Loss of Y chromosome in patients with hematological disorders. E. Shin¹, L. Zhang³, Z. Yu², H. Tian², Y. Fei², R. Aldrich², J.J. Mulvihill², S. Li². 1) Department of Pediatrics, OUHSC, Oklahoma City, OK; 2) Department of Pathology, OUHSC, Oklahoma City, OK; 3) Department of Hematology, the First Teaching Hospital of China Medical University, Shenyang, P.R. China.
   To investigate whether a loss of Y chromosome is an age related phenomenon or a cytogenetic marker indicating a malignant change, we have studied twenty-four patients with a median age of 73 years-old (range 41-87) from a cohort of 592 consecutive male patients referred to us for chromosome evaluation because of hematological disorders. Two patients had acute myeloid leukemia (AML), 2 patients had chronic myeloid leukemia (CML), 2 patients had chronic myeloproliferative disorder (MPD), 3 patients had multiple myeloma, 5 patients had lymphoma, and 10 patients had myelodysplastic syndrome (MDS). Conventional cytogenetics studies were carried out according to our standard laboratory protocols. Fluorescence in situ hybridization (FISH) analysis was also performed utilizing DNA probes specific for the centromeres of chromosomes X and Y. The probes were purchased from a commercial source (Vysis, Downers Grove, Illinois, USA) and the tests were performed according to the manufacturer's protocols with minor changes. Twenty-one out of 24 patients had a loss of Y chromosome as sole anomaly and the remaining three had a loss of Y chromosome accompanied with other structural changes by conventional cytogenetic analysis. FISH analysis confirmed the routine cytogenetic results. All 24 patients had a loss of Y chromosome with a range of 17.5-98.5% of cells. Two of the patients one with AML and another with CML, had karyotype and FISH testing done both at the initial diagnosis and in the remission, and showed a loss of Y chromosome at initial diagnosis and had normal 46,XY karyotype during remission. In this study, it is demonstrated that the loss of Y chromosome is associated with a neoplastic change.