Significance of abnormalities involving chromosomal segment 11q22-25 in acute leukemia.

Six hundred and thirty unselected cases of acute leukemia, with complete data regarding age, karyotype (with breakpoints), and the diagnosis according to the FAB classification, were available in the literature and from our unpublished cases for comparing the incidence of chromosomal abnormalities involving the long arm of chromosome #11 among age groups in acute nonlymphocytic leukemia (ANLL) and acute lymphocytic leukemia (ALL). A statistically highly significant difference (p less than 0.001) was observed between the incidence of ANLL cases with chromosome aberrations involving 11q22-25 in childhood (less than or equal to 15 years) versus that in adults (greater than 15 yr). This statistical difference was not only related to infant cases (less than or equal to 12 months), but also to cases of children over 1 year of age. The incidence of the 11q22-25 abnormality in childhood cases (greater than 1 yr to less than or equal to 15 yr) was statistically significant (0.025 less than p less than 0.05) when compared to the incidence in adult cases. The incidence of the 11q22-25 abnormality in infant cases was much higher when compared to that of older cases with either ANLL or ALL (p less than 0.001 in each leukemia). This trend was not observed in cases with the 11q11-21 abnormality and this may imply that the origin and meaning of the 11q11-21 abnormality may differ from that of the 11q22-25 abnormality. Twenty-three infants with acute leukemia (AL) with the 11q22-25 abnormality were available from previous reports and our unpublished case. The median ages of ANLL, ALL, and all AL cases were 16 weeks, 9 weeks, and 15 weeks, respectively. The tendency of the 11q22-25 abnormality to be common in infants with ANLL or ALL under 6 months of age may suggest that it has a close correlation with the origin(s) or mechanism(s) related to the occurrence of infant AL.