The role of hereditary factors in phenotypic variability of hormone levels in the population genetically adapted to circumpolar environment.

The variability of the plasma cortisol, T3, T4, TSH and estradiol levels were studied in the North Khanty population genetically adapted to the extreme conditions of the North. The relationships between genetic markers and hormone concentrations were also studied. Negative linear correlations of T3 and T4 levels with age were obtained. Cortisol, estradiol and T3 levels showed nonlinear age dependency. T4 concentrations were significantly lower in August than in February and November. The highest heritability estimate was shown for estradiol levels (44%).