Laboratory of Medical Genetics, Medical Research Institute, Cheil General Hospital and Women's Healthcare Center, Seoul, Korea.
BMC Med Genomics. 2014 Jan 8;7:1. doi: 10.1186/1755-8794-7-1.
Non-invasive prenatal testing of trisomy 21 (T21) is being actively investigated using fetal-specific epigenetic markers (EPs) that are present in maternal plasma. Recently, 12 EPs on chromosome 21 were identified based on tissue-specific epigenetic characteristics between placenta and blood, and demonstrated excellent clinical performance in the non-invasive detection of fetal T21. However, the disease-specific epigenetic characteristics of the EPs have not been established. Therefore, we validated the disease-specific epigenetic characteristics of these EPs for use in non-invasive detection of fetal T21.
We performed a high-resolution tiling array analysis of human chromosome 21 using a methyl-CpG binding domain-based protein (MBD) method with whole blood samples from non-pregnant normal women, whole blood samples from pregnant normal women, placenta samples of normal fetuses, and placenta samples of T21 fetuses. Tiling array results were validated by bisulfite direct sequencing and qPCR.
Among 12 EPs, only four EPs were confirmed to be hypermethylated in normal placenta and hypomethylated in blood. One of these four showed a severe discrepancy in the methylation patterns of T21 placenta samples, and another was located within a region of copy number variations. Thus, two EPs were confirmed to be potential fetal-specific markers based on their disease-specific epigenetic characteristics. The array results of these EPs were consisted with the results obtained by bisulfite direct sequencing and qPCR. Moreover, the two EPs were detected in maternal plasma.
We validated that two EPs have the potential to be fetal-specific EPs which is consistent with their disease-specific epigenetic characteristics. The findings of this study suggest that disease-specific epigenetic characteristics should be considered in the development of fetal-specific EPs for non-invasive prenatal testing of T21.
非侵入性产前检测 21 三体（T21）正积极使用胎儿特异性表观遗传标记物（EPs）进行研究，这些标记物存在于母体血浆中。最近，根据胎盘和血液之间组织特异性的表观遗传特征，在 21 号染色体上鉴定出了 12 个 EPs，并在非侵入性检测胎儿 T21 方面表现出了优异的临床性能。然而，这些 EPs 的疾病特异性表观遗传特征尚未建立。因此，我们验证了这些 EPs 的疾病特异性表观遗传特征，以用于非侵入性检测胎儿 T21。
我们使用基于甲基化-CpG 结合域蛋白（MBD）的方法，对非妊娠正常女性的全血样本、妊娠正常女性的全血样本、正常胎儿的胎盘样本和 T21 胎儿的胎盘样本进行了 21 号染色体的高分辨率平铺阵列分析。平铺阵列结果通过亚硫酸氢盐直接测序和 qPCR 进行验证。
在 12 个 EPs 中，只有 4 个 EPs 被证实正常胎盘中呈高甲基化，血液中呈低甲基化。其中一个在 T21 胎盘样本中表现出严重的甲基化模式差异，另一个位于拷贝数变异区域内。因此，根据其疾病特异性表观遗传特征，有两个 EPs 被确认为潜在的胎儿特异性标记物。这些 EPs 的阵列结果与亚硫酸氢盐直接测序和 qPCR 的结果一致。此外，这两个 EP 在母体血浆中被检测到。
我们验证了两个 EP 具有成为胎儿特异性 EP 的潜力，这与它们的疾病特异性表观遗传特征一致。本研究结果表明，在开发用于 T21 非侵入性产前检测的胎儿特异性 EP 时，应考虑疾病特异性表观遗传特征。
