Constitutional mutations in the WT1 gene in patients with Denys-Drash syndrome

The Denys-Drash syndrome is characterised by a typical nephropathy, genital abnormalities and also predisposes to the development of Wilms' tumor. These patients eventually go into end stage renal failure. A candidate Wilms' tumor gene, WT1, from the 11p13 chromosome region has recently been cloned. We have analysed the DNA sequence in constitutional cells from eight patients and have shown heterozygous mutations in six of them. Four of the mutations were in exon 9, all resulting in missense mutations. Three were at nucleotide position 1180 resulting in an arg > trp amino acid change. The other was at position 1186 converting an asp > asn in the predicted resultant protein. One patient had a missense mutation in exon 8, converting an arg > his. A single base pair insertion at nucleotide position 821 in exon 6 resulted in the generation of a premature stop codon in the last patient. We were unable to find a mutation in one patient despite complete sequencing of the genomic sequence of the gene. The last patient carried a constitutional deletion of the 11p13 region and no additional mutation was found. There was no obvious correlation between the type of mutation and phenotypic expression. These results further demonstrate that the WT1 gene is important in both the development of the kidney and the genito-urinary system.