Twin studies of schizophrenia: From bow-and-arrow concordances to Star Wars Mx and functional genomics

TLDR

Twin studies have been essential for demonstrating a strong genetic contribution to schizophrenia and for exploring its relationships with other disorders, clinical heterogeneity, and non‑inherited factors through discordant monozygotic pair analyses. Recent twin studies aim to directly investigate the molecular genetic and epigenetic mechanisms underlying schizophrenia. The latest European and Japanese twin studies confirm high heritability of schizophrenia, with monozygotic concordance rates of 41–65 %, dizygotic rates of 0–28 %, and heritability estimates of 80–85 %.

Abstract

Twin studies have been vital for establishing an important genetic contribution to the etiology of schizophrenia. The five newest studies since 1995 from Europe and Japan have confirmed earlier findings. They yielded probandwise concordance rates of 41-65% in monozygotic (MZ) pairs and 0-28% in dizygotic (DZ) pairs, and heritability estimates of approximately 80-85%. Twin studies are also valuable for investigating the etiological relationships between schizophrenia and other disorders, and the genetic basis of clinical heterogeneity within schizophrenia. Studies of discordant MZ pairs provide further insights into non-inherited factors that contribute to the multifactorial etiology of this disorder. More recently, twin studies have begun to be used to directly investigate molecular genetic and epigenetic processes underlying schizophrenia.