ABCC8 encodes the SUR1 subunit of the β‐cell ATP‐sensitive potassium channel whose loss of function causes congenital hyperinsulinism (CHI). Molecular diagnosis is critical for optimal management of CHI patients. Unfortunately, assessing the impact of ABCC8 variants on RNA splicing remains very challenging as this gene is poorly expressed in leukocytes. Here, we performed bioinformatics analysis and cell‐based minigene assays to assess the impact on splicing of 13 ABCC8 variants identified in 20 CHI patients. Next, channel properties of SUR1 proteins expected to originate from minigene‐detected in‐frame splicing defects were analyzed after ectopic expression in COSm6 cells. Out of the analyzed variants, seven induced out‐of‐frame splicing defects and were therefore classified as recessive pathogenic, whereas two led to skipping of in‐frame exons. Channel functional analysis of the latter demonstrated their pathogenicity. Interestingly, the common rs757110 SNP increased exon skipping in our system suggesting that it may act as a disease modifier factor. Our strategy allowed determining the pathogenicity of all selected ABCC8 variants, and CHI‐inheritance pattern for 16 out of the 20 patients. This study highlights the value of combining RNA and protein functional approaches in variant interpretation and reveals the minigene splicing assay as a new tool for CHI molecular diagnostics.

中文翻译：

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基于生物信息学预测、剪接分析和蛋白质分析的未知意义的 ABCC8 变体的功能表征：对准确诊断先天性高胰岛素血症的益处

ABCC8编码 β 细胞 ATP 敏感性钾通道的 SUR1 亚基，其功能丧失导致先天性高胰岛素血症 (CHI)。分子诊断对于 CHI 患者的最佳管理至关重要。不幸的是，评估ABCC8变体对 RNA 剪接的影响仍然非常具有挑战性，因为该基因在白细胞中表达不佳。在这里，我们进行了生物信息学分析和基于细胞的小基因分析，以评估对 13 ABCC8剪接的影响在 20 名 CHI 患者中发现的变异。接下来，在 COSm6 细胞异位表达后，分析了预期源自小基因检测到的框内剪接缺陷的 SUR1 蛋白的通道特性。在分析的变体中，7 个引起框外剪接缺陷，因此被归类为隐性致病，而两个导致框内外显子跳跃。后者的通道功能分析证明了它们的致病性。有趣的是，常见的 rs757110 SNP 增加了我们系统中的外显子跳跃，表明它可能充当疾病调节因子。我们的策略允许确定所有选定的ABCC8的致病性20 名患者中有 16 名的变异和 CHI 遗传模式。本研究强调了在变异解释中结合 RNA 和蛋白质功能方法的价值，并揭示了小基因剪接测定作为 CHI 分子诊断的新工具。