BEX3 and early-onset autosomal dominant Alzheimer disease: The genes brain expressed X‐Linked 1 (BEX1), brain expressed X‐Linked 3 (BEX3), and Stathmin 1 (STMN1) had been confirmed uniquely down‐regulated in excitatory‐ and inhibitory‐neuron in brain bearing AD according to single‐cell transcriptomic analysis of Alzheimer's disease.23