MicroRNA profiling and discovery by deep sequencing cord blood from Down syndrome fetuses

To investigate the expression characteristic of miRNAs during the development of Down syndrome (DS) fetuses and to identify whether another miRNA gene resides in the Hsa21, we employed high-throughput Solexa sequencing technology to comprehensively characterize the miRNA expression profiles of both DS and normal fetal cord blood mononuclear cells (CBMCs). In total, 200 of 395 identified miRNAs were significantly differentially expressed (fold change > 2.0 and P-value < 0.001) and 2 of 181 candidate novel miRNAs were identified as residing within the "Down syndrome critical region" of human chromosome 21 (chr21q22.2-22.3). Additionally, 7 of 14 Hsa21-derived miRNAs genes were detected that three miRNAs (hsa-miR-802, miR-3648, miR-3687) were up-regulated more than 50% and four miRNAs (hsa-miR-99a, let-7c, miR-125b-2, miR-155) were down-regulated in the DS fetal CBMCs compared with the control. Bioinformatics analyses revealed that abnormally expressed miRNAs were major associated with the regulation of transcription, gene expression, cellular biosynthetic process, macromolecule biosynthetic process and nucleic acid metabolic process. The data obtained in our study provides a considerable insight into understanding the expression characteristic of miRNAs in the DS fetal hemopoietic system and the differentially expressed miRNAs may be involved in the hemopoietic abnormalities and the immune defects of DS fetus and newborns. Overall design: A total of 6 DS and 6 matched control fetal cord blood samples (18-22 weeks of gestation) were collected. Three DS and 3 control cord blood samples were combined to form pooled DS and control cord blood samples, respectively, for small RNA library construction and Solexa sequencing. The remaining samples were used as the validation set to confirm the miRNA differential expression patterns by qRT-PCR.

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Xu Y, Li W, Liu X, Ma H, Tu Z, Dai Y