Reduced DYRK1A expression, truncations, or deletions, such as in DYRK1A haploinsufficiency syndrome/DYRK1A‐related intellectual disability syndrome, are characterised by intellectual disability, developmental and learning disruption and delay, microcephaly, autism spectrum, epileptic seizures, speech delay, and feeding difficulties [209, 265, 266, 267]. The gene discussed is DYRK1A; the disease is Down syndrome.