Residual Hearing in DFNB1 Deafness and Its Clinical Implication in a Korean Population

So Young Kim; Ah Reum Kim; Kyu Hee Han; Min Young Kim; Eun-Hee Jeon; Ja-Won Koo; Seung Ha Oh; Byung Yoon Choi

doi:10.1371/journal.pone.0125416

Residual Hearing in DFNB1 Deafness and Its Clinical Implication in a Korean Population

PLoS One. 2015 Jun 10;10(6):e0125416. doi: 10.1371/journal.pone.0125416. eCollection 2015.

Authors

So Young Kim¹, Ah Reum Kim¹, Kyu Hee Han², Min Young Kim³, Eun-Hee Jeon³, Ja-Won Koo⁴, Seung Ha Oh⁵, Byung Yoon Choi⁴

Affiliations

¹ Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
² Department of Otorhinolaryngology-Head and Neck Surgery, National Medical Center, Seoul, Korea.
³ Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
⁴ Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea; Sensory Organ Research Institute, Seoul National University Medical Research Center, Seoul, Korea.
⁵ Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea; Sensory Organ Research Institute, Seoul National University Medical Research Center, Seoul, Korea.

Abstract

Introduction: The contribution of Gap junction beta-2 protein (GJB2) to the genetic load of deafness and its mutation spectra vary among different ethnic groups.

Objective: In this study, the mutation spectrum and audiologic features of patients with GJB2 mutations were evaluated with a specific focus on residual hearing.

Methods: An initial cohort of 588 subjects from 304 families with varying degrees of hearing loss were collected at the otolaryngology clinics of Seoul National University Hospital and Seoul National University Bundang Hospital from September 2010 through January 2014. GJB2 sequencing was carried out for 130 probands with sporadic or autosomal recessive non syndromic hearing loss. The audiograms were evaluated in the GJB2 mutants.

Results: Of the 130 subjects, 22 (16.9%) were found to carry at least one mutant allele of GJB2. The c.235delC mutation was shown to have the most common allele frequency (39.0%) among GJB2 mutations, followed by p.R143W (26.8%) and p.V37I (9.8%). Among those probands without the p.V37I allele in a trans configuration who showed some degree of residual hearing, the mean air conduction thresholds at 250 and 500 Hz were 57 dB HL and 77.8 dB HL, respectively. The c.235delC mutation showed a particularly wide spectrum of hearing loss, from mild to profound and significantly better hearing thresholds at 250 Hz and 2k Hz than in the non-p.V37I and non-235delC nonsyndromic hearing loss and deafness 1(DFNB1) subjects.

Conclusion: Despite its reputation as the cause of severe to profound deafness, c.235delC, the most frequent DFNB1 mutation in our cohort, caused a wide range of hearing loss with some residual hearing in low frequencies. This finding can be of paramount help for prediction of low frequency hearing thresholds in very young DFNB1 patients and highlights the importance of soft surgery for cochlear implantation in these patients.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Cohort Studies
Connexin 26
Connexins / genetics*
Deafness / genetics*
Deafness / physiopathology*
Humans
Mutation
Republic of Korea

Substances

Connexins
GJB2 protein, human
Connexin 26

Grants and funding

This study was supported by the Korean Healthcare Technology R&D Project, Ministry for Health, Welfare, and Family Affairs, Republic of Korea (HI14C1867), and the Seoul National University Bundang Hospital Research Fund (06-2011-024 to B.-Y. Choi). The funding bodies had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.