Development And Clinical Application Of Molecular Diagno

在过去的十年里，越来越多的基因与阿尔茨海默病有关。最近，高同型半胱氨酸血症和被怀疑导致高同型半胱氨酸血症的基因突变被认为可能是阿尔茨海默病的诱因。5，10-亚甲基四氢叶酸还原酶(MTHFR)催化5，10-亚甲基四氢叶酸转化为5-甲基四氢叶酸，5-亚甲基四氢叶酸是叶酸的主要循环形式，也是同型半胱氨酸再甲基化的辅助因子。两个不同的突变，一个在碱基位置677(C到T的转变，导致MTHFR酶的“不耐热”变体)和另一个在碱基对1298(A到C的转变)，现在被怀疑导致同型半胱氨酸水平增加和阿尔茨海默病的风险增加。为了研究这些基因突变在阿尔茨海默病中的可能作用，我们发展了实用的PCR-单链构象多态(PCR-SSCP)方法，用于在大量患者群体中进行研究。这两种方法都已与传统的聚合酶链式反应-限制性片段长度多态性(PCR-RFLP)分析进行了验证，并通过DNA测序进行了确认。为了分析这两种MTHFR基因突变对血浆同型半胱氨酸的影响，我们还用高效液相色谱法测定了这些患者的血浆同型半胱氨酸和半胱氨酸水平。在另一项合作研究中，正在对一大批系统性红斑狼疮患者研究载脂蛋白(A)亚型和等位基因可能的致病作用。这些患者经常经历动脉粥样硬化血栓形成事件，寻找这些事件的可靠预测因素具有重要的临床意义。我们的初步发现表明载脂蛋白亚型/等位基因可能是这样的预测因子。

An increasing number of genes have been linked to Alzheimer disease over the past decade. Most recently, hyperhomocysteinemia and gene mutations suspected to cause hyperhomocysteinemia have been suggested as possible contributors to Alzheimer disease. The enzyme 5,10-methylenetetrahydrofolate reductase (MTHFR) catalyzes the conversion of 5,10-methylenetetrahydrofolate into 5-methyltetrahydrofolate, which is the major circulating form of folate and a cofactor in remethylation of homocysteine. Two different mutations, one at base position 677 (C to T transition that results in a "thermolabile" variant of the MTHFR enzyme) and another at base pair 1298 (A to C transition), are now suspected to lead to increased homocysteine levels and increased risk of Alzheimer disease. In order to study the possible role of these gene mutations in Alzheimer disease, we developed practicable PCR-single-strand conformation polymorphism (PCR-SSCP) methods for their study in a large patient population. Both methods have been validated against conventional PCR-restriction fragment-length polymorphism (PCR-RFLP) assays and confirmed by DNA sequencing. In order to analyze the effect of both MTHFR gene mutations on plasma homocysteine, we are also measuring the plasma homocysteine and cysteine levels by an HPLC method in these patients. In another collaborative study, the possible pathogenic role of apolipoprotein(a) isoforms and alleles is being studied in a large cohort of patients with systemic lupus erythematosus. These patients often experience atherothrombotic events and finding reliable predictors for these events is of major clinical importance. Our preliminary findings indicate that apolipoprotetin isoforms/alleles may be such predictors.