Audiovestibular findings in a branchio-oto syndrome patient with a SIX1 mutation

Abstract

Conclusion: A reported mutation in SIX1 was identified in a patient with familial hearing loss (HL), a left preauricular pit, and bilateral enlarged vestibular aqueducts (EVA). Although the characteristic symptoms of EVA including fluctuating HL and repetitive vertigo were not seen in the patient, further studies are needed to clarify the association between EVA and such symptoms. Objectives: To study the audiovestibular functions, and to identify the causative gene in a patient with branchio-oto syndrome. Methods: We enrolled a 30-year-old female in whom HL was pointed out at the age of 6 years. She visited our department at the age of 21 years, and had not experienced any progression of her HL, tinnitus, or vertigo. Pure-tone audiograms showed bilateral moderate mixed HL with no apparent progression during a 9-year follow-up period. Audiovestibular examinations included distortion product otoacoustic emissions (DPOAEs), electrocochleography (ECochG), and electronystagmography (ENG). Direct sequencing was utilized to screen for SIX1, EYA1, SLC26A4, GJB2, and mitochondrial DNA MTRNR1 including 1555 position. Results: The findings of DPOAEs, ECochG, and ENG indicated cochlear HL with no vestibular dysfunction. A previously reported mutation of a heterozygous c.386A > G (p.Y129C) in SIX1 was detected. No mutation was identified in EYA1, SLC26A4, GJB2, or MTRNR1.

Keywords::

• Hearing loss
• deafness
• vertigo
• enlarged vestibular aqueduct
• distortion-product otoacoustic emissions
• electrocochleography
• electronystagmography

Acknowledgments

We thank the patient who participated in this study. The study was supported in part by Grants-in-Aid for Scientific Research (nos 19591960, 15790924, 14370539, 16659462, 16012215) from the Ministry of Health, Labour and Welfare of Japan, and by Health and Labour Sciences Research Grants (H13-006; Researches on Sensory and Communicative Disorders, and H14-21 and no. 17242101; Research on Measures for Intractable Diseases) from the Ministry of Health, Labour and Welfare of Japan.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.