HLA and human mate choice: Tests on Japanese couples

House mice are apparently more likely to mate with individuals dissimilar to themselves at MHC (major histocompatibility complex) loci than with similar individuals. Such negative assortative mating is thought to be mediated by olfaction. Recently, it has been suggested that human mate choice may be affected by HLA (human leukocyte antigen; MHC in humans), based on the finding that women prefer the odor of men dissimilar to themselves at HLA loci to that of HLA-similar men. If these odor preferences are indeed an important criterion of mate choice in humans, actual marriages may show negative assortment with respect to HLA. In this paper, we compared the observed similarity between spouses at HLA loci with the expected similarity under random mating, for about 150 couples from 6 prefectures in the Tohoku region of Japan, and for about 300 couples from 16 prefectures all over Japan. For statistical tests, we used empirical distributions of goodness-of-fit statistics, X-2 and G, obtained by Monte Carlo methods, because these statistics may not follow the chi-square distribution. Tests for each sample as a whole and for each prefecture rule out strong disassortative mating at the HLA-A and HLA-C loci.