Lactase deficiency in Russia: multiethnic genetic study.

Background: Lactase persistence-the ability to digest lactose through adulthood-is closely related to evolutionary adaptations and has affected many populations since the beginning of cattle breeding. Nevertheless, the contrast initial phenotype, lactase non-persistence or adult lactase deficiency, is still observed in large numbers of people worldwide.

Methods: We performed a multiethnic genetic study of lactase deficiency on 24,439 people, the largest in Russia to date.