Gene Expression Studies in Down Syndrome; What Do They Tell Us about Disease Phenotypes?

Background: Down Syndrome is the most well-studied aneuploidy condition in humans. It is associated with multiple disease phenotypes including cardiovascular, neurological, haemato-logical, and immunological disease processes. In this review paper we aim to discuss the research into gene expression studies performed at the fetal stage of development. Methods: A descriptive review was performed including all papers published on the PubMed database between Septem-ber 1960- September 2022. Results: In the amniotic fluid, genes such as COL6A1 and DSCR1 are affected, causing the phenotypical craniofacial changes. Other genes affected in amniotic fluid in-cluding: GSTT1, CLIC6, ITGB2, C21orf67, C21orf86 and RUNX1. In the placenta, MEST, SNF1LK and LOX were dysregulated, affecting nervous system development. In the brain DYRK1A, DNMT3L, DNMT3B, TBX1, olig2 and AQP4 were found to be dysregulated, affecting the nervous system and intellectual disability. In the cardiac tissues GART, EST2 and ERG found to be dysregulated causing secondary heart field abnormalities. XIST, RUNX1, SON, ERG and STAT1 dysregulated causing myeloproliferative disorders. Conclusions: Differential expression of genes provides clues to the genetic consequences of DS. A better understanding of these processes could eventually to lead to the development of genetic and pharmacological therapies.