Sun Rongyue, Zhu Ting, Zhou Tingmin, Luo Yanzhao, Jiang Tiantian, Gu Chuangjie, Wu Ruiting, Wang Yue, Xu Fengzhen, Fan Shikang, Wang Dan, Chen Yiming
Department of Pulmonary and Critical Care Medicine, People's Hospital of Jingning She Autonomous County, Lishui, 323000, Zhejiang, P. R. China.
Department of Pediatrics, The First Affiliated Hospital of Wenzhou Medical University, No.2 Fuxue Road, Wenzhou, 325000, Zhejiang, P. R. China.
BMC Med Genomics. 2025 Jul 18;18(1):118. doi: 10.1186/s12920-025-02187-4.
Hyperbilirubinemia is the main clinical manifestation of Dubin-Johnson syndrome (DJS), of which most cases can be attributed to the variants in the ABCC2 gene. This study aimed to characterize the mechanism of a splicing variant of the ABCC2 gene and interrogate the variant pathogenicity.
Whole exome sequencing (WES) was performed to identify potential genetic causes. Bioinformatics analysis was performed to predict the variant pathogenicity. Minigene assays were performed to investigate the effects of the identified variant on mRNA splicing. Western blot (WB) experiments were performed to verify the impact of the variant on protein expression. Protein subcellular localization was analyzed by indirect immunofluorescence (IF).
Genetic analysis revealed compound heterozygous variants in ABCC2 gene: the splice-site variant c.2439 + 5G > A inherited from the mother and the nonsense variant c.3825 C > G (p.Y1275X) inherited from the father. The recurrent ABCC2 c.2439 + 5G > A variant can affect mRNA splicing which leads to the skipping of exon 18 and induces the loss of 56 native amino acids, resulting in a shortened MRP2 protein (p.Gly758_Lys813del). The c.2439 + 5G > A variant may cause mislocalization of the mutant protein and significantly reduces its expression.
Our study identifies c.2439 + 5G > A in ABCC2 as a pathogenic variant underlying DJS through aberrant splicing. Critically, the proband's phenotype resulted from compound heterozygous variants leading to biallelic loss of functional protein. These findings highlight the necessity of comprehensive ABCC2 genetic testing for DJS, facilitating accurate diagnosis and personalized patient management.
高胆红素血症是杜宾-约翰逊综合征（DJS）的主要临床表现，其中大多数病例可归因于ABCC2基因的变异。本研究旨在阐明ABCC2基因剪接变异的机制并探究该变异的致病性。
进行全外显子组测序（WES）以确定潜在的遗传原因。进行生物信息学分析以预测变异的致病性。进行小基因检测以研究已鉴定变异对mRNA剪接的影响。进行蛋白质免疫印迹（WB）实验以验证变异对蛋白质表达的影响。通过间接免疫荧光（IF）分析蛋白质亚细胞定位。
遗传分析揭示了ABCC2基因中的复合杂合变异：从母亲遗传的剪接位点变异c.2439 + 5G > A和从父亲遗传的无义变异c.3825 C > G（p.Y1275X）。复发性ABCC2 c.2439 + 5G > A变异可影响mRNA剪接，导致外显子18跳跃并导致56个天然氨基酸缺失，从而产生缩短的多药耐药相关蛋白2（MRP2）蛋白（p.Gly758_Lys813del）。c.2439 + 5G > A变异可能导致突变蛋白的错误定位并显著降低其表达。
我们的研究通过异常剪接将ABCC2基因中的c.2439 + 5G > A鉴定为DJS的致病变异。至关重要的是，先证者的表型是由复合杂合变异导致双等位基因功能性蛋白缺失所致。这些发现凸显了对DJS进行全面ABCC2基因检测的必要性，有助于准确诊断和个性化的患者管理。
