In addition, complement component C3 has been implicated in metabolic syndrome in schizophrenia patients treated with clozapine (reviewed in Woo et al., 2019) Genes coding for other members in the complement systems that have been associated with schizophrenia susceptibility (Schizophrenia Working Group of the Psychiatric Genomics Consortium, 2014), including the CUB and Sushi multiple domains 1 (CSMD1), C2, and Complement Factor B (CFB), may be an avenue for future genetic investigations of the complement system in TD. This evidence concerns the gene C2 and metabolic syndrome.