Abstract: Objective To investigate the expression profiles and chromosome distribution characteristics of the whole-genome miRNAs in Down syndrome (DS) fetus. Methods Illumina deep sequencing technology was conducted to evaluate the miRNAs expression in 6 pairs of fetal cord blood mononuclear cells (CBMCs) samples from DS fetus (DS group) and normal fetus (control group), the characteristics of miRNA expression profiles and chromosome distribution were confirmed by comparing with human genome. Results Of 395 identified miRNAs encoded by 316 miRNA genes, 149 miRNAs were significantly differentially expressed (6 miRNAs up-regulated and 143 miRNAs down-regulated in DS group)，51 miRNAs were specifically expressed in the control fetal CBMCs. For the14 human chromosome 21 (Hsa21) derived miRNA genes, one miRNA (miR-802) was up-regulated in the DS group, and 4 miRNAs (let-7c, miR-99a, miR-125b and miR-155) were down-regulated in the DS group, and other Hsa21-derived miRNA genes were not expressed in both group. Although the chromosome distribution of expressed miRNA genes was similar in both samples, the chromosome distribution of miRNA expression abundance was different. DS group was major scattered in 8、16、17 and 21 chromosome, while the normal group was major scattered in 3、8、14、16、17 and 21 chromosome. Conclusion The DS fetal CBMCs have its own specific miRNA expression profiles and chromosome distribution characteristics. The miRNAs encoded by the chromosome with differentially distribution of expression abundance may play an important role in the development of the DS clinical symptoms.

Key words: MicroRNA, Down syndrome, Illumina sequencing, Expression profile