catechol-O-methyltransferase Val158Met Gene Polymorphism Research Articles

Molecular heterosis in metamphetamine abusers

Objective. The aim of our study was to assess whether the catechol-O-methyltransferase (COMT) genetic background of patients dependent on metamphetamine is related to their non-abstinence in a 1-year follow-up. Methods. We examined COMT gene Val158Met polymorphism and 1-year abstinence in a group of 31 (women N=8) Czech Caucasian metamphetamine abusers (average age, 23.8±4.0years). Results. Non-abstinence was significantly (P=0.046, Fisher's exact test) associated with the heterozygous Val/Met genotype. Conclusion. The case where subjects heterozygous for a specific genetic polymorphism show a significantly greater or lesser effect for a phenotypic trait than subjects homozygous for either allele is described as molecular heterosis in the literature. We discuss several explanations and recommendations for further research.

Association study of COMT gene Val158Met polymorphism with auditory P300 and performance on neurocognitive tests in patients with schizophrenia and their relatives

A number of studies have reported an association between catechol-O-methyltransferase (COMT) gene Val158Met polymorphism and neuropsychological traits in patients with schizophrenia, their relatives and healthy controls, with the Met allele carriers performing better on neurocognitive tasks than those with the Val allele. But the association was not confirmed in all studies. The present paper was aimed at further investigation of the COMT gene relationship with some neurocognitive traits, assessing mainly working and verbal memory, and to P300 event-related potentials (auditory oddball). A total sample of 319 individuals, including schizophrenic patients, their relatives and controls, was studied. No significant differences in performance of neurocognitive tasks were found by Val158Met genotypes. An association was observed between the Met/Met genotype and higher amplitude in centro-parietal area in relatives. Factors that could explain the non-replication of previous studies on the COMT gene polymorphism and neurocognitive traits are discussed. We suggest here that (1) Val158Met polymorphism rather exerts a modifying influence on brain activation in general than impacts directly on performance of the particular neurocognitive test, and (2) P300 amplitude seems to be a correlate of this activation reflecting, along with information processing, the subject's affective and personality features.

COMT Val 158Met polymorphism in schizophrenia with obsessive-compulsive disorder: A case–control study

This is the first study of a possible molecular genetic basis for schizophrenia with obsessive-compulsive disorder (OCD). We performed a case–control association study of the catechol- O-methyltransferase (COMT) Val 158Met polymorphism in schizophrenia–OCD patients, OCD and healthy controls. One hundred and thirteen schizophrenia–OCD patients, 79 OCD patients and 171 control subjects were genotyped for the Val 158Met polymorphism in the COMT gene. There was no significant difference in allele and genotype distribution of the COMT gene between schizophrenia–OCD patients and healthy controls. The low-activity Met allele and Met/Met genotype were more frequent in OCD men than in schizophrenia–OCD and control individuals. This difference, however, was not statistically significant following correction for multiple comparisons. These results do not support the hypothesis that the COMT Val 158Met gene polymorphism is associated with liability to schizophrenia–OCD.

COMT (Val158Met) polymorphism is not associated to neuropathic pain in a Spanish population

It is well known that the response to painful stimuli varies between individuals and this could be consequence of individual differences to pain sensitivity that may be related to genetic factors. Catechol- O-methyltransferase (COMT) is one of the enzymes that metabolize catecholamine neurotransmitters. Differences in the activity of COMT influence the functions of these neurotransmitters. A single nucleotide polymorphism (Val158Met) of COMT leads to a three to four fold reduction in the activity of the enzyme and has been associated to modifications in the response to a pain stressor. Neuropathic pain is a progressive nervous system disease due to an alteration of the peripheral or central nervous system. To elucidate the possible role of COMT polymorphism in the susceptibility to neuropathic pain, we have performed a case–control study in a Spanish population. Analysis of the (Val158Met) COMT polymorphism was performed by PCR amplification and DNA digestion with restriction enzymes. Our study concludes that functional Val158Met polymorphism of COMT gene is not associated to increased susceptibility to neuropathic pain.