Methods to increase the percentage of free fetal DNA recovered from the maternal circulation.
Methods to increase the percentage of free fetal DNA recovered from the maternal circulation.
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DOI：
10.1097/01.ogx.0000134241.78653.43
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发表时间：
2004-03
期刊：
影响因子：
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通讯作者：
R. Dhallan;W. Au;S. Mattagajasingh;Sarah E. Emche;P. Bayliss;M. Damewood;Michael Cronin;Victoria B Chou;M. Mohr
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文献类型：
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作者：
R. Dhallan;W. Au;S. Mattagajasingh;Sarah E. Emche;P. Bayliss;M. Damewood;Michael Cronin;Victoria B Chou;M. Mohr
背景使用游离胎儿DNA的非侵入性产前诊断测试提供了一种替代侵入性测试及其伴随的风险;然而，游离胎儿DNA存在于母体循环中的比例很低，这阻碍了非侵入性测试的发展。目的验证甲醛减少细胞裂解可增加母血中胎儿游离DNA相对百分比的假设。设计、设置和患者：研究的第一阶段于2002年1月至2月在美国的一个临床研究中心进行;从10名孕妇中各采集2份血液样本，并测定经甲氨蝶呤处理和未经甲氨蝶呤处理的样本中游离胎儿DNA的百分比。研究的第二阶段从2002年3月至2003年5月进行，并测量了69个经甲氨蝶呤处理的母体血液样本中游离胎儿DNA的百分比，这些样本来自美国16个州的27个临床站点。主要观察指标：孕妇外周血中胎儿游离DNA的百分比。结果：在研究的第一阶段，未处理样品中游离胎儿DNA的平均百分比为7.7%（范围，0.32%-40%），而甲酰胺处理样品中游离胎儿DNA的平均百分比为20.2%（范围，1.6%-40%）（差异P = 0.02）。在第二阶段，从69份甲氨蝶呤处理的母体血液样品中获得了25%（范围：3.1%至>50%）游离胎儿DNA的中位数。在这项研究中，大约59%的样本具有25%或更高的胎儿DNA，只有16%的样本具有低于10%的胎儿DNA。此外，本研究中27.5%的样本具有50%或更高的胎儿DNA。结论在母体血液样品中加入甲醛，再加上仔细的处理方案，增加了游离胎儿DNA的相对百分比，为开发无创产前诊断测试以区分母体循环中胎儿DNA和母体DNA提供了基础。
CONTEXT Noninvasive prenatal diagnostic tests using free fetal DNA provide an alternative to invasive tests and their attendant risks; however, free fetal DNA exists in the maternal circulation at low percentages, which has hindered development of noninvasive tests. OBJECTIVE To test the hypothesis that using formaldehyde to reduce cell lysis could increase the relative percentage of free fetal DNA in samples of maternal blood. DESIGN, SETTING, AND PATIENTS The first phase of the study was conducted from January through February 2002 at a single US clinical site; 2 samples of blood were collected from each of 10 pregnant women, and the percentage of free fetal DNA in formaldehyde-treated and untreated samples was determined. The second phase of the study was conducted from March 2002 through May 2003, and measured the percentage of free fetal DNA in 69 formaldehyde-treated samples of maternal blood obtained from a network of 27 US clinical sites in 16 states. MAIN OUTCOME MEASURE Percentage of free fetal DNA in samples of maternal blood. RESULTS In the first phase of the study, the mean percentage of free fetal DNA in the untreated samples was 7.7% (range, 0.32%-40%), while the mean percentage of free fetal DNA in the formaldehyde-treated samples was 20.2% (range, 1.6%-40%) (P =.02 for difference). In the second phase, a median of 25% (range, 3.1% to >50%) free fetal DNA was obtained for the 69 formaldehyde-treated maternal blood samples. Approximately 59% of the samples in this study had 25% or greater fetal DNA, and only 16% of the samples had less than 10% fetal DNA. In addition, 27.5% of the samples in this study had 50% or greater fetal DNA. CONCLUSION Addition of formaldehyde to maternal blood samples, coupled with careful processing protocols, increases the relative percentage of free fetal DNA, providing a foundation for development of noninvasive prenatal diagnostic tests to distinguish fetal DNA from maternal DNA in the maternal circulation.