Hidden chromosomes are a health danger for men

Sex chromosomes determine our biological sex. Men typically have one X and one Y chromosome, while women have two Xs. But it isn’t straightforward, some men also have an extra X or Y chromosome – XXY or XYY.

- DR MIRIAM STOPPARD

In fact, around one in 500 men could be carrying an extra X or Y chromosome that puts them at an increased risk of diseases such as type 2 diabetes, atherosclerosis (hardening of the arteries) and thrombosis, say researchers at the universities of Cambridge and Exeter.

Their findings come from analysis of genetic data on more than 200,000 men aged 40-70 from UK Biobank. Scientists found 356 men carrying either an extra X chromosome or an extra Y chromosome.

An extra X chromosome can show as delayed puberty and infertility and an extra Y chromosome tends to occur in taller boys and adults.

The researchers identified 213 men with an extra X chromosome and 143 men with an extra Y chromosome.