Wolcott-Rallison综合征一例报告及其EIF2AK3基因突变检测

目的 报道一例Wolcott-Rallison综合征患儿,研究患儿真核生物翻译起始因子-2α-激酶-3基因(eukaryoticinitiation factor 2α kinase 3,EIF2AK3)的突变情况,为该病的临床诊断、基因诊断与遗传咨询提供依据.方法 分析患儿的临床症状、体征、生化检查及骨骼X线检查并做出临床诊断;提取患儿及其父母的基因组DNA,针对EIF2AK3基因设计特异性引物,应用降落聚合酶链式反应(Touch-down PCR)扩增基因的全部外显子及外显子-内含子交界区,对扩增产物进行直接测序分析.结果 (1)9岁4个月男性患儿,身高108 cm,智力相当于6岁儿童发育水平;出生3个月时被诊断为1型糖尿病,正规胰岛素治疗后空腹血糖常高于11.0 mmol/L,最高达23.5 mmol/L;面容异常;肝脏于肋下5 cm,剑突下2 cm;骨骼畸形,X线提示多发性骨骺发育不良.(2)患儿EIF2AK3基因的外显子8中检测到c.1408_1409insT(p.S470FfsX7)杂合突变,外显子9中检测到c.1596T＞A(p.C532X)杂合突变,2个突变位点分别在患儿母亲和父亲的基因中得到验证.结论 Wolcott-Rallison综合征临床特点:新生儿或婴儿早期发生的1型糖尿病,多发性骨骺发育不良,体格和智力发育迟缓,多系统损伤;结合患者临床表现与生化、物理检查,对致病基因EIF2AK3进行突变检测是诊断Wolcott-Rallison 综合征的可靠方法.EIF2AK3基因c.1408_1409insT与c.1596T＞A是导致该患儿出现Wolcott-Rallison综合征表型的致病突变,患儿为EIF2AK3基因突变的遗传复合体,这2个突变在国内外均未见报道,属新突变.

Abstract：

Objective Wolcott-Rallison syndrome(WRS)is a rare autosomal recessive disorder characterized by the association of permanent neonatal or early-infancy insulin-dependent diabetes,multiple epiphyseal dysplasia and growth retardation,and other variable multisystem clinical manifestations.Here we describe a Chinese boy affected by WRS.Genetic testing of his EIF2AK3 gene was performed in order to elucidate molecular variations and subsequently to provide credible genetic counseling for prenatal diagnosis in his family. Method Based on analysis of a nine-year-old boy's clinical symptoms associated with biochemical examination and imaging,the diagnosis of WRS was therefore made.Genomic DNAs were extracted from peripheral blood leukocytes from the boy and his parents with their informed consent for genetic studies.All EIF2AK3 exons and intron-exon boundaries were amplified by Touch-down polymerase chain reaction(Touch-down PCR)and sequenced.Result Direct sequencing of PCR products revealed the presence of a heterozygous T insertion(c.1408_1409insT)in exon 8 of the EIF2AK3 gene leading to frameshifting and termination,and another heterozygous T to A exchange(c.1596T ＞ A)in exon 9 of the EIF2AK3 gene resulting in nonsense C532X mutation. Conclusion Combining mutation screening of EIF2AK3 gene with clinical manifestations and effective examination may provide a reliable diagnostic method for patients.In this research,two novel mutations identified in the Chinese boy locate in the catalytic domain of the EIF2AK3 gene,disrupting the ability of autophosphorylation,leading to the truncated proteins that are unable to phosphorylate the natural substrate,which are responsible for the phenotype of Wolcott-Rallison syndrome.

Two novel EIF2AK3 mutations in a Chinese boy with Wolcott-Rallison syndrome

Objective Wolcott-Rallison syndrome(WRS)is a rare autosomal recessive disorder characterized by the association of permanent neonatal or early-infancy insulin-dependent diabetes,multiple epiphyseal dysplasia and growth retardation,and other variable multisystem clinical manifestations.Here we describe a Chinese boy affected by WRS.Genetic testing of his EIF2AK3 gene was performed in order to elucidate molecular variations and subsequently to provide credible genetic counseling for prenatal diagnosis in his family. Method Based on analysis of a nine-year-old boy's clinical symptoms associated with biochemical examination and imaging,the diagnosis of WRS was therefore made.Genomic DNAs were extracted from peripheral blood leukocytes from the boy and his parents with their informed consent for genetic studies.All EIF2AK3 exons and intron-exon boundaries were amplified by Touch-down polymerase chain reaction(Touch-down PCR)and sequenced.Result Direct sequencing of PCR products revealed the presence of a heterozygous T insertion(c.1408_1409insT)in exon 8 of the EIF2AK3 gene leading to frameshifting and termination,and another heterozygous T to A exchange(c.1596T ＞ A)in exon 9 of the EIF2AK3 gene resulting in nonsense C532X mutation. Conclusion Combining mutation screening of EIF2AK3 gene with clinical manifestations and effective examination may provide a reliable diagnostic method for patients.In this research,two novel mutations identified in the Chinese boy locate in the catalytic domain of the EIF2AK3 gene,disrupting the ability of autophosphorylation,leading to the truncated proteins that are unable to phosphorylate the natural substrate,which are responsible for the phenotype of Wolcott-Rallison syndrome.