ENU-induced C to T transition at base pair 135,615,349 (v38) on chromosome 3, or base pair 76,634 in the GenBank genomic region NC_000069. The mutation corresponds to residue 1,146 in the mRNA sequence NM_008689 within exon 9 of 25 total exons. The mutation results in a threonine to isoleucine substitution at position 215 (T215I) in the NF-B1 protein. (J:272148)