[Correlation of karyotype with clinical features in childhood acute lymphoblastic leukemia]

The karyotype of 124 children with acute lymphoblastic leukemia (ALL), who were diagnosed on the basis of the FAB classification, were studied according to numerical, structural abnormalities and the presence or absence of translocations. Clonal chromosome abnormalities were found in 85 (68.5%) of the 124 patients. Firstly, chromosome abnormalities were classified according to modal number. Twenty-four patients with ALL had hyperdiploidy (51-66 chromosomes). They had favorable prognostic factors, including low leukocyte count, age between 2 and 10 years and a low level of serum LDH. They had the most favorable outcome. Thirty-nine patients with normal karyotype had a relatively favorable outcome. In contrast 8 patients with near hyperdiploidy (47, 48 chromosomes), 47 with pseudodiploidy, and 4 with hypodiploidy (45 chromosomes) had a poor outcome. Secondly, chromosome abnormalities were also classified according to specific structural abnormalities. The 1; 19 translocation, which is associated with the pre-B phenotype, was found in 13 patients. Their outcome was better than has hitherto been reported. The abnormality of the short arm of chromosome 12 was found in 11 patients, who had a good outcome. The chromosome abnormality of the breakpoint in the T-cell receptor gene locus, containing bands 14q11 and 7q35, was found in 7 patients. Four patients had mediastinal tumors and the T phenotype. Their outcome was intermediate. The 14q32 translocation was found in 8 patients. The 8; 14 translocation was closely associated with L3 (FAB) and the B phenotype, but another 14q32 translocation was not. Their outcome was poor. The 11q23 translocation was found in 4 Patients, who had null cell blasts. Three of the 4 had unfavorable prognostic factors, including both a high leukocyte count and age under one year. They had a poor outcome. The partial deletion of the long arm of chromosome 6 was found in 4 patients. The structural abnormality of the short arm of chromosome 9 was found in 4 patients with absence of T cell phenotype. Two patients had a mass. Prognosis of the patients with 6q- and 9p abnormalities was unclear because of the small number of cases. Thirdly, chromosome abnormalities were also classified according to the presence or absence of translocations. The chromosomal translocations, which have an adverse effect in ALL (p = 0.004), were ones of the strongest predictor of treatment outcome. This study demonstrated that chromosome modal number, specific structural abnormalities and the presence or absence of translocations were significantly correlated with clinical features and survival rates of Japanese childhood ALL.