Molecular genetics of the Wilms’ tumor plays an important role in the elucidation of the genetic etiology of the tumor disease generally. Contrary to the genesis of retinoblastoma, where a single gene is inactivated by two hits, the biological signalling pathways determining the origin of the Wilms’ tumor are more complex and several genes in several loci may participate. Formation of the Wilms’ tumor is accompanied with the most frequent genetic alteration, which is the loss of heterozygosity on the short arm of chromosome 11. It indicates inactivation of one or several tumor suppressor genes located at 11p region. The most studied gene of the Wilms’ tumor is WT1 gene, which has been cloned and sequenced. Biological function of WT1 protein is complex one and it requires probably an interaction with other proteins, DNA and also RNA. The development of the tumor determines not only the genetic changes, but also epigenetic changes, e.g., hypermethylation of promoter and genome imprinting.

        Key words: Wilms’ tumor, WT1 gene, candidate loci, epigenetic alterations