목적: Mutation in SLC26A4 (PDS), which encodes pendrin, is a common cause of genetic hearing loss, especially among newborns in East Asia, where PDS mutation is common cause of congenital hearing loss. The hearing phenotype in patients with a PDS mutation is quite different from that in this mouse model. Many patients with PDS mutation have significant residual hearing, in some cases until early childhood. However, the level of hearing in these patients at birth and the time of progression of hearing loss have not been studied. 방법:We reviewed the medical records for 102 patients with pendrin mutation between September 2003 and December 2014. Among them, newborn hearing screening test had been performed on 24. We reviewed the medical records for patients 1) who were diagnosed with pendrin mutation before 3 years old, and 2) who performed hearing tests more than twice by same methods (ASSR/ABR). We analyzed the hearing levels in these patients by age. 결과:Among 24 patients with pendrin mutation who performed newborn hearing screening tests, eight (33.3%) passed newborn hearing screening test in both ears and six (25.0%) passed in one ear. Among 14 patients with pendrin mutation who performed hearing tests more than twice under 3 years old, the hearing levels of twelve (85.7%) patients deteriorated rapidly before 3 years old. Among 18 patients with pendrin mutation who performed hearing tests more than twice from 3 years old to 10 years old, the hearing levels of 3 (16.7%) patients deteriorated and the hearing levels of most patients were relatively stable. 결론:These data suggest that patients with pendrin mutation have significant residual hearing at birth. And the deterioration of hearing level in patients with pendrin mutation occurs within 3 years old. After 3 years old, the residual hearings were relatively stable and did not tend to deteriorate. Therefore, in the patients with pendrin mutation, early intervention to preserve residual hearing should be a clinical focus.