Down syndrome (DS), the most common human aneuploidy, is associated with oxidative stress, which contributes to morphological abnormalities, immune dysfunction, cognitive impairment and accelerated ageing. This article aims to provide an overview of the studies on oxidative stress in DS, in particular the investigation of endogenous and exogenous antioxidants, with a focus on endogenous systems. A literature search in MEDLINE and Scopus based on the PRISMA 2020 criteria revealed 41 relevant studies that mainly analysed blood samples (plasma or serum) and occasionally saliva or urine. The findings suggest that oxidative stress in DS is multifactorial and results from an imbalance of superoxide dismutase activity, overexpression of genes on chromosome 21, mitochondrial dysfunction and inflammation. Despite extensive studies over the decades, new sources and mechanisms for oxidative stress in DS continue to emerge, further highlighting the complexity of DS. The recognition that oxidative stress is a hallmark of DS emphasises the need to develop more sensitive and specific methods to detect it and to investigate the associated metabolic pathways in DS in more detail. The expansion of in vivo studies could facilitate the development of targeted interventions aimed at mitigating oxidative damage and ultimately improving outcomes for individuals with DS.

Specific markers for colorectal cancer (CRC), preceded by colorectal adenoma (pre-CRC), are lacking. This study aimed to investigate whether microRNAs (miR-19a-3p, miR-92a-3p, miR-193a-3p, and miR-210-3p) from tissues and exosomes are potential CRC biomarkers and compare them to existing biomarkers, namely carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9. MiRNA was isolated in the samples of 52 CRC and 76 pre-CRC patients. Expression levels were analyzed by RT-qPCR. When comparing pre-CRC and CRC tissue expression levels, only miR-193a-3p showed statistically significant result (p < 0.0001). When comparing the tissues and exosomes of CRC samples, a statistically significant difference was found for miR-193a-3p (p < 0.0001), miR-19a-3p (p < 0.0001), miR-92a-3p (p = 0.0212), and miR-210-3p (p < 0.0001). A receiver-operating characteristic (ROC) curve and area under the ROC curve (AUC) were used to evaluate the diagnostic value of CEA, CA 19-9, and miRNAs. CEA and CA 19-9 had good diagnostic values (AUCs of 0.798 and 0.668). The diagnostic value only of miR-193a-3p was highlighted (AUC = 0.725). The final logistic regression model, in which we put a combination of CEA concentration and the miR-193a-3p expression level in tissues, showed that using these two markers can distinguish CRC and pre-CRC in 71.3% of cases (AUC = 0.823). MiR-193a-3p from tissues could be a potential CRC biomarker.