散发性Creutzfeldt-Jakob病患者10例prion基因研究

Investigation of prion protein gene in 10 sporadic Creutzfeldt-Jakob disease patients: a new novel mutation of prion protein gene

目的检测10例Creutzfeldt-Jakob病(CJD)患者prion基因(PRNP)外显子突变情况。方法抽取患者外周静脉血,提取DNA,PCR法扩增PRNP外显子后直接测序,并用限制性内切酶NspI检测PRNP 129位点密码子基因型。结果2例肯定CJD患者中,1例PRNP检测未见异常,另1例PRNP第729碱基C被C取代(729G→C),使编码prion第211个氨基酸的密码子GAG变成了GAC,翻译后第211个氨基酸由谷氨酸变为天冬氨酸(E211D)。8例很可能CJD患者中,2例PRNP第751碱基G被A取代(751G→A),使编码prion第219个氨基酸的密码子GAG变成了AAG,翻译后第219个氨基酸由谷氨酸变为赖氨酸(E219K)。10例CJD患者PRNP 129位点密码子基因型都是甲硫氨酸纯合型。结论1例肯定CJD患者的prion基因外显子存在一种新的点突变E211D,这很可能是导致遗传prion病发生的原因。2例很可能CJD患者的prion基因突变E219K,与M129V同属于基因多态性,而不是致病原因。prion基因检测有助于prion病的诊断。

Objective To detect point mutations of the PRNP in 10 sporadic Creutzfeldt-Jakob disease （CJD） patients. Methods Prion protein gene open reading frame was amplified by PCR of genomie DNA extracted from peripheral blood leukoeytes. Products were sequenced and digested with restriction endonuelease Nsp Ⅰ to check the phenotype at eodon 129. Results Two CJD patients were confinned at autopsy. One full sequencing of the PRNP open reading frame revealed normal, but the other revealed a single novel mutation consisting of a cytosine-to-guanine substitution at nueleotide 729,causing asparagine to replace glutamie acid at eodon 211. Among 8 probable CJD patients, 2 full sequencing of the PRNP open reading frame revealed anadenine-to-guanine substitution at nueleotide 751, causing lysine to replace glutamie acid at eodon 219. The patients were methionine homozygosity at eodon 129. Conclusions The E211D mutation was identified in a con-finned CJD patient. The novel point mutation might be associated with familial CJD. However, E219K identified in 2 possible CJD patients was included in polymorphism of the PRNP as well as M129V. Analysis of PRNP plays an important role for diagnose of familial prion disease.