精氨酰琥珀酸尿症家系ASL基因内含子突变

Intron mutations of argininosuccinate lyase (ASL) gene exist in a family with argininosuccinic aciduria

目的对1个MS/MS检测表现为瓜氨酸(Cit)增高的遗传代谢性疾病家系进行基因检测和基因的突变分析。方法采集家系成员外周血,提取基因组DNA,用全外显子测序方法进行基因诊断。对未见报道的新突变构建pcDNA3.1(+)真核表达载体,并在体外培养细胞中用Mini-gene工具验证该突变的致病性。结果先证者精氨酰琥珀酸尿症临床诊断明确,在ASL基因上检测到2个致病突变c.281G>T(P.R94L丨p.Arg94Leu)和c.208-15 T>A,该2个突变均未见报道;Mini-gene体外表达证实c.208-15 T>A可造成剪切异常,导致2号内含子13 bp碱基滞留。结论在1个精氨酰琥珀酸尿症家系中发现了ASL基因2个新的致病突变c.208-15 T>A和c.281G>T,丰富了ASL基因的突变谱;Mini-gene对内含子突变研究是一种简单有效的工具。

Objective To perform gene detection and gene mutation analysis in a family with inherited metabolic diseases characterized as increased citrulline(Cit) by the MS/MS assay. Methods The peripheral blood samples were collected from the family members, and genomic DNA was extracted for gene diagnosis, which was performed by the whole exon sequencing method. The novel mutation gene was cloned into pcDNA3.1(+) vector, and its pathogenicity was verified by the Mini-gene assay in cultured cells in vitro. Results The clinical diagnosis of the proband as argininosuccinic aciduria(ASA) was clear. Two pathogenic mutations, c.281 G>T(p.Arg94 Leu) and c.208-15 T>A, were detected in the argininosuccinate lyase(ASL) gene, and they were not reported previously. The Mini-gene expression in vitro confirmed that c.208-15 T>A could cause aberrant splicing, resulting in the retention of 13 bp in intron 2. Conclusion Two new pathogenic mutations of ASL gene, c.208-15 T>A and c.281 G>T, are found in an ASA family, which enriches the mutation profile of ASL gene. The Mini-gene assay is a simple and effective tool for the research of intron mutations.