An identical t(Y;1)(q12;q21) in two patients with myelodysplastic syndromes.

Two male patients with myelodysplastic syndromes, one with refractory anemia with excess blasts (RAEB), the other with chronic myelomonocytic leukemia both had in their bone marrow and peripheral blood cells the same abnormal karyotype 46,X,-Y, + der (Y)t(Y;1)(q12;q21). This abnormality produced trisomy for the 1q21-1qter region of chromosome 1. In addition to the t(Y;1), the patient with RAEB had a del(20)(q11) abnormality in separate CFU-GM and BFUe progenitor cell populations. The t(Y;1) clone of this patient underwent chromosomal evolution with the acquisition of trisomies for chromosomes 2, 6, 8, and 9. Cytogenetic analysis of serial peripheral blood samples showed that the t(Y;1) clone and its derivatives gradually replaced that with the 20q- abnormality. Metaphase cells trisomic for chromosomes 2, 6, 8, and 9 were found predominantly in the CFU-GM population and only rarely in BFUe colonies, suggesting that chromosomal evolution was largely confined to the granulocytic lineage.