DYRK1A was first described in the fruit fly Drosophila as the mini-brain mutation. The enzyme has been shown to be an important brain development factor. Its abnormal expression is thought to play a role in aberrant brain development, lifelong structural and functional neurological abnormalities, neural degeneration, and neuronal death (Weigel et al 2011). In the case of individuals with Down syndrome, the 1.5x overexpression caused by Trisomy 21 results in retardation and moderate to severe cognitive impairment. DYRK1A is known to be involved at multiple sites of Alzheimer’s disease pathology in DS (Wiseman et al 2015); indeed, most DS patients show early onset of Alzheimer’s disease. The inhibition of DYRK1A therefore, offers a novel therapeutic approach for the treatment of Alzheimer’s.

The loss of pancreatic β-cell mass is a central feature of both type 1 and type 2 diabetes. Pancreatic β-cells and neuronal cells share many similarities in terms of gene expression and development. Research in both mice and human islet cells in vivo models show that DYRK1A is expressed in pancreatic islets and show that DYRK1A inhibition leads to β-cell proliferation and modulates glycaemia with normalized blood glucose at resting baseline and after a challenge to glucose (Rachdi et al 2014, Shen et al 2015, Wang et al 2015, Rachdi et al 2016, Dirice et al 2016). These studies show the crucial role of the DYRK1A pathway in the regulation of β-cell mass and carbohydrate metabolism and offer considerable promise for diabetes treatment.