(1) Trofinetide’s FDA approval for Rett syndrome (MECP2 mutations causing transcriptional dysregulation and synaptic dysfunction) does not predict efficacy for Alzheimer’s disease pathogenesis involving fundamentally distinct mechanisms (amyloid cascade, tauopathy, neuroinflammation, synaptic loss). The gene discussed is MECP2; the disease is early-onset autosomal dominant Alzheimer disease.