Bloom syndrome Wikipedia is a rare inherited disease that is found more often in Ashkenazi Jews than in other populations. One feature of Bloom syndrome is a high risk of cancer. Bloom syndrome is sometimes considered a disease of premature or accelerated aging. Wikipedia
More than 60 different mutations in the BLM gene can cause Bloom syndrome if a child inherits two copies of the same mutation, one from each parent. Carriers are not affected. About 1 percent of Ashkenazi Jews carry a particular mutation that is tested by 23andMe (i4000396, also known as rs113993962). The BLM(Ash) variant was found to increase risk of colon cancer in Ashkenazi Jews.