Sekar et al. reported that complex variations of the complement component 4 (C4) gene may increase the genetic risk of schizophrenia and further explore the potential function contributing to the mechanism of schizophrenia.19 Another study identified a human-specific arsenite methyltransferase (AS3MT) isoform that may be one of the molecular risk factors in the 10q24.32 schizophrenia-associated locus.20 This evidence concerns the gene C4A and schizophrenia.