Height differences between men and women have long been attributed to sex hormones, but a recent study has shed light on the role of genetics in this sexual dimorphism. Researchers from the U.S. analyzed a large dataset of adult participants, including individuals with sex chromosome aneuploidies (SCAs), to investigate the influence of extra X and Y chromosomes on height.
The study found that having an extra Y chromosome led to a greater increase in height compared to an additional X chromosome, regardless of the impact of male hormones. This difference in height can be attributed to genes located in the pseudoautosomal region 1 (PAR1) of the X and Y chromosomes, particularly the SHOX gene, which plays a key role in determining height.
In females, most of the X chromosome is inactivated, except for the PAR1 region, where genes like SHOX remain active. This partial silencing of genes on the X chromosome may explain why males with an extra Y chromosome have higher levels of SHOX expression compared to females with two X chromosomes, leading to differences in musculoskeletal development and ultimately height.
The researchers used multivariate linear regression to model the effects of the inactive X chromosome, the Y chromosome, male hormones, and genetic disorders on height. They found that the contribution of the Y chromosome to height was greater than that of an additional X chromosome, regardless of hormonal differences. This finding was consistent across diverse ancestry groups and could explain up to 22.6% of the average height difference between males and females.
Furthermore, pathogenic variants in the SHOX gene were found to have a more significant impact on height in males than in females. Understanding the genetic basis of sex dimorphisms, such as height differences, is not only important for uncovering the biological mechanisms behind these disparities but also for studying the occurrence of various medical conditions influenced by sex chromosomes.
This groundbreaking research provides valuable insights into the genetic underpinnings of height differences between men and women, highlighting the pivotal role of the Y chromosome in determining height. The study’s findings have significant implications for understanding sex-based disparities in human biology and health outcomes.
