ENU mutagenesis induced a T to A transversion at base pair 122,582,449 (v38) on chromosome 7, or base pair 293,370 in the GenBank genomic region NC_000073. The mutation corresponds to residue 1,479 in the mRNA sequence NM_008855 within exon 11 of 17 total exons. The mutation results in a methionine (M) to lysine (K) substitution at position 420 (M420K).