DYRK1A and Alzheimer disease: Hsa21 also encodes genes involved in post-translational histone modification, including DYRK1A, ETS2, HMGN1, BRWD1, and RUNX1 (Dekker et al., 2014), which may be investigated for their potential roles leading to the aberrant histone modifications observed in AD (Zhang et al., 2012a; Narayan et al., 2015).