遗传性多发性骨软骨瘤患者EXT基因突变检测一例

Screening for EXT gene mutations in a pedigree with hereditary multiple exostoses

目的对1例遗传性多发性骨软骨瘤患者的EXT1和EXT2基因编码序列进行突变检测,寻找致病突变。方法采集患者及其家系成员外周血,应用PCR技术扩增EXT1和EXT2基因编码区及外显子-内含子交界区,再对产物进行测序。结果发现EXT1基因有7种内含子突变(c.1165-156G>GT、c.1284+66G>GA、c.1536+59G>GT、c.1536+91_99del AGGCTCCCC、c.1537-51A>AG、c.1722+202T>TC、c.1723-103C>CG),发现EXT2基因有6种内含子突变(c.70-80A>AC、c.636-79A>AC、c.1179-18T>TA、c.1595-195C>T、c.1905-51T>TC、c.2035-41T>TC)、1种外显子突变(c.138G>GA,p.E28K)。其中c.1536+91_99del AGGCTCCCC和p.E28K两种突变是新发现的多态位点,其它12种突变均为人类基因突变数据库收率的多态位点。结论未能找到该家系的明确致病基因,该家系的发病是否由EXT1和EXT2基因以外的EXT基因家族突变引起还需进一步的连锁定位分析。

Objective： To investigate the mutations of EXT1 and EXT2 genes in a patient with hereditary multiple exostoses. Methods： All exons of EXTland EXT2 genes for genomic DNA extracted from the patients and her family blood samples were amplified by PCR and sequence using comparative analysis in Mutation Surveyor. Results： For EXT1 gene, 7 intronic mutations （c.1165-156G〉GT, c.1284＋66G〉GA, c.1536＋ 59G〉GT, c.1536＋91_99delAGGCTCCCC, c.1537-51A〉AG, c.1722＋202T 〉TC, c.1723-103C〉CG） were found.For EXT2 gene, 6 intronic mutations （c.70-80A〉AC, c.636-79A〉AC, c.1179-18T 〉TA, c.1595-195C〉T, c.1905-51T〉TC, c.2035-41T〉TC） and 1 exonic mutation （c.138G〉GA, p.E28K） were detected. Among these, 2 mutations （c.1536＋91_99delAGGCTCCCC, c.138G〉GA, p.E28K） are new, while the other 12 mutations are polymorphisms listed by The Human Gene Mutation Database. Conclusion： No pathogenic mutations have been found among all exons of the EXTland EXT2 genes. Linkage analysis is necessary to identify the cause of disease.