锁骨颅骨发育不良家系致病基因突变及蛋白结构变化

Identification of pathogenic gene mutation and analysis of protein model in a family with cleidocranial dysplasia

目的检测一个锁骨颅骨发育不良综合征(CCD)家系RUNX2基因突变情况,分析突变体蛋白结构的变化。方法对家系患者进行X线片检查,抽取外周静脉血,提取基因组DNA,采用聚合酶链反应(PCR)扩增RUNX2基因并测序,对测序结果进行Blast分析。运用Swiss-Model软件预测,SWISS-Pdb、RasMol浏览器分析突变体蛋白构像。结果 CCD家系患者RUNX2基因编码序列在外显子3发生错义突变c.674G>T(p.R225L)。蛋白结构预测分析显示,突变体蛋白由于亲水性精氨酸为疏水性的亮氨酸所替代,引起分子内部分氢键基团丢失以及分子表面静电势能改变。结论 RUNX2基因c.674G>T(p.R225L)杂合突变是该家系发病的分子基础,氨基酸序列的改变对蛋白质的空间结构产生影响。

Objective To identify the RUNX2 gene mutation in one family with cleidocranial dysplasia（ CCD）,and to analyze protein model of the mutation of RUNX2 gene. Methods Radiological examination was performed,and the peripheral venous blood of the patients was collected. Genomic DNA was extracted,and the RUNX2 gene was amplified by polymerase chain reaction（ PCR）. DNA sequences were analyzed with the Blastn program. The protein structures of the mutant RUNX2 gene were predicted by Swiss-Model software and viewed in SWISS-Pdb,and Ras Mol Viewer. Results A heterozygous missense mutation c. 674 G〉 T（ p. R225L） in exon 3 of the RUNX2 gene was detected in this family. The mutant RUNX2 gene lost some intra-molecular hydrogen bond,and electrostatic potential energy on molecular surface. Conclusion RUNX2 gene heterozygous mutations c. 674 G〉 T（ p. R225L） is the molecular basis for pathogenesis of this family. The change of amino acid sequence influences the structure of protein.