Chen Anhai, Ling Jie, Peng Xin, Liu Xianlin, Mao Shuang, Chen Yongjia, Qin Mengyao, Zhang Shuai, Bai Yijiang, Song Jian, Feng Zhili, Ma Lu, He Dinghua, Mei Lingyun, He Chufeng, Feng Yong
Department of Otorhinolaryngology, Xiangya Hospital, Central South University, Changsha, China.
Key Laboratory of Otolaryngology Major Disease Research of Hunan Province, Changsha, China.
Clin Exp Otorhinolaryngol. 2023 Nov;16(4):342-358. doi: 10.21053/ceo.2023.00668. Epub 2023 Oct 11.
Branchio-oto syndrome (BOS) primarily manifests as hearing loss, preauricular pits, and branchial defects. EYA1 is the most common pathogenic gene, and splicing mutations account for a substantial proportion of cases. However, few studies have addressed the structural changes in the protein caused by splicing mutations and potential pathogenic factors, and several studies have shown that middle-ear surgery has limited effectiveness in improving hearing in these patients. BOS has also been relatively infrequently reported in the Chinese population. This study explored the genetic etiology in the family of a proband with BOS and provided clinical treatment to improve the patient's hearing.
We collected detailed clinical features and peripheral blood samples from the patients and unaffected individuals within the family. Pathogenic mutations were identified by whole-exome sequencing and cosegregation analysis and classified according to the American College of Medical Genetics and Genomics guidelines. Alternative splicing was verified through a minigene assay. The predicted three-dimensional protein structure and biochemical experiments were used to investigate the pathogenicity of the mutation. The proband underwent middle-ear surgery and was followed up at 1 month and 6 months postoperatively to monitor auditory improvement.
A novel heterozygous EYA1 splicing variant (c.1050+4 A>C) was identified and classified as pathogenic (PVS1(RNA), PM2, PP1). Skipping of exon 11 of the EYA1 pre-mRNA was confirmed using a minigene assay. This mutation may impair EYA1-SIX1 interactions, as shown by an immunoprecipitation assay. The EYA1-Mut protein exhibited cellular mislocalization and decreased protein expression in cytological experiments. Middle-ear surgery significantly improved hearing loss caused by bone-conduction abnormalities in the proband.
We reported a novel splicing variant of EYA1 in a Chinese family with BOS and revealed the potential molecular pathogenic mechanism. The significant hearing improvement observed in the proband after middle-ear surgery provides a reference for auditory rehabilitation in similar patients.
鳃耳综合征（BOS）主要表现为听力丧失、耳前凹和鳃裂缺陷。EYA1是最常见的致病基因，剪接突变占相当一部分病例。然而，很少有研究探讨剪接突变导致的蛋白质结构变化和潜在致病因素，并且多项研究表明中耳手术在改善这些患者听力方面效果有限。BOS在中国人群中的报道也相对较少。本研究探讨了一名BOS先证者家族中的遗传病因，并提供临床治疗以改善患者听力。
我们收集了患者及其家族中未患病个体的详细临床特征和外周血样本。通过全外显子组测序和共分离分析鉴定致病突变，并根据美国医学遗传学与基因组学学会指南进行分类。通过小基因检测验证可变剪接。利用预测的三维蛋白质结构和生化实验研究突变的致病性。先证者接受了中耳手术，并在术后1个月和6个月进行随访以监测听力改善情况。
鉴定出一种新的杂合EYA1剪接变异体（c.1050+4 A>C），并分类为致病（PVS1[RNA]，PM2，PP1）。使用小基因检测证实了EYA1前体mRNA外显子11的跳跃。免疫沉淀试验表明，该突变可能损害EYA1-SIX1相互作用。在细胞学实验中，EYA1-Mut蛋白表现出细胞定位错误和蛋白表达降低。中耳手术显著改善了先证者由骨导异常引起的听力损失。
我们报道了一个中国BOS家族中的新型EYA1剪接变异体，并揭示了潜在的分子致病机制。先证者中耳手术后观察到的显著听力改善为类似患者的听觉康复提供了参考。
