Hypolactasia in Saami subpopulations of Russia and Finland.

Primary hypolactasia is a gene attributed condition of the inability of adult individuals to consume whole milk. Subpopulations of the Russia (Kildin) and Finland Saami are characterized by a large variability of the LAC*R (lactase restriction) gene frequencies (0.50-0.77). The distribution of primary hypolactasia among the Saami is ranging from 25% to 60%. The intensive reindeer breeding was developed by the Saami only 300-400 years ago. Reindeer milk is poor in lactose (2.4%) and is consumed by the Saami in small amounts. Thus, "milk behaviour" connected with reindeer breeding could not have influenced the trait evolution too much. The large between-group differences of the LAC*R gene frequencies in the Saami seem to reflect the level of genetic influence of neighbouring non-Saami populations. The role of gene inflow in reducing the level of primary hypolactasia in various Saami subpopulations is confirmed by historic data of various ethnoterritorial groups as well as by the reduction of the number of traditional family name bearers and the change of the AB0 blood group gene frequencies among the Kildin Saami in the last 30 years.