This multi‐center retrospective study enrolled 390 participants: 222 definite AE patients (comprising four subtypes: LGI1‐AE, NMDAR‐AE, GABAB‐AE, GAD65‐AE), 122 age‐ and sex‐matched healthy controls, and 33 age‐ and sex‐matched antibody‐negative AE patients along with 13 age‐ and sex‐matched viral encephalitis patients, both serving as disease controls. Here, GAD2 is linked to acrodermatitis enteropathica.