instructions and results were easy to follow and understand.
According to the FDA, the Carrier Screening Test for Bloom Syndrome is intended only for postnatal carrier screening in adults of reproductive age, and the results should be used in conjunction with other available laboratory and clinical information for any medical purposes.
23andMe previously marketed a personal genome service in the U.S., but it ceased providing direct health information to U.S. consumers after the FDA issued a 2013 warning letter. The letter directed 23andMe to stop selling the product because of the company’s failure to obtain marketing clearance or approval to assure that its tests were accurate, reliable, and clinically meaningful.
Sources: FDA; February 19, 2015; and 23andMe, Inc.; February 19, 2105.