Mutations of the Wilms’ tumor (WT1) gene have been shown to underlie a proportion of cases of Wilms’ tumor, an embryonal kidney cancer occurring mainly in childhood. The WTl gene comprtses ten exons spanning approx 50 kb of genomrc DNA. The messenger RNA is approx 3 kb in length and encodes a zinc finger protein. The four zinc fingers, which he at the C-terminal end of the protein, are encoded by separate exons 7–10. The 5′ end of the gene is extremely GC-rich, with areas approaching a 70% GC content. This makes this region difficult to amplify in polymerase chain reactions.
