RCAN1 and Alzheimer disease: Indeed, animal studies have shown that age-dependent dysregulation of RCAN1, an Hsa21 gene, affects periodicity of the circadian clock, photic entrainment of locomotor patterns, rest-activity profiles, and rhythmicity of activity (Wong and others 2022); it has also been suggested that overexpression of RCAN1 contributes to the early-age onset of AD-linked pathology in DS (Wong and others 2015, 2022).