and found to be incomplete for the OTOF locus, so more markers were purchased. During this time, a fourth NSRAN family was obtained, so all four families were genotyped using the five dinucleotide markers from the OTOF locus, D2S2221, D2S2144, D2S165, D2S365, and D2S2347. Haplotype analysis was consistent with linkage for all four families (fig 1). The otoferlin gene ( OTOF ) was noted to be located between markers D2S2144 and D2S165. 22 Two point linkage analysis gave a maximum lod score of 2.908 for the four families at marker D2S2144 and a multipoint analysis produced a maximum lod score of 3.47. NSRAN mutations in OTOF All of the known OTOF exons and approximately 100 bases of the introns flanking these exons from each of the proband's DNA from the four families was sequenced and examined for mutations. All mutations are identified by their position in GenBank file AF183185. Once a mutation was identified, DNA from the rest of the family was sequenced to determine mutation segregation. A control sample of 94 normal hearing, unrelated persons was tested using restriction enzyme digestion. The results are summarised in table 4. In family 1802, the affected subjects were observed to be compound heterozygous for a frameshift mutation and a missense mutation. The frameshift mutation is the result of deletion of a guanine at position 1778 (exon 16), which causes a stop codon after four additional amino acids. The missense mutation, 6141G&gt;A, substitutes a glutamine for an arginine at the second codon in