The 10 coding exons of the WT1 gene, from 39 bp upstream of the transl
ation initiation codon to 12 bp downstream of the stop codon, were exa
mined for point mutations in a panel of 48 sporadic childhood acute le
ukaemias using the single-stranded conformational polymorphism (SSCP)
assay. The panel included 33 cases of acute lymphocytic leukaemia and
15 cases of acute myeloid leukaemia. This is the first study in which
sporadic childhood leukaemias have been examined for WT1 point mutatio
ns across the entire coding region of the WT1 gene, however, no tumori
genic point mutations or small deletions or insertions could be identi
fied in these patients. A previously described polymorphism in exon 7,
resulting in an A to G transition in an arginine codon, was observed
at a frequency of 21.5%, equivalent to that seen in the normal populat
ion. This study suggests that point mutations in the coding regions of
the WT1 occur infrequently in leukaemias of childhood.