[Chromosome abnormalities in leukemia in children. Occurrence and clinical significance].

In the last decade, specific chromosomal abnormalities were found in leukemic cells in children, which had diagnostic or even prognostic significance. Adult type chronic myeloid leukemia is associated with the Philadelphia chromosome (Ph1, t(9;22)), acute myeloid leukemia with maturation with t(8;21), acute promyelocytic leukemia with t(15;17), (myelo)-monocytic leukemia with abnormalities of chromosome II, and acute monoblastic leukemia with t(9;11). B-cell acute lymphocyte leukemias are associated with a t(8;14) or some other t(8q); in the other forms of acute lymphocytic leukemias a t(4;11) or 6q- is sometimes found. The presence of a t(8;21) seems to be associated with a better prognosis. In lymphocytic leukemias the presence of 50 or more chromosomes seems to predict a favourable prognosis, while, on the contrary, the presence of any translocation indicates a grave prognosis.