Taken together, these data suggest that the genetic architecture (additive, dominant, X-linked) and/or the overall genetic contribution (heritability) significantly differs between males and females for a large number of quantitative phenotypes, many of which are risk factors for common diseases, consistent with other studies of sex-specific heritabilities of common disease-associated quantitative phenotypes45,46. Although this data set is limited to only 19 quantitative traits, it further suggests that X chromosome genes may contribute disproportionately more to common phenotypes and quantitative trait variation in males than in females, not unlike Mendelian disease genes. Indeed, subsequent studies supported these conclusions, demonstrating significant sex differences in estimates of the autosomal narrow heritability for 13 (of 539) cardiovascular disease associated quantitative traits in French Canadian families45, and for bone mineral density in a number of recent studies (reviewed in Karasik and Ferrari46).
