TNN is first linked to auditory neuropathy

Autosomal recessive nonsyndromic auditory neuropathy is attributed to a genetic etiology. We identified a compound heterozygous missense variant, c.G736A (p.G246S) and c.C2954T (p.T985 M) in TNN of affected patients in a pedigree via candidate gene screening and exome sequencing. To determine the genetic etiology of deafness in the pedigree with a heterozygous missense variant in the gene TNN encoding tenascin-W associated with autosomal recessive nonsyndromic auditory neuropathy, the cochlear expression of tenascin-W was evaluated at mRNA and protein levels in mice, and Tnn knock out mice were generated and utilized to study the function of Tnn in the auditory system. Immunofluorescence stainings showed that tenascin-W was mainly expressed in the somatic cytoplasm of spiral ganglion neurons of mice. Homozygous Tnn knockout was lethal in mice, whereas Tnn heterozygous mice showed decreases in spiral ganglion neuron density and progressive hearing loss. We demonstrate that tenascin-W is expressed in the murine cochleae and is essential for the development of spiral ganglion neurons. An abnormal expression of tenascin-W can influence the development and function of SGNs and affect the function of the auditory system.