Regarding genetics, some authors explored the possibility that polymorphisms of genes involved in the regulation of neurotransmission (e.g., Catechol-O-methyltransferase-COMT) [23] or neuron function (e.g., Neuroregulin 1-NRG1) confer vulnerability to develop psychotic symptoms in BD [24]. This evidence concerns the gene COMT and Behcet disease.