In humans, the lower levels of paraoxonase 1 enzyme (PON1) activity in schizophrenia, leading to impaired function of the innate immune system and increased oxidative stress, has been linked to increased IgA responses to Pseudomonas putida, Morganella morganii, and Pseudomonas aeruginosa [162]. This evidence concerns the gene PON1 and schizophrenia.