隐性营养不良型大疱性表皮松解症4例COL7A1基因突变分析

【摘要】 目的 分析4例隐性营养不良型大疱性表皮松解症（RDEB）患儿基因突变与临床表型情况。方法 收集4例RDEB患儿临床资料，提取患儿及其父母外周血DNA，使用先天性大疱性表皮松解症多基因芯片进行高通量测序，确定致病基因位点后，采用Sanger测序法进行双向验证。结果 4例患儿基因检测均显示COL7A1基因复合杂合突变，共8个突变位点。例1为中度泛发型RDEB，存在父源c.7828C>T和母源c.448G>A突变；例2为中度泛发型，存在父源c.3625_3635del和母源 c.2726_2728del突变；例3为局限型，存在父源突变c.682+1G>A和等位基因突变c.5532+1G>A，其父母外周血DNA未发现c.5532+1G>A突变；例4为重度泛发型，存在父源c.5196delC和母源c.500_501insAGGG突变。其中c.2726_2728del和c.5196delC突变既往未见报道。结论 4例RDEB患儿均存在COL7A1基因复合杂合突变，可能为其致病原因。其中，双等位基因移码突变携带者的表型重于双等位基因剪切位点、错义和无义、移码和氨基酸缺失及插入组成的复合杂合突变携带者表型。

Mutation analysis of the COL7A1 gene in 4 cases of recessive dystrophic epidermolysis bullosa

【Abstract】 Objective To analyze gene mutations in and clinical phenotypes of 4 children with recessive dystrophic epidermolysis bullosa （RDEB）. Methods Clinical data were collected from 4 children with RDEB, and DNA was extracted from peripheral blood samples of the children and their parents. A multi-gene panel targeting congenital epidermolysis bullosa was used for high-throughput sequencing. After identification of causative gene mutations, Sanger sequencing was performed to bidirectionally verify the mutations in the patients and their parents. Results Genetic testing showed 8 compound heterozygous mutations in the COL7A1 gene in the 4 cases. Case 1 was diagnosed with moderate generalized RDEB, and inherited a paternal mutation c.7828C>T and a maternal mutation c.448G> A; case 2 was also diagnosed with moderate generalized RDEB, and inherited a paternal mutation c.3625_3635del and a maternal mutation c.2726_2728del; case 3 was diagnosed with localized RDEB, carrying a paternal mutation c.682+1G>A and an allelic mutation c.5532+1G>A, but the mutation c.5532+1G>A was not identified in the DNA extracted from the parental peripheral blood samples; case 4 was diagnosed with severe generalized RDEB, and inherited a paternal mutation c.5196delC and a maternal mutation c.500_501insAGGG. Among these mutations, c.2726_2728del and c.5196delC had not been reported previously. Conclusions All the 4 children with RDEB carried compound heterozygous mutations in the COL7A1 gene, which may be the cause of RDEB. The phenotypes of biallelic frameshift mutation carriers appearred more severe than those of carriers of compound heterozygous mutations composed of biallelic splice site, missense and nonsense, frameshift and amino acid deletion or insertion mutations.