Y chromosome loss
It is not known whether the loss of the Y chromosome is the critical mutational event is a secondary genetic change, or if the critical genetic change occurs just by chance in a –Y cell. It is thought that the loss of the Y chromosome could provide a proliferative advantage by shortening the cell cycle. The presence of cells with loss of the Y chromosome (-Y) increases with age and is significantly higher in patients with myeloproliferative disorders (MPD), myelodysplastic syndromes (MDS) and acute non-lymphocytic leukemia (ANLL) in subjects who do not show the disease.
In MDS, according to various studies, the proportion of cells with loss of the Y chromosome (-Y) may increase, decrease, remain stable, or fluctuate. The prognosis, in this patients, appears to be neutral or favorable.