Insertion/deletion polymorphism of the angiotensin-converting enzyme gene is associated with schizophrenia in a Spanish population

A number of factors make the angiotensin-converting enzyme (ACE) a candidate gene for psychiatric disorders, including its action on neurotransmitters such as dopamine. An insertion/deletion (I/D) polymorphism in an ACE gene intron is associated with ACE levels. Here we examine whether the ACE I/D polymorphism is a risk factor for schizophrenia. Participants comprised 243 subjects diagnosed with schizophrenia and related disorders, and 291 hospital-based controls. The D allele of the ACE gene was identified as a protective factor, significantly reducing the risk of developing schizophrenia and related disorders (by 40%) and of developing schizophrenia (by 50%). This protection is explained by the additive genotype risk model, in which the protection increases with the number of D alleles. Our results indicate that the ACE D allele is involved in the development of schizophrenia.