The significance of isolated Y chromosome loss in bone marrow metaphase cells from males over age 50 years.

To further investigate the potential clinical significance of Y chromosome loss as the sole bone marrow karyotype change, we studied 161 Mayo Clinic male patients with 75% or more metaphase cells with Y loss, and correlated the percent Y loss with age and hematopathologic review. In patients with a lymphoproliferative or plasma cell disorder, the negligible proportion of bone marrow involvement cannot account for the observed high proportion of -Y cells. In males with myeloid disease, Y loss appears to often represent the abnormal myeloid clone, which may also harbor acquired genetic changes that are not observed by conventional cytogenetic analysis.