ena-DATASET-POPS-31-07-2017-10:37:57:004-1117 - samples

All the samples were obtained from the Pregnancy Outcome Prediction–a prospective cohort study of nulliparous women attending the Rosie Hospital, Cambridge (UK) for their dating ultrasound scan between January 14, 2008, and July 31, 2012. Ethical approval for the study was given by the Cambridgeshire 2 Research Ethics Committee (reference number 07/H0308/163) and all participants provided written informed consent. Cases of preeclampsia (PET) were defined on the basis of the 2013 ACOG criteria and cases of small for gestational age (SGA)infants were confined to severe SGA, i.e. a customized birth weight <5th percentile.

Chorionic villi from the corresponding placentas (free from decidua, visible infarction, calcification, hematoma, or damage) were collected and processed within 30 minutes of separation from the uterus. After repeated washes in chilled phosphate buffered saline, the samples were placed in RNA later (Applied Biosystems) and stored at -80°C. Total placental RNA was extracted using mirVana Isolation Kit (Ambion). For each placenta, approximately 5 mg of tissue were homogenized in the Lysis/Binding solution for 20 sec at 6 m/s using a bead beater (FastPrep24) and Lysing Matrix D Tubes (MP Biomedicals). The samples were then spun at 13,000 rpm for 5 min at 4°C and the supernatants recovered. Afterwards, the manufacturer's instructions were followed. Immediately after the RNA extraction, placental RNA samples were DNase-treated using DNA-free DNA Removal Kit (Ambion), aliquoted, and stored in -80°C. Quantity and quality of the RNA samples were assessed using the Agilent 2100 Bioanalyzer, the Agilent RNA 6000 Nano Kit (Agilent Technologies), and Qubit fluorometer.

Libraries were prepared starting with 300-500 ng of good quality total RNA (RIN ≥7.5) using the TruSeq Stranded Total RNA Library Prep Kit with Ribo-Zero Human/Mouse/Rat (Illumina), according to the manufacturer's instructions. The kit contains 96 uniquely indexed adapter combinations in order to allow pooling of multiple samples prior to sequencing. After determining their size (with the Agilent 2100 Bioanalyzer and the Agilent High Sensitivity DNA Kit by Agilent Technologies) and concentration (by qPCR with the KAPA Illumina ABI Prism Library Quantification Kit, Kapa Biosystems), libraries have been pooled and sequenced (single-end, 125 bp) using a Single End V4 Cluster Kit and an Illumina HiSeq2500 or HiSeq4000 instrument.EGA dataset EGAD00001003508

所有样本均来自「妊娠结局预测」（Pregnancy Outcome Prediction）前瞻性队列研究，研究对象为2008年1月14日至2012年7月31日期间，于英国剑桥罗西医院（Rosie Hospital）接受超声孕周核对的初产妇。本研究经剑桥郡2研究伦理委员会（Cambridgeshire 2 Research Ethics Committee）批准，批准编号为07/H0308/163，所有受试者均签署书面知情同意书。

子痫前期（preeclampsia, PET）的诊断依据2013年美国妇产科医师学会（American College of Obstetricians and Gynecologists, ACOG）标准；小于胎龄儿（small for gestational age, SGA）病例限定为重度小于胎龄儿，即校正出生体重低于第5百分位数。

从对应胎盘（无蜕膜、无可见梗死、钙化、血肿或损伤）获取绒毛膜绒毛，于子宫娩出后30分钟内完成处理。经预冷磷酸盐缓冲液（phosphate buffered saline, PBS）反复冲洗后，将样本置于RNA later（Applied Biosystems）中，于-80℃保存。总胎盘RNA提取采用mirVana分离试剂盒（Ambion）。取约5mg组织，使用珠磨式组织破碎仪（FastPrep24）及MP Biomedicals的Lysing Matrix D管，以6m/s转速在裂解/结合液中均质20秒；随后于4℃、13000rpm离心5分钟，收集上清液，后续严格遵循制造商说明书操作。RNA提取完成后，立即使用DNA-free DNA去除试剂盒（Ambion）对胎盘RNA样本进行DNase处理，分装后于-80℃保存。采用安捷伦2100生物分析仪（Agilent 2100 Bioanalyzer）、安捷伦RNA 6000 Nano试剂盒（Agilent Technologies）及Qubit荧光定量仪，对RNA样本的浓度与质量进行评估。

以300-500ng质量合格的总RNA（RNA完整性指数[RNA Integrity Number, RIN]≥7.5）为起始材料，使用带Ribo-Zero Human/Mouse/Rat的TruSeq链特异性总RNA文库制备试剂盒（Illumina），严格遵循制造商说明书构建测序文库。该试剂盒包含96种唯一索引接头组合，可实现测序前多样本混合。经安捷伦2100生物分析仪与安捷伦高灵敏度DNA试剂盒（Agilent Technologies）检测文库片段大小，采用卡帕生物系统公司（Kapa Biosystems）的KAPA Illumina ABI Prism文库定量试剂盒通过qPCR定量文库浓度后，将文库混合，使用Single End V4簇生成试剂盒及Illumina HiSeq2500或HiSeq4000测序仪进行单端125bp测序。本数据集为欧洲基因组-表型档案（EGA）数据集EGAD00001003508。