Test, and Then Test Again, Experts Advise
With additional mutations for genetic diseases continuing to be discovered among Ashkenazi Jews, genetic screening advocates are urging people to get tested for newly identified diseases, even if they have already been tested for other diseases.
Some people may assume that since our genetic make-up is fixed, a DNA test is something that needs to happen only once. But experts recommend that Ashkenazi Jews should avail themselves of the new genetic information that becomes accessible over time by getting re-tested as new mutations are found.
“Even if you were screened two years ago, even one year ago — before each baby, check back,” said Faye Shapiro, genetic counselor at the Victor Center for the Prevention of Jewish Genetic Diseases. “Maybe there haven’t been any new diseases added, but if there have been, get re-screened for what you haven’t been screened for.”
The American College of Medical Genetics released a statement several years ago that outlined three major criteria that should be met in order for a test to be included in a battery administered to a given target population. First, a disease must be severe enough that it would affect someone’s reproductive choices. Second, the carrier frequency must be at least 1 in 100 in the target group. Third, the accuracy of the detection test must be 90% or higher.
Conforming largely, though not exclusively, to these criteria, many screening advocates are now encouraging Ashkenazi Jews to be tested for 18 diseases, a number that has risen from nine in recent years, due to new mutation discoveries and carrier screening advances. (The new number includes the newly discovered mutation for Joubert syndrome, for which screening will soon be more widely available.)
The Victor Center, along with other organizations that specialize in genetic diseases, is trying to rid its public of the outdated notion that getting tested once is enough. “People need to be screened and re-screened to remain consistent with new tests,” said Debby Hirshman, national director of the Victor Center. “Our website has always said that.”
Shapiro recounted hearing terrible stories from couples who were shocked when a second (or third, or fourth) child was born with a genetic disease — especially with one that might have been detected, if only the couple had been tested again. “We absolutely want people to realize that screening for new diseases has become available,” she said.
Dr. Harry Ostrer, director of the pediatric genetics program at New York University Langone Medical Center, agreed. “They’ll think they were tested for everything, and then they may find out they weren’t,” he said. “They’ll find themselves blindsided.”