A G to A substitution is located at the CAG splice donor site of exon 67/intron 67. Two mutant transcripts are produced; one containing all of intron 67, exon 68, 8 bp of intron 68 and exon 69 and the other containing 164 bp of intron 67 and exons 68 and 69. In the first transcript a termination codon is located within intron 67. In the second transcript a termination codon is located at the beginning of exon 68. Expression of these transcripts is seen in the inner ear; however, western blot analysis failed to detect multiple protein isoforms in homozygous mice.