One in 500 men carry extra sex chromosome, research suggests

Prevalence in UK study twice as high as thought, putting them at higher risk of health issues

Twice as many men carry an extra sex chromosome as previously thought, according to researchers who called for more genetic testing to identify people at greater risk of related medical problems.

Research on more than 200,000 men enrolled with the UK Biobank suggests that about one in 500 in the general population has an extra X or Y chromosome, double the number found in earlier work, though only a fraction are likely to be aware of it.