Mosaic loss of chromosome Y (mLOY) also known as loss of chromosome Y (LOY) occurs to many men in some cells due to aging. Instead of the expected 46,XY karyotype, the affected cells have a 45,X karyotype due to the loss of the Y chromosome.[1]
| Mosaic loss of chromosome Y | |
|---|---|
 | |
| The Y chromosome. | |
| Specialty | Medical genetics |
The occurrence of LOY was discovered in 1963.[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.[1] Unlike loss of autosomal chromosomes, loss of sex chromosomes except the one active X chromosome does not typically cause cell death. Elderly women also experience mosaic loss of chromsome X, but it is less common than LOY.[1]
LOY in a small proportion of leukocytes (white blood cells) has been associated with a number of diseases such as cancer, Alzheimer's disease, and cardiovascular disease. Why this is the case is not understood.[4] LOY can also occur in cells of the buccal mucosa and dorsolateral prefrontal cortex.[3]