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目的:对1个Alagille综合征家系进行n JAG1基因变异和临床表型分析，探讨基因型与表型的关系。n 方法:对先证者进行靶向捕获二代测序，并在家系内进行Sanger测序验证。检出的候选致病基因与已知疾病数据库比对并进行致病性评估。分析表型变化特点及基因型与表型的关系。结果:先证者及其姐姐、母亲n JAG1基因均存在c.1270dupG(p.Ala424Glyfs*5)杂合变异，该变异可导致蛋白翻译提前终止，生成未成熟的截短蛋白，可能影响其功能。该变异未见相关文献及数据库报道。先证者表型(胆汁淤积、肺动脉狭窄和特殊面容)与姐姐(胆汁淤积伴瘙痒、角膜后胚胎环)、母亲(无临床表现)各不相同，且胆汁淤积、特殊面容随年龄增长不再明显。n 结论:JAG1基因c．1270dupG(p.Ala424Glyfs*5)变异可导致不同表型的Alagille综合征，亦存在表型不完全外显现象。n “,”Objective:To explore the genetic basis of a pedigree affected with Alagille syndrome (ALGS).Methods:Targeted capture and next generation sequencing was carried out for the proband. Candidate variants were verified by Sanger sequencing among his family members. Their pathogenicity of the variant was predicted with bioinformatic analysis. Clinical characteristics and genotype-phenotype correlation were analyzed.Results:The proband, his elder sister and mother were found to carry a heterozygous c. 1270dupG (p.Ala424Glyfs*5) variant of the n JAG1 gene, which may lead to premature termination of translation and a truncated protein with loss of function. The variant was unreported previously. The phenotypes of the proband (cholestasis, pulmonary artery stenosis and peculiar faces) have differed from those of his elder sister (cholestasis with pruritus, posterior embryonic ring of cornea) and mother (with no clinical manifestation). Cholestasis and peculiar face of the proband became insignificant with age.n Conclusion:The c. 1270dupG (p.Ala424Glyfs*5) variant of the n JAG1 gene probably underlay the ALGS in this pedigree with incomplete penetrance.n