Investigation of the hearing levels of siblings affected by a single GJB2 variant: Possibility of genetic modifiers. (October 2021)

• Record Type: Journal Article
• Authors: Hosoya, Makoto; Fujioka, Masato; Nara, Kiyomitsu; Morimoto, Noriko; Masuda, Sawako; Sugiuchi, Tomoko; Katsunuma, Sayaka; Takagi, Akira; Morita, Noriko; Ogawa, Kaoru; Kaga, Kimitaka; Matsunaga, Tatsuo
• Is Part Of: International journal of pediatric otorhinolaryngology. Volume 149(2021)
• Publication Date: 2021-10
• Subjects: Hereditary hearing loss -- GJB2 -- Connexin 26 -- Sibling -- Hearing level -- Genetic modifier; Otolaryngology -- Periodicals; Pediatrics -- Periodicals; Otolaryngology -- Periodicals; Pediatrics -- Periodicals; Oto-rhino-laryngologie -- Périodiques; Pédiatrie -- Périodiques; 618.9209751
• DOI: 10.1016/j.ijporl.2021.110840
• Languages: English
• ISSNs: 0165-5876

Abstract

Abstract: Objective: Variants in GJB2 can cause autosomal recessive deafness (DFNB1). There is evidence for genotype–phenotype correlations of GJB2 variants; however, several genotypes can cause varying levels of hearing loss likely attributable to differences in genetic or environmental background. As siblings share approximately 50% of their genetic background and usually have a common environmental background, analysis of phenotypes of siblings with a specific GJB2 variant may reveal factors relevant to phenotypic variation. There have been no previous analyses of differences in hearing among siblings carrying a single GJB2 genotype. Here, we investigated hearing differences between siblings with a single GJB2 variant, which can cause various levels of hearing loss. Methods: We examined hearing levels in 16 pairs of siblings homozygous for the c.235delC variant of GJB2 . Differences in hearing acuity between sibling pairs were detected by auditory evaluation. Results: Average differences in acoustic threshold >30 dB were observed between five pairs of siblings, whereas the remaining 11 pairs had average threshold values within approximately 10 dB of one another. Hearing loss varied from moderate to profound. Conclusion: Our results indicate that auditory acuity associated with homozygosity for GJB2 c.235delC can vary in degree; however, in approximately 70% of younger siblings, it was approximately the same as that in the first child, despite a diverse spectrum of hearing loss among different families. These results suggest that differences in genetic background may modify the phenotype associated with homozygous GJB2 c.235delC. Highlights: Hearing levels in 16 pairs of siblings homozygous for c.235delC variant of GJB2 were investigated. In about 70% of younger siblings, hearing level was approximately the same as that in the first child. The genetic background of recessive deaf patients with homozygous GJB2 c.235delC variant may affect severity of deafness. Possibility of genetic modifiers for hearing loss caused by GJB2 variant was suggested.