38% of the autoantibodies in patients in our case series are membrane-surface autoantibodies, which suggests that both these membrane-surface (such as CASPR2, KCNA2 and myelin antibodies in our cohort) and CSF intracellular autoantibodies (such as Yo, Zic 4, GAD65 antibodies in our cohort) might play a role in cognitive impairment when the CSF indicates AD pathology. This evidence concerns the gene KCNA2 and Alzheimer disease.