We now observe a weak but positive relationship between A2M levels and psychosis risk, in line with previously reported differences between individuals with schizophrenia and controls20 and a prediction model developed in a schizophrenia case-control sample.19 In agreement with a recent study measuring complement proteins with ELISA in individuals with CHR symptoms,42 we observe decreased levels of C5 in individuals that transitioned to psychosis. This evidence concerns the gene C5 and psychotic disorder.