COMT and schizophrenia: Candidate genes of relevance to dopaminergic neurotransmission with risk-alleles that are also considered in the ethiopathogenesis of schizophrenia that have also been associated with schizotypy are primarily the Val158Met-polymorphism (rs4680; Lachman et al., 1996) of the COMT-gene (encoding for the catecholamine-degrading enzyme catechol-O-methyltransferase, COMT) and the variable number of tandem repeats (VNTR)-polymorphism (Vandenbergh et al., 1992) of the SLC6A3-gene (encodes for the dopamine active transporter, DAT).