【摘要】 目的:对2个多发性骨软骨瘤(multiple exostoses)小家系中的先证者进行致病基因EXT1和EXT2编码序列的突变检测,寻找致病性突变。方法:应用PCR扩增EXT1和EXT2基因的编码区及外显子-内含子交界区,对产物进行直接测序。在50个正常对照中进行新发现突变位点的PCR测序分析,以排除多态性。结果:家系1的先证者检测到1个EXT2基因的已知突变c.668G>C(p.Arg223Pro),该错义突变使精氨酸变成脯氨酸;家系2的先证者于EXT2基因中检测到1个国际数据库中尚未报道的新突变c.950delT(p.Phe317SerfsX15),患者父母均未检测到此突变,故此突变为一个de novo突变。该突变引起开放阅读框架移位,提前引入终止密码子,导致蛋白质分子的截断,即部分exostosin结构域和全部glyco-transf-64结构域的丢失。结论:本文发现的EXT2基因的新生及已知突变是引起本研究中多发性骨软骨瘤患者发病的分子机制,可用于临床的分子诊断。更多还原

【Abstract】 AIM: To investigate the mutations of EXT1 and EXT2 genes in the probands of 2 families with multiple exostoses.METHODS: All coding exons and exon-intron boundaries of EXT1 and EXT2 genes were amplified by PCR.The PCR products were sequenced.Fifty normal subjects were also sequenced for the novel mutation in EXT2.RESULTS: A known mutation c.668G>C(p.Arg223Pro) in EXT2 gene was detected in family 1,the missense mutation replaced arginine with proline at codon 223.A novel mutation c.950delT(p.Phe317SerfsX15) in EXT2 was detected in the proband of family 2.This mutation was undetectable in her parents,indicating a de novo mutation.This mutation caused the shift of open reading frame,thus introducing a premature termination and resulting in truncation of the 388 amino acids at the C terminus,wiping out part of the exostosin domain and the whole glyco-transf-64 domain of the protein.CONCLUSION: Our results show that the mutations c.668G>C(p.Arg223Pro) and c.950delT(p.Phe317SerfsX15) in EXT2 gene indicate the molecular mechanism for the development of multiple exostoses in the families.The results can be used for molecular diagnosis.更多还原