GJB2 and deafness: Although some mutational hotspots involved in inherited hearing impairment, such as GJB2 235 delC, SLC26A4 IVS7-2A>G, and mitochondrial DNA 1555A>G, have been reported in Chinese deaf populations, the molecular etiology of deafness in Chinese children has not been investigated systematically, and effective genetic evaluation strategies for hearing impairment are not available in most areas of China.