A recent study has shown that some of the genes present in the Y chromosome increases the chances of heart disease by as much as 50%. Men inherit a higher risk of cardiovascular diseases directly from their fathers. This adds to the increasing evidence as to why men are more susceptible to heart disease, compared to women. Women also have the additional protection provided by the female hormone, estrogen.
This report is significant considering the fact that the Y chromosomes, which carry relatively few genes, was supposed to have a smaller role in inheritance of characters other than the male sexual traits. This highlights a new role for the male chromosome. According to Lisa Bloomer, who made the discovery as a third-year PhD student in the department of cardiovascular sciences at the University of Leicester in the U.K, this result will change the perception of inheritance and the importance of sex chromosomes.
In this study, published in The Lancet, DNA from more than 3,000 men were analyzed. The researchers studied 11 regions in the DNA of the Y chromosome in particular. The Y chromosome has the advantage in that it has not changed significantly during evolutionary history, and enabled the scientists to work out the ancestry of an individual. Worldwide there are 30 haplogroups, or groups sharing the same ancestry.
Results of the analysis show that men who developed heart disease were more likely to belong to the same haplogroup, which is haplogroup 1. This shows that being in haplogroup 1 increases the chance of heart disease by about 50% compared to those in other ancestral groups. The risk remained the same even after considering other factors, such as high blood pressure, cholesterol, smoking, diabetes, and obesity. Being in haplogroup 1 predicted higher chances of developing heart disease next to factors like HDL levels and whether or not a person is taking cholesterol-lowering medications. Present estimate shows that about 20% of men in Europe and 10% of men in US belong to haplogroup 1.
The study has also shown a small geographical difference in the lineage with Denmark, Norway, and Sweden, having more people in haplogroup 1 and southern countries like Spain, France and Italy showing lesser frequency. The number of people having coronary artery disease is greater in the North of Europe than in the South.
The study added further information on the activity of genes in the different ancestral groups. The results showed that genes responsible for the development of atherosclerosis are more active in haplogroup 1. Inflammation and immune function activities were also different in the different groups. Virginia M. Miller, PhD, a professor of physiology and surgery at the Mayo Clinic in Rochester, suggests that sex chromosomes, especially Y chromosome, matters when it comes to inheritance of diseases. She adds that family history is a strong predictor of heart diseases in men.