As a psychiatric disorder with onset in adulthood, schizophrenia is thought to be triggered by some combination of environmental factors and genetics, although the exact cause is still not fully understood. Researchers have now found a correlation between schizophrenia and somatic copy-number variants, a type of mutation that occurs early in development but after genetic material is inherited. This study is one of the first to rigorously describe the relationship between somatic — not inherited — genetic mutations and schizophrenia risk.