SLC9A6 and Alzheimer disease: Since loss-of-function mutations of NHE6 are implicated in various neurodevelopmental, neuropsychiatric and neurodegenerative diseases including autism spectrum disorder (ASD), Christianson syndrome, X-linked intellectual disability, and Alzheimer’s disease, the regulation of NHE6 function and trafficking is critical for underpinning neurophysiological basis of these diseases [1, 6–10].