应用Minigene剪接变异体分析技术诊断PMM2基因非经典剪接位点新变异的致病性  

Application of minigene splicing variant analysis to diagnose the pathogenicity of a novel non-canonical splicing-site variant of the PMM2 gene

作　　者：周琴 林伟霞[1] 宋元宗[1] ZHOU Qin;LIN Weixia;SONG Yuanzong(Department of Pediatrics,the First Affiliated Hospital,Jinan University,Guangzhou 510630,Guangdong,China)

机构地区：[1]暨南大学附属第一医院儿科,广东广州510630

出　　处：《暨南大学学报（自然科学与医学版）》2024年第2期124-131,共8页Journal of Jinan University(Natural Science & Medicine Edition)

基　　金：广东省基础与应用基础研究基金项目(2021A1515111083);广州市科技计划项目(202201020088;2023A03J1010);暨南大学附属第一医院临床前沿新技术立项项目(JNU1AF-CFTP2022-a01228)。

摘　　要：目的:研究Minigene剪接变异体分析技术在诊断磷酸甘露糖变位酶2(PMM2)相关先天性糖基化障碍(PMM2-CDG)中的价值,探讨磷酸甘露糖变位酶2(PMM2)基因剪接位点新变异对其转录产物的影响。方法:通过对1例PMM2-CDG患儿进行高通量测序查找可能的遗传学病因,利用Minigene剪接变异体分析技术,研究PMM2基因新剪接位点变异的致病性。根据美国医学遗传学与基因组学学会(ACMG)指南,判断新变异的致病性。结果:遗传学分析发现患儿系PMM2基因母源性c.691G>A(p.Val231Met)变异和父源性c.447+5G>A变异复合杂合子。Minigene剪接变异体分析发现:变异c.447+5G>A导致PMM2基因转录产物形成r.348_447del转录本,为致病性PMM2基因变异。患儿的临床特征为皮肤巩膜黄染,血清总胆红素、非结合胆红素和总胆汁酸明显升高,白蛋白明显降低,甲胎蛋白、铁蛋白和促甲状腺素等升高,对症支持治疗效果欠佳。结论:Minigene剪接变异体分析可为PMM2-CDG确诊和家系遗传咨询提供新的分子标记物,扩展了PMM2基因变异谱,为该病的临床诊治提供新的参考依据。Objective:To investigate the value of minigene splicing variant analysis in the diagnosis of phosphomannomutase 2-congenital disorder of glycosylation(PMM2-CDG),and to explore the impact of a novel splicing-site variant on the transcript products of the PMM2 gene.Methods:High-throughput sequencing was performed on a PMM2-CDG patient to identify the genetic etiology.Minigene splicing variant analysis was performed to explore the pathogenicity of a novel splicing-site variant in the PMM2 gene.According to the guidelines of the American College of Medical Genetics and Genomics(ACMG),the pathogenicity of the novel variant was determined.Results:On genetic analysis,the patient was a compound heterozygote of the maternal c.691G>A(p.Val231Met)and the paternal c.447+5G>A variants of the PMM2 gene.On minigene splicing variant analysis,the c.447+5G>A variant resulted in the formation of the aberrant transcript r.348_447del,indicating a pathogenic PMM2 variant.The clinical features of the patient were jaundice of the skin and sclera.The serum total bilirubin,unconjugated bilirubin,and total bile acids were significantly increased,albumin was significantly decreased,while alpha-fetoprotein,ferritin and thyrotropin were elevated.Symptomatic and supportive therapy was given,but the effect was not promising.Conclusion:Minigene splicing variant analysis revealed a new molecular marker for the definitive diagnosis and familial genetic counseling of PMM2-CDG,expanded the PMM2 genetic variant spectrum,and provided laboratory evidences for the clinical diagnosis and treatment of this condition.

关 键 词：磷酸甘露糖变位酶2(PMM2)基因 PMM2相关先天性糖基化障碍(PMM2-CDG) Minigene剪接变异体分析 

分 类 号：R722.11[医药卫生—儿科]