Here, we show that DYRK1A deficiency (loss-of-function) leads to a significant reduction in ACE2 expression, but whether DYRK1A overexpression (gain-of-function) in Down syndrome is sufficient to up-regulate ACE2 in humans and subsequently contribute to COVID-19 severity remains to be seen and warrants additional investigation. This evidence concerns the gene DYRK1A and Down syndrome.