Although we did not measure serostatus before the acute event, there are strong arguments supporting the preexistence of serum NMDAR1-abs before the stroke: first, it takes a minimum of 4 days to generate any antibody after antigen presentation,(26) thus titers as measured in our study are unlikely to be observed after such a short time if the antibodies were not preexisting (median day of blood sampling after stroke = 4, IQR: 3–5). The gene discussed is GRIN1; the disease is Stroke.