ENU-induced C to G transversion at base pair 53,771,322 (v38) on chromosome 11, or base pair 1,294 in the GenBank genomic region NC_000077. The mutation corresponds to residue 303 in the mRNA sequence NM_008390 within exon 2 of 10 total exons. The mutation results in a leucine to valine substitution at position 12 (L12V) in the IRF1 protein.