Cytogenetic features of juvenile chronic myelogenous leukemia.

Consistent chromosomal abnormalities have been described in several leukemic disorders, but relatively little is known about the cytogenetic features of juvenile chronic myelogenous leukemia (JCML). We report the serial cytogenetic findings over a 2-yr period for a patient with JCML. A large subtelocentric marker chromosome was noted in all metaphases throughout the course of his disease and provided evidence for a clonal etiology of JCML in this patient. Banding analysis identified this marker as a chromosome 8. to which most of the long arm of a chromosome 2 had been translocated. An abnormal chromosome 1 was also noted. The probable stem cell karyotype was 46,XY,t(2;8)(q21 ;q24). del(1 )(p33-’pter), dup(1 )(p2l -‘p32). Two subclones evolved from the stem line population at different times during the course of the disease. We reviewed the cytogenetic findings for 16 other patients with JCML at this institution and for 68 patients reported elsewhere. Over 80 % of these patients had normal karyotypes as determined by conventional techniques, and no consistent cytogenetic abnormalities were noted among those with an abnormal karyotype. JCML may be a heterogeneous disorder, with some patients clearly showing evidence of malignant clonal proliferation. A few of the patients with normal karyotypes may have transient or sustained failure of bone marrow maturation.