Gene expression profiling of amniotic fluid mesenchymal stem cells of monozygotic twins discordant for trisomy 21.

Down syndrome is one of the most common chromosomal disorders and yet our understanding about the dysregulated genes in this disease is limited. Through this case study, we investigated the gene expression profile of primary amniotic fluid mesenchymal stem cells (AFMSCs) isolated from the amniotic sac of monozygotic twins discordant for trisomy 21 with one fetal hydrops at 17 weeks of gestation. AFMSCs were cultured to analyze the gene expression profiles for the human transcriptome array. Gene ontology was used to evaluate dysregulated gene functions. Total 25,799 genes were identified such that 65 were up-regulated (0.25%) and 111 were down-regulated (0.43%) with a log2 fold change trisomy 21/euploidy (log2 [FC]) > 1, p < 0.01). 16 genes were selected and verified by qRT-PCR, which showed compatible result with transcriptome array. At the chromosome level, chromosome 21 was found to carry the highest percentage of up-regulated genes (2.13%, 7/329 genes) with the highest mean log2 [FC] (0.23, p < 10-5), particularly on 21q22.3. There were eight segments with significant mean log2 [FC] on chromosomes 1, 6, 11, and 21 for upregulation, and on chromosomes 16, 17, and 19 for downregulation, indicating a pattern of dysregulated genes clustering in domains along the genome. Gene ontology showed the identified genes associated with extracellular matrix organization (11 genes, p = 5.1 × 10-6) and central nervous system development (8 genes, p = 6.0 × 10-5). Using transcriptome analysis of the AFMSCs of monozygotic twins discordant for trisomy 21, we report the dysregulated genes involved in Down syndrome, their predominance on chromosome 21, and the cluster pattern on the whole genome.