Genetic origin of the Swedish Sami inferred from HLA class I and class II allele frequencies

Sami of northern Scandinavia are genetic outliers among European populations and their origin has been difficult to determine. In order to study the genetic origin of the Swedish Sami, we have performed high-resolution typing of the class I HLA-A and -B loci and the class II DRB1, DQB1 and DQA1 loci in the northern and southern Swedish Sami. Several of the common class I alleles in Sami (B * 0702, B * 1501, B * 4002 and A * 0301) are found at high frequency in other European populations. However, a number of class I and class II alleles (B * 4001, A * 2402, DRB1 * 0901 and DRB1 * 1101) in the Swedish Sami are characteristic of Asian populations. Admixture analyses indicate that 87% of the Sami gene pool is of European origin and that the Asian contribution is 13%. Our HLA analyses indicate a higher proportion of Asian ancestry in the Sami than shown by previous genetic studies.