CYFIP2 is a component of the actin regulatory WAVE complex, which binds the fragile X messenger ribonucleoprotein (FMRP) (21–23) and has been implicated in developmental delay, epilepsy, West syndrome (a developmental and epileptic encephalopathy), and Alzheimer’s disease (23–25). Here, FMR1 is linked to early-onset autosomal dominant Alzheimer disease.