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Introduction Down syndrome (DS) is the most common aneuploidy, caused by an extra copy of all or part of chromosome 21 (chr21). Differential microRNA (miRNA) expression is involved in many human diseases including DS. However, the genome-wide changes in miRNA expression in DS fetal placentas have yet to be determined, and the function of these changes is also unclear. Methods We profiled genome-wide miRNA expression in placenta samples from euploid or DS fetuses by using microarray technology and predicted the functions of differentially expressed miRNAs using bioinformatics tools. Results Thirty-four miRNAs were significantly differentially expressed in the DS placenta compared with the normal placenta (16 up-regulated and 18 down-regulated). However, expression of chr21-derived miRNAs did not change. Predicted target genes included 7434 genes targeted by up-regulated miRNAs and 6071 genes targeted by down-regulated miRNAs. Seventy-six of these target genes were located on chr21 (10 genes controlled by down-regulated miRNAs and 34 genes by up-regulated miRNAs, and 32 genes by both). Target genes on chr21 were significantly associated with DS and DS-related disorders, such as mental retardation, neurobehavioral manifestations, and congenital abnormalities. Discussion To our knowledge, this is the first genome-wide study to comprehensively survey placental miRNAs in DS fetuses. Our results provide new insight into miRNA expression in placentas of fetuses with DS. Additionally, our findings indicate that the differentially expressed miRNAs in the DS placenta may potentially affect various pathways related to DS pathogenesis.

Introduction To investigate the association between pregnancies with small for gestational age (SGA) neonates and the concentration of cell-free fetal DNA or cell-free total DNA in maternal plasma during the first and second trimesters using tissue-specific epigenetic characteristics of the SERPINB5 gene. Methods A nested case–control study was conducted with maternal plasma collected at 11 to 26 gestational weeks from 51 women with SGA neonates and 102 controls. We performed a real-time quantitative methylation-specific PCR to quantify concentrations of unmethylated- SERPINB5 (U- SERPINB5 ) as a cell-free fetal DNA marker and methylated- SERPINB5 (M- SERPINB5 ) as a cell-free total DNA marker. Results A positive correlation was observed between U- SERPINB5 and M- SERPINB5 concentrations in both control ( r = 0.363, p r = 0.548, p SERPINB5 or M- SERPINB5 was significantly positive correlated with gestational age at sampling in both controls (U- SERPINB5 : r = 0.397, p SERPINB5 : r = 0.275, p = 0.005) and SGA (U- SERPINB5 : r = 0.274, p = 0.052; M- SERPINB5 : r = 0.439, p = 0.001). However, the concentration of U- SERPINB5 or M- SERPINB5 was not correlated with birthweight. At 11–14 weeks, U- SERPINB5 and M- SERPINB5 concentrations in SGA did not differ significantly from those of controls. There were also no statistically significant differences in the concentrations of U- SERPINB5 and M- SERPINB5 between SGA and controls at 15–26 weeks of gestation. Discussion Our findings suggest that U- SERPINB5 and M- SERPINB5 concentrations in maternal plasma during early pregnancy are not associated with pregnancies who delivered SGA neonates.