Chromosome abnormalities in chronic myeloid leukemia in children.

Banded chromosomes of leukemic cells were studied in 53 children with chronic myeloid leukemia (CML). Ph1 chromosome was found in 21 children, and the remaining 32 cases were Ph1 negative. Besides Ph1 translocation additional chromosomal abnormalities, including marker i(17q), were revealed in three of eight children studied in blastic crisis of Ph1 positive CML. Leukemic cells of most patients with Ph1 negative CML possessed normal karyotype. Clones with chromosomal abnormalities were found in 12 of 32 cases. Most characteristic were monosomy 7 (in four children) and trisomy 8 (in three). Abnormal karyotype may be a bad prognostic sign in Ph1 negative CML. The presented data confirm the difference in age of appearance, bone marrow pattern and clinical course between Ph1 positive ("adult") and Ph1 negative (juvenile) types of CML in children. Probable prenatal commencement of CML in babies and children in the first years of life is discussed.