Research progress in pathogenic genes of hereditary non-syndromic mid-frequency deafness

Hearing impairment is considered as the most prevalent impairment worldwide. Almost 600 million people in the world suffer from mild or moderate hearing impairment, an estimated 10% of the human population. Genetic factors play an important role in the pathogenesis of this disorder. Hereditary hearing loss is divided into syndromic hearing loss (associated with other anomalies) and non-syndromic hearing loss (not associated with other anomalies). Approximately 80% of genetic deafness is non-syndromic. On the basis of the frequency of hearing loss, hereditary non-syndromic hearing loss can be divided into high-, mid-, low-, and total-frequency hearing loss. An audiometric finding of mid-frequency sensorineural hearing loss, or a "bowl-shaped" audiogram, is uncommon. Up to now, merely 7 loci have been linked to mid-frequency hearing loss. Only four genetic midfrequency deafness genes, namely, DFNA10 (EYA4), DFNA8/12 (TECTA), DFNA13 (COL11A2), DFNA44 (CCDC50), have been reported to date. This review summarizes the research progress of the four genes to draw attention to mid-frequency deafness genes.