Novel mutation in Wilms' tumour 1 gene associated with steroid-resistant nephrotic syndrome.

We report the case of a paediatric patient with steroid-resistant nephrotic syndrome due to a novel dominant Wilms' tumour 1 mutation. The nucleotide change C1184A, identified in exon 9, results in amino acid substitution Ser395Tyr. Genotyping of parents and healthy controls indicated that this is a de novo mutation not present in healthy individuals. The affected amino acid is evolutionarily conserved and is located in a functionally important domain of the protein involved in DNA binding. Molecular modelling based on crystallography data indicated that the substitution would have a deleterious effect on the protein function.