| Summary: | This project produced novel findings regarding the association between genotype and human fertility, advanced new methods for studying hormonal and genotypic variation, and contributed the groundwork for subsequent research on the environmental, behavioral, and genetic determinants of reproductive hormone concentrations in arctic women. Individual differences in fertility are partly dependent upon a woman's reproductive hormone levels during her menstrual cycle. These hormone concentrations are also risk factors for several diseases (e.g., breast and other cancers, cardiovascular disease). Despite the significant roles of these hormones in women's health, very little is known about the extent and causes of variation in these hormones among pre-menopausal arctic women. This project examined whether genetic variation contributes to differences in fertility and hormonal variation in circumpolar ancestral (Central Asian) and descendant (indigenous South American) populations, and between former East and West German women. The specific characteristics of each of these population made them particularly suitable choices for this study. Contemporary Germany is very similar to the U.S. but had been divided for about 40 years into two separate countries with different lifestyles. Thus, Germany is both a good model for understanding hormonal variation in the U.S. population, and also allows a comparison of the effects of the different lifestyles on hormone concentrations in these genetically comparable German samples. Likewise, the Bolivian Aymara and Central Asian populations are genetically similar because of their shared ancestry with circumpolar populations, but their different lifestyles and environments are likely to influence hormone concentrations. We identified a significant SNP, exm562556 (rs34068461), associated with variation in fertility (fertility highest in GG genotype than in GT genotype which was higher than TT genotype). This variant is in a gene that encodes a protein thought to be involved in centrosomal or ciliary functions. Mutations in this gene also cause Leber congenital amaurosis type V, a syndrome including congenital blindness. The field, laboratory and analytical techniques advanced in this project are now being used in a study of the impact of arctic environmental conditions (most notably, the extreme seasonal variation in photoperiod) on Icelandic women's physiology and behaviors including reproductive and immune functioning, sleep repertoires, energy expenditure, dietary patterns, and psychosocial well-being.
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