ENU-induced A to C transversion at base pair 71,683,978 (v38) on chromosome 8, or base pair 7,596 in the GenBank genomic region NC_000074 encoding Jak3. The mutation corresponds to residue 2,138 in the mRNA sequence NM_010589 within exon 15 of 25 total exons. The mutation results in an asparagine to threonine substitution at position 643 (N643T) in the JAK3 protein.