GJB2 and Hearing impairment: Further transiently transfection experiments demonstrated that the R187C and R187H mutations do not affect the subcellular localization of the gene product in vitro, while the H783Y mutation emerged in a worm-eaten pattern, suggesting the potential involvement of hearing impairment.[7] However, based on the large-scale screening, in Japanese patients, the primary causes of hearing loss are mutations in gap junction protein beta 2 (GJB2), solute carrier family 26 member 4 (SLC26A4), cadherin-related 23 (CDH23), and mitochondrial DNA 1555A→G mutation.