CYP2E1 and schizophrenia: However, apart from a case-control study of Japanese subjects in 1997 (sample size: 41 cases and 75 controls) with the result that no linkage of the CYP2E1 c1/c2 polymorphism to schizophrenia has been found [21], there has been virtually no comprehensive study of association between genetic polymorphisms of CYP2E1 gene and schizophrenia.