Aging Men Lose the Y Chromosome—and Health Risks Rise

As men age, many cells lose the Y chromosome, creating a mosaic of Y-bearing and Y-less cells. Loss frequency climbs with age (roughly 40% at age 60 and 57% by age 90) and is linked to higher risks of cardiovascular and neurodegenerative diseases, cancer, and even mortality in some studies, though causation isn’t proven. Environmental factors like smoking and genetic susceptibility influence Y loss. Some animal studies suggest Y deficiency can accelerate age-related pathology, and the Y’s regulatory and non-coding genes may impact gene expression and immune function, indicating the Y chromosome has functional roles beyond sex determination that merit further investigation.