Abstract
Chromosomes were studied on diagnostic bone-marrow samples from 39 children with acute lymphoblastic leukaemia (ALL). The patients were classified, according to the chromosomal characteristics of the major proportion of their leukaemia cells, into five categories; hyperdiploid, pseudodiploid, diploid, hypodiploid, and mixed. Patients in the hyperdiploid category had significantly longer first remissions than those in all other categories, and those in the pseudodiploid category had the shortest. Neither the absence of any normal cells nor the presence of detectable clones appeared to be an adverse feature. We suggest that the proportion of hyperdiploid cells, determined by conventional chromosomal staining techniques, may be used as an additional prognostic feature in childhood ALL.