Mutations/deletions of the WT1 gene, loss of heterozygosity on chromosome arms 11p and 11q, chromosome ploidy and histology in Wilms' tumors in Japan

Incidence rates of Wilms' tumor (WT) markedly differ in East Asian and Cauc asian children. In the present study, we examined WTI deletions/mutations a nd loss of heterozygosity (LOH) on I I p and I Iq in a large number of WTs and compared our findings with those from 4 series of Caucasian WTs. Incide nce rates of the subtle WTI mutation in 3 of the 5 series of sporadic and u nilateral WTs including ours were 4.3-6.2% and similar. However, gross homo zygous WTI deletion was more frequent in our series than in some others. In addition, our series tended to show a higher incidence of LOH limited to I I p 13 and a lower incidence of LOH including I I p IS than the Caucasian one. These findings indicate some genetic differences in WT between the 2 r egions. One of the 4 Caucasian series reported a correlation of germinal WT I mutation with the predominantly stromal histology. The present study not only confirms the correlation of germinal WTI deletion/mutation with predom inant stromal histology but also establishes a correlation with somatic WTI deletion/mutations with predominant stromal histology. While WTs with WTI abnormalities usually showed pseudo-diploidy and predominant stromal histol ogy, those without WTI abnormalities showed various chromosome numbers and histologic subtypes. (C) 2001 Wiley-Liss, Inc.