Researchers from University of Helsinki identify novel X-chromosomal genetic variants as the reason behind the difference in height between men and women.
Ever wondered why men are mostly taller than women. University of Helsinki researched revealed in a new press release that it may have something to do with X-chromosomal genetic variants in the body.
The X chromosome has a very unique nature. While women have two copies of this chromosome, men have only one. Studying the genetic variations associated with these chromosomes can help researchers better understand why some genes are different in both sexes. For the new study, researchers thoroughly analyzed the commonly occurring genetic variation in chromosome X, one of the two sex-determining chromosomes, in almost 25,000 Northern European individuals. Additional diverse health-related information related to these participants was also considered.
"Studying the X chromosome has some particular challenges. The fact that women have two copies of this chromosome and men only one has to be taken into account in the analysis. We nevertheless wanted to take up the challenge since we had a strong belief that opening 'the X files' for research would reveal new, interesting biological insights," said Dr. Taru Tukiainen who is currently working at the Massachusetts General Hospital in Boston.
ITM2A is a gene responsible for cartilage development. Researchers found that a genetic variant close to ITM2A is commonly found in people that are shorter than average. This identified the genetic variant increase the expression of ITM2A, which led researchers to state that the more the gene is expressed the shorter the person will be. Researchers observed that the effects of this variant is stronger in women than men.
"The double dose of X-chromosomal genes in women could cause problems during the development. To prevent this, there is a process by which one of the two copies of the X chromosome present in the cell is silenced. When we realized that the height associated variant we identified was nearby a gene that is able to escape the silencing we were particularly excited," explained Professor Samuli Ripatti, the principal investigator behind the study.
Researchers noted that identifying such variants and associated regions where X-chromosomal gene doses are not balanced between men and women, can be particularly valuable in helping us to understand why some characteristics differ between sexes, he added.
"Based on our calculations, this variant accounts for a significant, though small proportion, 1-2% of the current difference in mean height between men and women in the Finnish population," Ripatti said.
Findings of the study were published in PLOS Genetics journal.
