Abstract
Psychiatric disorders are complex and common diseases that display familial aggregation, multifactorial inheritance, and clinical and genetic heterogeneity. Cognitive functions, brain structures, and personality traits are useful intermediate phenotypes to reduce these heterogeneity. Because genetic factors are involved in the disorders of intermediate phenotypes as well as in psychiatric disorders, it is assumed that there is a common genetic basis between psychiatric disorders and intermediate phenotypes. Large‐scale genome‐wide association studies (GWAS) have been conducted for various psychiatric disorders and intermediate phenotypes, and many related genomic loci have been identified. In contrast to GWAS, which attempt to identify more strongly related genomic loci, polygenic risk score and LD score regression analyses use genome‐wide genetic polymorphism information to examine the common genetic basis between psychiatric disorders and between psychiatric disorders and intermediate phenotypes. In this article, we introduce our studies on the genetic commonalities and disease specificities among psychiatric disorders and between psychiatric disorders and intermediate phenotypes using these analysis techniques.
