Haploinsufficiency of the DYRK1A gene, due to various truncation mutations, microdeletions, or missense variants resulting in reduced DYRK1A, is responsible for MRD7, an autism spectrum disorder displaying microcephaly, intellectual disability, speech impairment, and distinct facies (reviews: [91,102,103,104]). Here, DYRK1A is linked to microcephaly.