title: Identities and frequencies of mutations of the otoferlin gene (OTOF) causing DFNB9 deafness in Pakistan.
abstract: Mutations in OTOF, encoding otoferlin, cause non-syndromic recessive hearing loss. The goal of our study was to define the identities and frequencies of OTOF mutations in a model population. We screened a cohort of 557 large consanguineous Pakistani families segregating recessive, severe-to-profound, prelingual-onset deafness for linkage to DFNB9. There were 13 families segregating deafness consistent with linkage to markers for DFNB9. We analyzed the genomic nucleotide sequence of OTOF and detected probable pathogenic sequence variants among all 13 families. These include the previously reported nonsense mutation p.R708X and 10 novel variants: 3 nonsense mutations (p.R425X, p.W536X, and p.Y1603X), 1 frameshift (c.1103_1104delinsC), 1 single amino acid deletion (p.E766del) and 5 missense substitutions of conserved residues (p.L573R, p.A1090E, p.E1733K, p.R1856Q and p.R1939W). OTOF mutations thus account for deafness in 13 (2.3%) of 557 Pakistani families. This overall prevalence is similar, but the mutation spectrum is different from those for Western populations. In addition, we demonstrate the existence of an alternative splice isoform of OTOF expressed in the human cochlea. This isoform must be required for human hearing because it encodes a unique alternative C-terminus affected by some DFNB9 mutations.
authors.affiliation: Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD 20850, USA.
authors.forename: B Y
authors.initials: BY
authors.lastname: Choi
authors.forename: Z M
authors.initials: ZM
authors.lastname: Ahmed
authors.forename: S
authors.initials: S
authors.lastname: Riazuddin
authors.forename: M A
authors.initials: MA
authors.lastname: Bhinder
authors.forename: M
authors.initials: M
authors.lastname: Shahzad
authors.forename: T
authors.initials: T
authors.lastname: Husnain
authors.forename: S
authors.initials: S
authors.lastname: Riazuddin
authors.forename: A J
authors.initials: AJ
authors.lastname: Griffith
authors.forename: T B
authors.initials: TB
authors.lastname: Friedman
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D003051:Cochlea / Q000378:metabolism; D003638:Deafness / Q000235:genetics*; D005091:Exons; D005787:Gene Frequency / Q000235:genetics*; D005808:Genes, Recessive; D014644:Genetic Variation; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010154:Pakistan; D010375:Pedigree; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; C118457:OTOF protein, human; D020033:Protein Isoforms