DYRK1A and Dravet syndrome: For example, in the Ts65Dn DS mouse model, with about half of the genes homologous to Hsa21 in three copies, increased DYRK1A protein levels in neural stem cells of the cerebellar cortex lengthens the G1 phase and reduce neuronal production, supporting the role of DYRK1A in the development of cognitive phenotypes associated with DS (Najas et al., 2015).