Oh Seak Hee, Sung Young Hoon, Kim Inki, Sim Chan Kyu, Lee Jung Hoon, Baek Minkyung, Pack Chan-Gi, Seok Chaok, Seo Eul Ju, Lee Myeong Sup, Kim Kyung Mo
Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea.
Department of Convergence Medicine, Asan Institutes for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Inflamm Bowel Dis. 2019 Feb 21;25(3):498-509. doi: 10.1093/ibd/izy353.
Very early-onset inflammatory bowel disease (VEO-IBD) is often associated with monogenetic disorders. IL-10RA deficiency is one of the major causal mutations in VEO-IBD. Here, we aimed to identify the causal mutation associated with severe IBD in a 1-year-old patient, validate the pathogenicity of the mutation, and characterize the mutant protein.
To identify the causal mutation, targeted exome sequencing (ES) was performed using the genomic DNA from the patient. To validate the pathogenicity, IL-10RA functional tests were performed using the patient's peripheral blood mononuclear cells (PBMCs). Additionally, flow cytometry analysis, confocal microscopy on overexpressed green fluorescent protein-fused mutants, and computational analysis on the structures of IL-10RA proteins were performed.
We identified a novel compound heterozygote mutation p.[Tyr91Cys];[Pro146Alafs40] in the IL10RA gene of the patient. The missense variant p.Tyr91Cys was previously identified but not functionally tested, and a frameshift variant, p.Pro146Alafs40, is novel and nonfunctional. PBMCs from the patient showed defective signal transducer and activator of transcription 3 activation. The p.Tyr91Cys mutant protein failed to properly localize on the plasma membrane. The p.Tyr91Cys mutation seems to disrupt the hydrophobic core structure surrounding the tyrosine 91 residue, causing structural instability.
Targeted ES and linkage analysis identified novel compound heterozygous mutations p.[Tyr91Cys];[Pro146Alafs*40] in the IL10RA gene of a child with severe VEO-IBD. p.Tyr91Cys proteins were functionally defective in IL-10RA signaling and failed to properly localize on the plasma membrane, probably due to its structural instability.
极早发型炎症性肠病（VEO-IBD）常与单基因疾病相关。白细胞介素10受体α亚基（IL-10RA）缺陷是VEO-IBD的主要致病突变之一。在此，我们旨在鉴定一名1岁患者中与重度炎症性肠病相关的致病突变，验证该突变的致病性，并对突变蛋白进行表征。
为鉴定致病突变，使用患者的基因组DNA进行靶向外显子组测序（ES）。为验证致病性，使用患者的外周血单个核细胞（PBMC）进行IL-10RA功能测试。此外，还进行了流式细胞术分析、对过表达绿色荧光蛋白融合突变体的共聚焦显微镜检查以及对IL-10RA蛋白结构的计算分析。
我们在患者的IL10RA基因中鉴定出一种新的复合杂合突变p.[Tyr91Cys]；[Pro146Alafs40]。错义变体p.Tyr91Cys先前已被鉴定但未进行功能测试，而移码变体p.Pro146Alafs40是新的且无功能。患者的PBMC显示信号转导子和转录激活子3激活存在缺陷。p.Tyr91Cys突变蛋白未能正确定位于质膜上。p.Tyr91Cys突变似乎破坏了围绕酪氨酸91残基的疏水核心结构，导致结构不稳定。
靶向ES和连锁分析在一名重度VEO-IBD儿童的IL10RA基因中鉴定出新型复合杂合突变p.[Tyr91Cys]；[Pro146Alafs*40]。p.Tyr91Cys蛋白在IL-10RA信号传导中功能缺陷，且可能由于其结构不稳定而未能正确定位于质膜上。
