The acoustic startle response and polymorphism of the gene for catechol-O-methyltransferase in the norm and in schizophrenia

Using 46 healthy subjects and 47 male patients with schizophrenia we studied the influence of the rs4680 polymorphism (Val158Met) in the gene for catechol-O-methyltransferase (COMT), an enzyme that metabolizes catecholamines, on the level of catecholamines in the blood plasma and basic parameters and prepulse inhibition of the acoustic startle response (ASR), which are potential neurophysiological markers of the risk of the development of schizophrenia. An effect of the polymorphism of the COMT gene on the prepulse inhibition of ASR was observed only in healthy persons and consisted in a decrease in this index in carriers of the Val/Val genotype. In patients with schizophrenia, polymorphism of the COMT gene was associated with another potential endophenotype of schizophrenia, viz., the basic latent period of ASR; its largest increase, as compared to the norm, was found in homozygous carriers of Met at the 158th position. We found a positive correlation between prepulse inhibition and the ratio of dopamine metabolism in the blood plasma of healthy subjects and the adrenaline level in patients. Binary logistic regression showed that inclusion of the factor of the genotype considerably increases the validity of the diagnostic model, which is based on the evaluation of the neurophysiological indices.