Systematic search for placental DNA-methylation markers on chromosome 21: Toward a maternal plasma-based epigenetic test for fetal trisomy 21
Systematic search for placental DNA-methylation markers on chromosome 21: Toward a maternal plasma-based epigenetic test for fetal trisomy 21
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DOI：
10.1373/clinchem.2007.098731
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发表时间：
2008-03-01
影响因子：
9.3
通讯作者：
Lo, Y. M. Dennis
中科院分区：
文献类型：
--
作者：
Chim, Stephen S. C.;Jin, Shengnan;Lo, Y. M. Dennis
背景技术背景：母体血浆中胎儿DNA的存在代表了用于非侵入性产前诊断的胎儿遗传物质的来源;然而，共存的背景母体DNA使此类胎儿DNA中的非整倍性分析复杂化。最近，18号染色体上的SERPINB 5基因被证明在胎盘和母体血细胞中表现出不同的DNA甲基化模式，并且母体血浆中胎盘来源的低甲基化SERPINB 5的等位基因比率进一步被证明可用于胎儿18三体的非侵入性检测。为了开发一种类似的方法用于21三体的非侵入性检测，我们使用甲基化敏感的单核苷酸引物延伸和/或亚硫酸氢盐测序来系统地搜索114个CpG岛（CGI）-76%。在21号染色体上的149个CGIs中，通过生物信息学标准确定了差异甲基化DNA模式。CpG位点的甲基化指数（MI）被估计为在该位点甲基化的分子的比例。我们鉴定了22个CGIs，它们含有CpG位点，（MI = 0.00）在母体血细胞中和胎盘中甲基化（MI范围，0.22-0.65），或在母体血细胞中完全甲基化（MI = 1.00）和在胎盘中低甲基化（MI范围，0.00-0.75）。我们检测到，第一次，胎盘DNA甲基化模式在21号染色体上的母体血浆在怀孕期间，观察其产后clearance.CONCLUSION：22（19%）的114个研究CGIs的21号染色体上显示胎盘和母体血细胞样品之间的表观遗传差异，这些CGIs可能提供了一个丰富的来源标记物的无创产前诊断。(c)2008年美国临床化学协会。
BACKGROUND: The presence of fetal DNA in maternal plasma represents a source of fetal genetic material for noninvasive prenatal diagnosis; however, the coexisting background maternal DNA complicates the analysis of aneuploidy in such fetal DNA. Recently, the SERPINB5 gene on chromosome 18 was shown to exhibit different DNA-methylation patterns in the placenta and maternal blood cells, and the allelic ratio for placenta-derived hypomethylated SERPINB5 in maternal plasma was further shown to be useful for noninvasive detection of fetal trisomy 18.METHODS: To develop a similar method for the non-invasive detection of trisomy 2 1, we used methylation-sensitive single nucleotide primer extension and/or bisulfite sequencing to systematically search 114 CpG islands (CGIs)-76% of the 149 CGIs on chromosome 21 identified by bioinformatic criteria-for differentially methylated DNA patterns. The methylation index (MI) of a CpG site was estimated as the proportion of molecules methylated at that site.RESULTS: We identified 22 CGIs which were shown to contain CpG sites that were either completely unmethylated (Ml = 0.00) in maternal blood cells and methylated in the placenta (Ml range, 0.22-0.65), or completely methylated (MI = 1.00) in maternal blood cells and hypomethylated in the placenta (Ml range, 0.00-0.75). We detected, for the first time, placental DNA-methylation patterns on chromosome 21 in maternal plasma during pregnancy and observed their postpartum clearance.CONCLUSION: Twenty-two (19%) of the 114 studied CGIs on chromosome 21 showed epigenetic differences between samples of placenta and maternal blood cells; these CGIs may provide a rich source of markers for noninvasive prenatal diagnosis. (c) 2008 American Association for Clinical Chemistry.