Digit ratio links prenatal hormone exposure with adult lung function

Abstract

1measured the lung function of South Korean males and females who were hospitalized for an unrelated surgery. Information about smoking habits was collected and digit ratios were measured. They found a positive correlation between digit ratio and lung function, and secondarily, that the association was more robust in males than in females, evidenced by the fact that correlations between parameters of lung function and digit ratio persisted only for males when multivariate analyses were performed. Additionally, the relationship between digit ratio and lung function disappeared in smokers, indicative of the relatively greater influence of smoking on lung function. The authors concluded that low digit ratios predict poor lung function. To further evaluate the findings, it is helpful to place the results in context with other digit ratio studies. Although digit ratio is regarded as a sexually dimorphic trait, differences between the sexes are small and ranges are overlapping. In virtually every report of significant sex differences, male digit ratio is lower than female digit ratio (more testosterone produces lower digit ratio). However, the present study found male values (0.955 ± 0.035) to be higher than female values (0.936 ± 0.030); the reason for the low female ratios is unclear. Race and ethnicity are also known to influence digit ratios. In one study comparing ethnic differences in children, a different Oriental (Han) population showed sex differences in digit ratio in the expected direction (males lower than females) with males averaging