T to A transversion at base pair 71,685,545 (v38) on chromosome 8, or base pair 9,163 in the GenBank genomic region NC_000074 encoding Jak3. The mutation corresponds to residue 2,849 in the mRNA sequence NM_010589 within exon 19 of 25 total exons, and to residue 2,849 in the mRNA sequence NM_001190830 within exon 19 of 24 total exons. he mutation results in a valine (V) to aspartic acid (D) substitution at position 880 (V880D) in the JAK3 protein. (J:274939)