Non-synonymous de novo gene mutations in Wilms’ Tumor: Identification and characterization of new variants of WT1 and WT2 loci in Indian Population
Wilms tumor (WT) is a complex pediatric disease involving both genetic and epigenetic factors. There is strong evidence that mutations at WT1 and WT2 loci are associated with the etiopathology of WT cases. In humans, large numbers of predisposition genes are distributed throughout the genome, and their functional aptitude has not been defined clearly in tumor biology. We examined new variants of WT1 and WT2 in WT cases in Eastern India by performing gene analysis using Sanger sequencing. The study was further extended to translate nucleotide variants into the corresponding amino acids to explore the mechanisms of tumorigenesis. Using bioinformatics tools, the WT1 locus showed single nucleotide substitutions in the sequence, i.e. TGT → CGT or ACC→GCC, resulting in changes in amino acids; i.e. arginine is replaced by cysteine or alanine by threonine, suggesting that these changes might either alter zinc finger DNA binding domains or be involved in the synthesis of altered proteins during tumor cell differentiation. Similarly, the WT2 locus showed non-synonymous de-novo gene mutations, CAC→TAA, TAT→TAA, TGA→ GGA, and these new variations correspond to either histidine or tyrosine or glycine, respectively, resulting in failure to regulate transcription, suggesting that these nucleotide sequences can be considered as “stop codons” or pre termination codons. In conclusion, we identified new variants of WT1 and WT2 loci, leading to truncated proteins that may play a role in tumorigenesis in WT cases.