Y Chromosome Loss in Childhood Leukaemias

S ummary . During the past 3½ years cytogenetic studies have been performed on all children with leukaemia prior to treatment. Loss of the Y chromosome documented by chromosome banding techniques, was observed in bone marrow blast cells from two of 11 consecutive male children. One patient had acute myeloblastic leukaemia of t(8;21) type. The other patient was diagnosed as acute lymphoblastic leukaemia. Our studies provide evidence that Y loss occurs in childhood leukaemias and is not necessarily related to an ageing process as suggested by others. Furthermore, this study demonstrates that Y loss can occur as a sole abnormality in non‐myeloid leukaemia.