title: Identification of 17 hearing impaired mouse strains in the TMGC ENU-mutagenesis screen.
abstract: The Tennessee Mouse Genome Consortium (TMGC) employed an N-ethyl-N-nitrosourea (ENU)-mutagenesis scheme to identify mouse recessive mutants with hearing phenotypes. We employed auditory brainstem responses (ABR) to click and 8, 16, and 32 kHz stimuli and screened 285 pedigrees (1819 mice of 8-11 weeks old in various mixed genetic backgrounds) each bred to carry a homozygous ENU-induced mutation. To define mutant pedigrees, we measured > or = 12 mice per pedigree in > or = 2 generations and used a criterion where the mean ABR threshold per pedigree was two standard deviations above the mean of all offspring from the same parental strain. We thus identified 17 mutant pedigrees (6%), all exhibiting hearing loss at high frequencies (> or = 16 kHz) with an average threshold elevation of 30-35 dB SPL. Interestingly, four mutants showed sex-biased hearing loss and six mutants displayed wide range frequency hearing loss. Temporal bone histology revealed that six of the first nine mutants displayed cochlear morphological defects: degeneration of spiral ganglia, spiral ligament fibrocytes or inner hair cells (but not outer hair cells) mostly in basal turns. In contrast to other ENU-mutagenesis auditory screens, our screen identified high-frequency, mild and sex-biased hearing defects. Further characterization of these 17 mouse models will advance our understanding of presbycusis and noise-induced hearing loss in humans.
authors.affiliation: Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
authors.forename: Mohammad Habiby
authors.initials: MH
authors.lastname: Kermany
authors.forename: Lisan L
authors.initials: LL
authors.lastname: Parker
authors.forename: Yun-Kai
authors.initials: YK
authors.lastname: Guo
authors.forename: Darla
authors.initials: D
authors.lastname: Miller
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Swanson
authors.forename: Tai-June
authors.initials: TJ
authors.lastname: Yoo
authors.forename: Dan
authors.initials: D
authors.lastname: Goldowitz
authors.forename: Jian
authors.initials: J
authors.lastname: Zuo
mesh_terms: D000818:Animals; D003051:Cochlea / Q000473:pathology; D004195:Disease Models, Animal; D005038:Ethylnitrosourea; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005820:Genetic Testing / Q000379:methods; D006317:Hearing Loss, Noise-Induced / Q000175:diagnosis / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D016296:Mutagenesis; D009153:Mutagens; D009622:Noise / Q000009:adverse effects; D010375:Pedigree; D010641:Phenotype; D011304:Presbycusis / Q000175:diagnosis / Q000235:genetics*; D012737:Sex Factors
chemical_list: D009153:Mutagens; D005038:Ethylnitrosourea