“It must have been your X”

Photo from: http://www.livescience.com/22179-evolutionary-battle-sexes-height.html

In this day and age when the Pope claims that there’s nothing wrong with LGBT, when sexuality and gender rights in some countries is much of a national concern, and when women’s rights advocates are going over the top by also being anti-men, talks about gender and sex have become a sensitive matter. Putting biology aside, gender and sex may mean a lot of different things depending on the context, culture, belief and philosophy of an individual. But what we can’t dispute is the fact that males and females are determined genetically (from here starts the science part) by the presence or absence of the chromosome Y. On the contrary, absence of the X chromosome is fatal because it contains a lot more loci (and therefore, genes) than the Y chromosome (which is also why X is significantly larger than Y), and losing it may mean losing the codes for processes essential for survival. More strangely though, scientific research neglected this chromosome in wide-scale genetic studies. However, very recently, researchers from the University of Helsinki in Finland decided to probe the X-chromosome to understand characteristics that differ between sexes. This year, they found novel X-chromosomal genetic variants that influence human height. So, why are men generally taller than women?

Through studying 25000 Northern European individuals with diverse health-related information, researchers analyzed the commonly occurring genetic variation in the X-chromosome. Their study showed that a genetic variant close to ITM2A, a gene found in the X chromosome and has a role in cartilage development, is frequent among individuals that are shorter than average. It also showed that the more the gene is expressed, the shorter the person will be. They found that, evidently, this variant was more strongly expressed in women. More interestingly, this gene escapes the silencing that is imposed in one of the two copies of the X chromosome in each cell. Because both copies of ITM2A remain active, it is expressed in higher levels in women.

Probing more on the difference of men and women on the molecular level can help us discover how and why some characteristics differ between sexes. This study was one of those that hopefully influence other researchers to probe deeper into the matter. Through these new knowledge, each one of us may be able to understand deeply why men and women are different. This may be the key for us to think more critically and rationally about the changing reputation of the different gender classifications. For someone who takes gender issues seriously, it may not be far-fetched to take the scientific aspect of the matter into consideration.

Blogpost by: Franzelle P. Padilla

References:

Helsingin yliopisto (University of Helsinki). Opening 'the X-files' helped researchers to understand why women and men differ in height. ScienceDaily. ScienceDaily, 7 February 2014. <www.sciencedaily.com/releases/2014/02/140207083836.htm>.

Taru Tukiainen, Matti Pirinen, Antti-Pekka Sarin, Claes Ladenvall, Johannes Kettunen, Terho Lehtimäki, Marja-Liisa Lokki, Markus Perola, Juha Sinisalo, Efthymia Vlachopoulou, Johan G. Eriksson, Leif Groop, Antti Jula, Marjo-Riitta Järvelin, Olli T. Raitakari, Veikko Salomaa, Samuli Ripatti. Chromosome X-Wide Association Study Identifies Loci for Fasting Insulin and Height and Evidence for Incomplete Dosage Compensation. PLoS Genetics, 2014; 10 (2): e1004127 DOI: 10.1371/journal.pgen.1004127