Short height? Blame it on X chromosome
The secret to the differences between male and female traits - including body mass index (BMI), height, blood pressure and lipid levels - lies in chromosome X.
Researchers from University of Helsinki analysed the commonly occurring genetic variation in chromosome X in almost 25,000 northern European individuals to know some of the well-known differences between men and women in certain traits, such as height.
"We had a strong belief that opening 'the X files' for research would reveal new, interesting biological insights," said researcher Taru Tukiainen.
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, Tukiainen added.
The study showed that a genetic variant close to ITM2A - a gene that has a role in cartilage development - is frequent among the people being shorter than average.
Interestingly, the effect of this variant on height was shown to be much stronger in women.
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 realised that the height associated variant we identified was nearby a gene that is able to escape the silencing, we were particularly excited," said lead researcher Samuli Ripatti.
"Because both copies of ITM2A remain active, the gene is expressed in higher levels in women," he said in the study published in the journal PLOS Genetics.
(Posted on 08-02-2014)