DYRK1A and Cognitive impairment: In particular, an altered copy number for segments of Hsa21 containing the dual-specificity tyrosine phosphorylated and regulated kinase 1A (DYRK1a) gene can induce morphological defects and cognitive impairments (Delabar et al., 1993; Ronan et al., 2007; van Bon et al., 2011).