Importantly, using the search terms (schizophrenia) AND (BDNF gene polymorphism) to find articles published in the last 5 years, Farcas et al. conducted a systematic search on Val66Met polymorphism of the BDNF gene and showed that the Met/Met genotype is associated with higher positive scores on the Positive and Negative Syndrome Scale (PANSS), reflecting disease severity, and with a history of suicide attempts [15]. This evidence concerns the gene BDNF and schizophrenia.