基于影像遗传学技术的CLU基因分型及外周血浓度在AD早期诊断中的研究

Lots of previous research found that clumped beta amyloid protein deposition, Tau protein phosphorylation are closely associated with AD, CLU protein is implicated because it could affect the clearance of amyloid protein，and it is regulated by genes. Our previous study found CLU genetic polymorphisms could increase the risk of mild cognitive impairment,it suggests CLU may be new target in early diagnosis and treatment of mild cognitive impairment and alzheimer'disease，but it's not clearly understand about the pathophysiological mechanism. AD was influenced by many other factors beyond genetic elements, genetic research cannot directly, objectively reflects disease's pathogenesis, so it not wise to provide crucial help for clinical diagnosis and treatment. Image genetics as a new cross-disciplinary research mode, it can be used to directly，objectively research on AD. Our image genetics study found that significant differences in volume, structure, metabolism and blood perfusion of brain areas such as the hippocampus in patients with different CLU genotypes, and we had established a analysis approach to monitor and evaluate cognitive impairment using structure and function image. We will use image genetics to clarify the pathogenesis of cognitive and gene polymorphisms though interdisciplinary, many system and aspects，and directly, objectively analyze the association of CLU gene polymorphisms, levels of peripheral blood CLU protein, mRNA with structure and function differences in mild cognitive impairment, AD patients, discuss the role of CLU gene polymorphisms, and eatablish a new mode in early diagnosis of mild cognitive impairment and AD, and provide evidence for new target of early diagnosis and treatment for cognitive impairment and AD.

大量研究发现β淀粉样蛋白沉积、Tau蛋白过度磷酸化与AD的发生密切相关，而影响β淀粉样蛋白清除的CLU蛋白也与AD的发生密切相关，CLU蛋白受到相关编码基因的遗传调控。申请者前期研究发现CLU遗传多态性可增加MCI的风险，提示CLU可能成为MCI、AD早期诊疗的新靶点。AD受遗传及其他多因素的影响，单独的遗传病因学研究不能直接客观地反映疾病的发生机制。影像遗传学作为一种新的学科交叉研究模式，是目前可直接客观研究AD等疾病的新型技术。课题组前期影像遗传学研究发现不同CLU基因型人群在不同脑区存在体积、结构和代谢方面的异常，并建立了联合结构和功能影像监测、评估AD及MCI的方法。本研究拟结合遗传及影像方法，进行多学科交叉，从多系统、多层面阐明CLU基因遗传多态性、外周血CLU蛋白及mRNA浓度在AD中的发病机制，建立其在AD及MCI早期诊断中的新模式，为AD的早期诊断及干预治疗提供新的靶点。

本研究纳入了105名AD患者、90名MCI患者及100名健康对照者，收集了所有纳入研究对象的血液标本、认知功能评分及影像学资料信息。根据生物信息学筛选了CLU基因相关SNPs,重点分析了其rs11136000、rs9331888、rs2279590位点在三组人群的表达情况；根究影像学研究资料，分析了AD患者脑部结构、代谢和功能的异常；分析了AD、MCI患者及正常健康人群外周血CLU蛋白的水平，结合CLU基因多态性进行了相关分析；并结合CLU基因多态性和影像学资料，从影像遗传学角度分析了CLU基因多态性与AD、MCI患者认知改变的相关关系。主要研究结果如下：.1.通过生物信息学方法，结合相关文献，筛选了25个CLU基因相关SNPs；利用HRM技术建立了高通量SNP基因分型平台，分析了105名AD患者、90名MCI患者及100名健康对照者CLU基因多位点SNPs。.2. CLU基因rs11136000和rs9331888位点存在与AD发病相关的等位基因，其中rs11136000位点携带基因型（CC+CT）的发病风险远高于基因型TT（OR=2.410，95%CI=1.101-5.278，P=0.0248）；rs9331888位点，携带等位基因G更易患AD（OR=2.121，95%CI=1.413-3.184，P=0.0030）。.3. AD患者MCI患者外周血CLU蛋白浓度均高于健康对照患者（51.77（34.84,72.82）ug/ml VS 30.06（14.39,46.34）ug/ml，P<0.0001；41.68（26.63,59.81）ug/ml VS 30.06（14.39,46.34）ug/ml，P<0.0001），CLU蛋白浓度水平与rs11136000位点基因型相关，携带CC基因型高于CT、TT基因型，且与MMSE评分呈负相关（P<0.0001）。.4. AD患者全脑及部分特殊脑结构均存在不同程度的灰质密度降低，与AD患者病理改变老年斑和神经原纤维缠绕导致神经元减少和体积缩小，MRI表现为脑结构萎缩相对应；与CT+TT基因型比较，CC基因型在MCI患者及健康对照组均存在多个脑区域灰质浓度GMC、灰质体积GMV和各向异质分数FA的差异，特别是低GMC和低FA提示CC基因型是认知障碍的危险基因型，是AD发病中的危险因素。.