Medical genetics of Jews

The medical genetics of Jews is the study, screening, and treatment of genetic disorders 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 associated with this ethnic group. In contrast, the medical genetics of Sephardic Jews and Mizrahi Jews are more complicated, since they are more genetically diverse and consequently no genetic disorders are more common in these groups as a whole; instead, they tend to have the genetic diseases 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.

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 scientific racism, which is based on racial supremacism.

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.

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