类脂蛋白沉积症一家系调查及基因突变检测

Clinical investigation and mutation analysis of ECM1 gene in a family with lipoid proteinosis

目的报道1例来自山东的类脂蛋白沉积症家系，研究其家系成员的细胞外基质蛋白（ECM1）基因突变。方法类脂蛋白沉积症家系3代8名成员，有2例患者，分别为先证者（III 1）及其母亲（II 2），均表现为睑缘丘疹、舌系带增厚变短及声音嘶哑。间接喉镜检查显示声带浸润增厚。睑缘及喉部黏膜组织病理检查均提示真皮透明蛋白样物质沉积，PAS染色强阳性，淀粉酶染色阴性，病理诊断符合类脂蛋白沉积症。采用DNA直接测序检测家系8例成员ECM1基因，巢式PCR琼脂糖凝胶电泳对患者的ECM1编码区进行基因突变分析。取100例正常汉族人基因组DNA样品做对照。结果2例患者均为遗传复合体，先证者母亲（112）ECM1的两个等位基因分别存在3个错义突变（p．P169T，P．A44T，p．R392W）。先证者除了从其母亲遗传来的一个错义突变外（p．P169T），还有从其父亲（II 1）遗传来的一个同义突变（c．879G〉A），这个突变产生一个潜在的剪切受体位点“AG”，巢式PCR琼脂糖凝胶电泳结果和PCR产物测序结果证实，该同义突变导致ECM1基因的剪切发生改变。结论本类脂蛋白沉积症家系存在新的ECM1基因同义突变导致的剪切突变。

Objective To report a family with lipoid proteinosis （LP） from Shandong province and to analyze mutations in the extracellular matrix protein 1 （ECM1） gene in this family. Methods Eight members in a threegeneration family with LP were clinically investigated, and two patients were identified to suffer from LP, including the proband （ HI 1 ） and her mother （ II 2）. Both of the patients presented with papules on the palpebral margin, short and thick lingual frenum, and hoarseness. Indirect laryngoscopy showed infiltrating and thickening of the vocal cord. Pathological examination of lesions on the palpebral margin and laryngeal mucosa revealed deposits of hyaline-like material in the dermis, which was strongly positive for periodic acid-Schiff （PAS） staining and resistant to diastase digestion. The pathological diagnosis was LP. Blood samples were collected from all the family members and 100 ethnically matched, unrelated and unaffected Chinese human controls followed by DNA extraction. PCR and sequencing were performed to detect the ECM1 gene, and nested PCR followed by agarose gel electrophoresis to analyze mutations in the coding region of the ECM 1 gene. Results Both of the two patients were compound heterozygotes. Three missense mutations, incluing p.P169T, p.A44T and p.R392W, were found in the ECM1 gene of the affected mother, with p.P169T in one allele and p.A44T as well as p.R392W in the other. The girl patient inheried the missence mutation p.P169T from her mother and a synonymous mutation c.879G 〉 A from her father （ II 1 ）. Nested PCR showed that the c.978G 〉 A mutation generated a splice-acceptor site ＂AG＂, which leaded to a splicing defect. Conclusion A novel synonymous spliee-acceptor site mutation c.879G 〉 A in the ECM1 gene is identified in the family with LP.