There is an urgent need to identify novel noninvasive biomarkers for Alzheimer disease (AD) diagnosis. Recent advances in blood-based measurements of phosphorylated tau (pTau) species are promising but still insufficient to address clinical needs. Epigenetics has been shown to be helpful to better understand AD pathogenesis. Epigenetic biomarkers have been successfully implemented in other medical disciplines, such as oncology. The objective of this study was to explore the diagnostic accuracy of a blood-based DNA methylation marker panel as a noninvasive tool to identify patients with late-onset Alzheimer compared with age-matched controls.

A case-control study was performed. Blood DNA methylation levels at 46 cytosine-guanine sites (21 genes selected after a comprehensive literature search) were measured by bisulfite pyrosequencing in patients with "probable AD dementia" following National Institute on Aging and the Alzheimer's Association guidelines (2011) and age-matched and sex-matched controls recruited at Neurology Department-University Hospital of Navarre, Spain, selected by convenience sampling. Plasma pTau181 levels were determined by Simoa technology. Multivariable logistic regression analysis was performed to explore the optimal model to discriminate patients with AD from controls. Furthermore, we performed a stratified analysis by sex.

The final study cohort consisted of 80 patients with AD (age: median [interquartile range] 79 [11] years; 58.8% female) and 100 cognitively healthy controls (age 77 [10] years; 58% female). A panel including DNA methylation levels at NXN, ABCA7, and HOXA3 genes and plasma pTau181 significantly improved (area under the receiver operating characteristic curve 0.93, 95% CI 0.89–0.97) the diagnostic performance of a single pTau181-based model, adjusted for age, sex, and APOE 4 genotype. The sensitivity and specificity of this panel were 83.30% and 90.00%, respectively. After sex-stratified analysis, HOXA3 DNA methylation levels showed consistent association with AD.

These results highlight the potential translational value of blood-based DNA methylation biomarkers for noninvasive diagnosis of AD.

Research Ethics Committee of the University Hospital of Navarre (PI17/02218).

迫切需要确定用于阿尔茨海默病（AD）诊断的新型非侵入性生物标志物。磷酸化 tau (pTau) 物种的血液测量的最新进展令人鼓舞，但仍不足以满足临床需求。表观遗传学已被证明有助于更好地了解 AD 发病机制。表观遗传生物标志物已成功应用于肿瘤学等其他医学学科。本研究的目的是探讨基于血液的 DNA 甲基化标记物组作为无创工具的诊断准确性，以与年龄匹配的对照相比识别迟发性阿尔茨海默病患者。

进行了病例对照研究。根据国家老龄化研究所和阿尔茨海默病协会指南（2011）和年龄匹配，通过亚硫酸氢盐焦磷酸测序法测量了 46 个胞嘧啶-鸟嘌呤位点（综合文献检索后选择的 21 个基因）的血液 DNA 甲基化水平。以及在西班牙纳瓦拉大学医院神经科招募的性别匹配对照，通过方便抽样进行选择。通过 Simoa 技术测定血浆 pTau181 水平。进行多变量逻辑回归分析以探索区分 AD 患者与对照组的最佳模型。此外，我们还按性别进行了分层分析。

最终研究队列由 80 名 AD 患者（年龄：中位[四分位距]79 [11]岁；58.8% 女性）和 100 名认知健康对照者（年龄 77 [10] 岁；58% 女性）组成。包含NXN、ABCA7和HOXA3基因以及血浆 pTau181的 DNA 甲基化水平的面板显着改善了基于年龄的单一 pTau181 模型的诊断性能（受试者工作特征曲线下面积 0.93，95% CI 0.89–0.97） 、性别和APOE 4 基因型。该小组的敏感性和特异性分别为 83.30% 和 90.00%。经过性别分层分析后，HOXA3 DNA 甲基化水平显示与 AD 一致相关。

这些结果凸显了基于血液的 DNA 甲基化生物标志物对于 AD 无创诊断的潜在转化价值。

纳瓦拉大学医院研究伦理委员会 (PI17/02218)。