The mutation has been identified as a T to A transversion at nucleotide position 3002 of the genomic DNA sequence (GenBank accession NC_000086.6, NCBI Build 37.1). It lies in the splice acceptor site of the third intron. The affected thymine resides five nucleotides from the next exon, the fourth of the gene's seven exons. cDNA sequence analysis revealed that the mutation results in skipping of exon 4, a frameshift, and and premature termination of translation after amino acid 88 of the normally 236 amino acid protein.