MULTIPLICATION OF CHROMOSOMES AND PRIMARY LEUKOCYTE NUMBER IN CHILDHOOD ALL AND HYPERDIPLOID KARYOTYPE

In the blast cells of children with acute lymphoblastic leukemia (ALL) more than 50 chromosomes can be observed in a quarter of cases. As a rule these children have a good prognosis. However, some of these pati ents develop a relapse of their basic disease. There is only poor info rmation about the significance of distinct additional chromosomes for the prognosis. The white blood cell count (WBC) at the time of diagnos is is a further very important prognostic factor in childhood ALL. The refore we compared the relation between trisomy of distinct chromosome s and the initial white blood cell count of 41 children with common AL L and hyperdiploid karyotype. The modal chromosome number ranged from 50 to 60 chromosomes. Most frequently, the chromosomes X, 4, 6, 8, 10, 17, 18 and 21 were multiplied. Additionally, in 25 of the 41 cases st ructural chromosome aberrations were observed. The average WBC was est imated as 9.6 Gpt/l with a range from 1.8 to 41.5 Gpt/l. The initial W BC was slightly increased in patients with the additional chromosome X , 6, 11, 12 or 19 and distinctly decreased in children with the additi onal chromosome 8 or 9 in their hyperdiploid blast cells. No patient w ith an additional Chromosome 9 showed a WBC higher than 10 Gpt/l and o nly 2 out of the 12 children with an additional chromosome 8 revealed an initial WBC higher than 10 Gpt/l. Additional structural chromosome aberrations were without influence on the WBC.