In the largest genetic study of fibromyalgia ever conducted, 47,895 of 54,629 patients, or 87.7 percent, were female. The condition affects roughly 2 percent of people worldwide, and that lopsided ratio has been one of its defining features for as long as it has been recognized.
So the researchers did the obvious thing. They split the data by sex and looked for genetic differences that might explain the gap.
