Department of Epidemiology; Mailman School of Public Health of Columbia University; New York, NY USA; Department of Environmental Health Sciences; Mailman School of Public Health of Columbia University; New York, NY USA.
Department of Environmental Health Sciences; Mailman School of Public Health of Columbia University; New York, NY USA.
Epigenetics. 2014 Jul;9(7):929-33. doi: 10.4161/epi.28902. Epub 2014 Apr 22.
Many epidemiologic studies of environmental exposures and disease susceptibility measure DNA methylation in white blood cells (WBC). Some studies are also starting to use saliva DNA as it is usually more readily available in large epidemiologic studies. However, little is known about the correlation of methylation between WBC and saliva DNA. We examined DNA methylation in three repetitive elements, Sat2, Alu, and LINE-1, and in four CpG sites, including AHRR (cg23576855, cg05575921), cg05951221 at 2q37.1, and cg11924019 at CYP1A1, in 57 girls aged 6-15 years with blood and saliva collected on the same day. We measured all DNA methylation markers by bisulfite-pyrosequencing, except for Sat2 and Alu, which were measured by the MethyLight assay. Methylation levels measured in saliva DNA were lower than those in WBC DNA, with differences ranging from 2.8% for Alu to 14.1% for cg05575921. Methylation levels for the three repetitive elements measured in saliva DNA were all positively correlated with those in WBC DNA. However, there was a wide range in the Spearman correlations, with the smallest correlation found for Alu (0.24) and the strongest correlation found for LINE-1 (0.73). Spearman correlations for cg05575921, cg05951221, and cg11924019 were 0.33, 0.42, and 0.79, respectively. If these findings are replicated in larger studies, they suggest that, for selected methylation markers (e.g., LINE-1), methylation levels may be highly correlated between blood and saliva, while for others methylation markers, the levels may be more tissue specific. Thus, in studies that differ by DNA source, each interrogated site should be separately examined in order to evaluate the correlation in DNA methylation levels across DNA sources.
许多研究环境暴露与疾病易感性的流行病学研究都测量了白细胞（WBC）中的 DNA 甲基化。一些研究也开始使用唾液 DNA，因为它在大型流行病学研究中通常更容易获得。然而，人们对 WBC 和唾液 DNA 之间的甲基化相关性知之甚少。我们检查了三个重复元件（Sat2、Alu 和 LINE-1）和四个 CpG 位点（包括 AHRR [cg23576855、cg05575921]、2q37.1 处的 cg05951221 和 CYP1A1 处的 cg11924019）中的 DNA 甲基化，这些女孩年龄在 6-15 岁之间，血液和唾液是在同一天采集的。我们通过亚硫酸氢盐-焦磷酸测序测量了所有 DNA 甲基化标记物，除了 Sat2 和 Alu，它们是通过 MethyLight 测定法测量的。唾液 DNA 中测量的甲基化水平低于 WBC DNA 中的甲基化水平，差异范围从 Alu 的 2.8%到 cg05575921 的 14.1%。唾液 DNA 中测量的三个重复元件的甲基化水平均与 WBC DNA 中的甲基化水平呈正相关。然而，Spearman 相关性的范围很广，Alu 的相关性最小（0.24），LINE-1 的相关性最强（0.73）。cg05575921、cg05951221 和 cg11924019 的 Spearman 相关性分别为 0.33、0.42 和 0.79。如果这些发现能够在更大的研究中得到验证，它们表明对于某些甲基化标记物（例如 LINE-1），血液和唾液之间的甲基化水平可能高度相关，而对于其他甲基化标记物，甲基化水平可能更具组织特异性。因此，在不同 DNA 来源的研究中，应分别检查每个检测位点，以评估 DNA 甲基化水平在 DNA 来源之间的相关性。
