Supplementary Material for: Whole-Exome Sequencing Targeting a Gene Panel for Sensorineural Hearing Loss: The First Portuguese Cohort Study

Next-generation sequencing (NGS) technologies revolutionized the molecular diagnosis of sensorineural hearing loss (SNHL) and are now a standard of care. In this study, 71 Portuguese probands with hereditary SNHL were assessed by whole-exome sequencing (WES) targeting a panel of 158 genes related to SNHL, aiming to evaluate the diagnostic yield of this methodological approach and to report the spectrum of variants. Patients with either nonsyndromic or syndromic SNHL were included. Also, patients were previously screened for variants in the <i>GJB2</i> gene and for duplications/deletions in the <i>GJB6</i> gene. Causative variants in 11 different genes were identified in 15 (21.1%) out of 71 probands, 5 of which had associated syndromes. In 6 other patients (8.5%), presumptive causative variants were identified in <i>MYO15A</i>, <i>TMIE</i>, <i>TBC1D24</i>, <i>SPMX</i>, <i>GJB3</i>, <i>PCDH15</i>, and <i>CDH23</i> genes, uncovering a potential case of digenic Usher syndrome. The study was inconclusive in 20 probands (28.2%), in 19 due to lack of segregation analysis and in one due to uncertain phenotype-genotype matching. In the remaining 30 patients (42.3%) no potentially causative variants were identified. The diagnostic yield did not significantly vary according to the age of hearing-impairment onset. As the first study on the application of NGS technologies in SNHL based on a Portuguese cohort, our results may contribute to characterize the spectrum of variants related to SNHL in the Portuguese population. Additionally, the present study provides new insights into the contribution of <i>MYO3A</i>, <i>TECTA</i>, <i>EDNRB</i>, <i>TBC1D24</i>, and <i>GJB3</i> genes to SNHL. For the significant number of undiagnosed patients, reanalysis of WES data – either for a broader gene panel or in a non-targeted approach – may be considered.

下一代测序（Next-generation sequencing, NGS）技术彻底革新了感音神经性听力损失（sensorineural hearing loss, SNHL）的分子诊断，现已成为临床标准诊疗方案。本研究针对158个与感音神经性听力损失相关的基因构建靶向测序基因panel，对71名葡萄牙籍遗传性感音神经性听力损失先证者开展全外显子组测序（whole-exome sequencing, WES），旨在评估该检测方法的诊断检出率并系统报道致病变异的频谱特征。研究纳入非综合征型或综合征型感音神经性听力损失患者，所有受试者此前均已完成GJB2基因变异筛查以及GJB6基因的重复/缺失拷贝数变异检测。
最终在71名先证者中的15名（21.1%）体内鉴定出11个不同基因的致病变异，其中5名患者伴随综合征表型。另有6名患者（8.5%）在MYO15A、TMIE、TBC1D24、SPMX、GJB3、PCDH15及CDH23基因中检出疑似致病变异，其中发现1例潜在的双基因致病型乌谢尔综合征（Usher syndrome）。
本研究在20名先证者（28.2%）中未得出明确诊断结论，其中19例因缺乏分离分析数据，1例因表型与基因型匹配关系不明确。剩余30名患者（42.3%）未检出任何潜在致病变异。诊断检出率未随听力损失发病年龄呈现显著差异。
作为首个基于葡萄牙人群队列开展的NGS技术应用于感音神经性听力损失的研究，本研究结果可为明确葡萄牙人群中感音神经性听力损失相关变异的频谱分布提供参考。此外，本研究还为MYO3A、TECTA、EDNRB、TBC1D24及GJB3基因在感音神经性听力损失中的致病贡献提供了新的研究视角。针对占比较高的未确诊患者，可考虑对全外显子组测序数据进行重新分析——可采用覆盖范围更广的基因panel或非靶向测序策略。