Mosaic loss of the Y chromosome and men's health

BACKGROUND: Although Y chromosomal genes are involved in male sex development, spermatogenesis, and height growth, these genes play no role in the survival or mitosis of somatic cells. Therefore, somatic cells lacking the Y chromosome can stay and proliferate in the body. METHODS: Several molecular technologies, including next‐generation sequencing and multiplex PCR‐based assays, are used to detect mosaic loss of the Y chromosome (mLOY) in the blood of men. MAIN FINDINGS: Accumulating evidence suggests that mLOY represents the most common acquired chromosomal alteration in humans, affecting >40% of men over 70 years of age. Advanced age, tobacco smoking, and some SNPs in cell cycle genes are known to increase the frequency of mLOY. The developmental process of mLOY in elderly men remains to be clarified, but it possibly reflects recurrent mitotic elimination of Y chromosomes or clonal expansion of 45,X cell lineages. In rare cases, mLOY also occurs in young men and fetuses. MLOY has been associated with early death, cancers, and other disorders in elderly men, infertility in reproductive‐aged men, and developmental defects in children. CONCLUSION: Y chromosomes in men can be lost at every life stage and Y chromosomal loss is associated with various health problems.