Otoferlin is a protein that in humans is encoded by the OTOF gene. Mutations in this gene are a cause of neurosensory nonsyndromic recessive deafness, DFNB9. The short form of the encoded protein has three C2 domains, a single carboxy-terminal transmembrane domain found also in the C. elegans spermatogenesis factor FER-1 and human dysferlin, while the long form has six C2 domains. The homology suggests that this protein may be involved in vesicle membrane fusion. Several transcript variants encoding multipleisoforms have been found for this gene.