ENU mutagenesis induced a T to A transversion at base pair 66,833,880 (v38) on chromosome 4, or base pair 6,070 in the GenBank genomic region NC_000070. The mutation lies in the splice acceptor site of intron 1 of the 3 exon gene, and affects a thymine base 14 nucleotides from the next exon. One possibility, shown below, is that aberrant splicing may result in skipping of the 167 bp exon 2, utilization of the acceptor splice site from intron 2, and splicing of exon 1 to exon 3. Deletion of exon 2 would result in a frame-shift and the coding of one aberrant amino acid followed by a premature stop codon (the second abnormal codon after exon 1).