Ashkenazi Jews are four times more likely to be affected by Crohn’s disease than any other group.
Researchers have identified five new genetic mutations associated with Crohn’s disease in Jews of Eastern European descent (Ashkenazi Jews) and say their findings may help explain why Crohn’s is nearly four times more prevalent in this group than in the general population.
Medical genetics of Jews is the study, screening and treatment of genetic disorders that are more common in particular Jewish populations than in the population as a whole. The genetics of Ashkenazi Jews have been particularly well-studied, resulting in the discovery of many genetic disorders that are associated with this ethnic group.
In contrast, the medical genetics of Sephardic Jews and Oriental Jews are more complicated, since they are more genetically diverse and there are consequently no genetic disorders that are more common in these groups as a whole; instead they tend to have the genetic diseases that are common in their various countries of origin.
Several organizations, such as Dor Yeshorim, offer screening for Ashkenazi genetic diseases, and these screening programs have had a significant impact, in particular by reducing the number of cases of Tay–Sachs disease.
Previous research pinpointed 71 genetic variants associated with Crohn’s disease risk in people of European ancestry. In this new study, Mount Sinai School of Medicine researchers compared almost 2,000 Ashkenazi Jews with Crohn’s disease to another 4,500 Ashkenazi Jews without the disease.
Up until now, the reason for the high likelihood of infection within the Ashkenazi group was unknown, but according to an online science journal, researchers have shed light on this phenomenon with the discovery of five new genetic mutations.
Different ethnic groups tend to suffer from different rates of hereditary diseases, with some being more common, and some less common. Hereditary diseases, particularly hemophilia were recognized early in Jewish history, even being described in the Talmud.
However, the scientific study of hereditary disease in Jewish populations was initially hindered by the shadow of the racist and unscientific ideas of eugenics and “racial hygiene”, which tried to describe various ethnic groups as inferior.
However, modern studies on the genetics of particular ethnic groups have the tightly-defined purpose of avoiding the birth of children with genetic diseases, or identifying people at particular risk of developing a disease in the future. Consequently, the Jewish community has been very supportive of modern genetic testing programs, although this unusually high degree of cooperation has raised concerns that it might lead to the false perception that Jews are more susceptible to genetic diseases than other groups of people.
However, most populations contain hundreds of alleles that could potentially cause disease and most people are heterozygotes for one or two recessive alleles that would be lethal in a homozygote. Although the overall frequency of disease-causing alleles does not vary much between populations, the practice of consanguineous marriage (marriage between second cousins or closer relatives) is common in some Jewish communities, which produces a small increase in the number of children with congenital defects.