\u201cMeasuring the genetic proximity of Jewish couples using the same yardstick as American couples is a mistake,\u201d said Maya. \u201cSome level of genetic relatedness is expected among Jews, as the result of generations of marrying within the group. If we don\u2019t take that into account, we end up with false red flags that can lead to heartbreaking decisions, including unnecessary terminations.\u201d<\/p>\n
\t Illustrative. A pregnant woman, on May 26, 2011. (Yossi Zamir\/Flash 90)<\/p>\n Analyzing 15,000 genetic samples<\/p>\n Maya began her investigation several years ago after repeatedly seeing Jewish couples receive alarming genetic reports from overseas clinics unfamiliar with the unique genetic background of Ashkenazi Jews. To test her hypothesis, she partnered with Prof. Lena Sagi-Dain, chair of the Israeli Society of Medical Genetics and head of prenatal genetic services at Carmel Medical Center in Haifa.<\/p>\n Together, the researchers began to collect and then analyze around 15,000 genetic samples from Rabin Medical Center, including both blood and embryo data, in 2017.<\/p>\n They organized people in the study by ethnic background. In Israel, there are about 16 different ethnicities, with Jews coming from places like Bukhara, Iran, Kurdistan, Iraq, Syria, Lebanon, Libya, Afghanistan, Yemen and Ethiopia.<\/p>\n The researchers also studied Christian and Muslim Arabs, Bedouins, and Druze in Israel.<\/p>\n \t Illustrative. Yemenite Jews arriving at Ben Gurion Airport in 2012. (Moshe Shai\/ Flash90\/File)<\/p>\n Ancestors in small communities share more DNA<\/p>\n DNA comes in pairs, with one copy from the mother and one copy from the father. Sometimes, a stretch of DNA is identical on both copies. This is called a run of homozygosity or ROH. These stretches often happen when people\u2019s ancestors came from the same small community, so they share more DNA.<\/p>\n The team measured how much of each person\u2019s DNA contained stretches where both DNA copies are the same. The researchers found that the size and amount of these stretches were very different between groups.<\/p>\n Maya noticed that longer identical stretches often meant that a person\u2019s parents shared more distant relatives, which can happen in communities such as Jews who have married within the same group for many generations.<\/p>\n \t Human DNA strand (iStock by Getty Images)<\/p>\n Maya said the pattern of the DNA was not random, but rather connected to the group\u2019s shared history and ancestry.<\/p>\n The result of the study was a new algorithm that tailors risk assessment to the genetic profile of each specific population. Instead of relying on a rigid, one-size-fits-all cutoff, Maya said, the model calculates a personalized \u201ctrue risk threshold.\u201d<\/p>\n American and European guidelines for genetic risks are based on millions of people who come from different ethnic backgrounds, she said.<\/p>\n That means that what might be labeled as a problematic genetic match in one population might be fine in another.<\/p>\n \t Prof. Idit Maya, acting director of the Genetics Institute at Rabin Medical Center. (Courtesy\/Shlomi Yosef)<\/p>\n \u201cInstead of automatically flagging any similarity that crosses an arbitrary line, our model adjusts to the couple\u2019s ethnic-genetic background and issues a warning only when there\u2019s a real reason to be concerned,\u201d Maya explained.<\/p>\n The Israeli Society of Medical Genetics adopted the new model in late July, and it is expected to be incorporated into Israel\u2019s updated clinical guidelines.<\/p>\n Maya\u2019s new genetic model will reduce unnecessary concerns and \u201cprevent false alarms.\u201d<\/p>\n In some cases, she added, it might even save pregnancies that might otherwise have been terminated.<\/p>\n \u201cThis is a big step forward in personalized medicine \u2013 not just for individuals, but for entire communities,\u201d Maya said.<\/p>\n
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