[Chromosome changes associated with childhood leukaemia occur prenatally].

Leukaemia is the most common cancer in childhood, yet only a few risk factors have been identified. Studies of monozygotic twins with concordant leukaemia and retrospective analyses of neonatal blood spots from children with leukaemia indicate that chromosomal translocations characteristic of childhood leukaemia often occur prenatally. The chromosomal translocations may be initiators of the leukaemia development but per se are insufficient to cause the disease. The findings provide a basic understanding of the natural history of childhood leukaemia and may make the development of preventive measures feasible.