Mosaic loss of chromosome Y (mLOY) also known as loss of chromosome Y (LOY) occurs to many men in some cells due to aging.

[2] "Age, genetic variants, ChrY structural aberrations and environmental stressors" such as smoking tobacco are all risk factors for developing LOY.

[1][3] The prevalence increases exponentially with age[3] and more than 40 percent of men over 70 are affected.

Elderly women also experience mosaic loss of chromsome X, but it is less common than LOY.

[4] LOY can also occur in cells of the buccal mucosa and dorsolateral prefrontal cortex.