Schizophrenia is a mental disorder often presented in patients by abnormal thought processes, impaired emotional responses, and negative symptoms. As a chronic disorder that affects ~1% of all people, schizophrenia can be have debilitating effects on patients, especially on their social lives. Due to the lack of knowledge on its pathophysiology and also the heterogeneity of the symptoms, it has been increasingly important to understand the genetics of schizophrenia.
Due to the marked reduction in fecundity seen in schizophrenic patients, the high heritability of the disorder pointed to the possibility that genetic alleles that were risk factors might occur as de novo mutations. Previous exome sequencing studies showed no promising results, but the inconclusive results were likely due to small sample size and a narrow focus on target genes. Two recent studies, the largest of their kind, gathered data from nearly 7000 people (nearly 3500 patients) from Sweden and Bulgaria, and showed that genetic effects on schizophrenia seemed to be very complex. Specifically, both papers published in Nature reflected on the implication of genetic mutations in clusters of specific proteins that governed signaling networks dealing with learning and memory. The studies identified the presence of de novo mutations, often nonsense mutations, notably in genes related to the PSD (post-synaptic density of dendrites), the calcium channels, the postsynaptic ARC complex, and the NMDA receptors.