Cathechol-O-methyltransferase Val 158 Met polymorphism is associated with disruptive behavior disorders among children and adolescents with ADHD

COMT Val/Met and Psychopathic Traits in Children and Adolescents: A Systematic Review and New Evidence of a Developmental Trajectory toward Psychopathy

Psychopathic traits in youth may lead to adult criminal behaviors/psychopathy. The Val158Met polymorphism of catechol-O-methyltransferase (COMT) may influence the risk for psychopathy-related behaviors, while acting as a biomarker for predicting treatment response to dopaminergic medications. The literature shows inconsistent findings, making the interpretation of COMT's role difficult. The aims of this article are (i) to conduct a systematic review to analyze the effects of COMT Val158Met on psychopathic traits in children and adolescents, and (ii) to present new evidence on the developmental trajectory of the association of Val158Met and youth psychopathic traits. For the systematic review, a literature search was conducted using PubMed, EMBASE, OVID Medline and PsychINFO with the search terms for psychopathic traits, Val158Met and age of interest. In our genotype study, the COMT Val158Met genotype of 293 youth with European ancestry was analyzed in association with the psychopathy-related behavior scores from the Child Behavior Checklist and the Psychopathy Screening Device. To examine the potential influence of developmental changes, the sample was split into at or above and below age 13, and analyses were performed in males and females separately. The literature search yielded twenty-eight articles to be included in the systematic review, which demonstrated mixed results on the association depending on environmental factors, sex ratios, age groups and behavioral disorder diagnoses. The results from our genotype study revealed that Met homozygous youth in the below age 13 group and conversely Val carrier youth in the above age 13 group were more likely to display psychopathic traits. To our knowledge, this is the first study to systematically review the effects of COMT Val158Met on psychopathic traits in childhood and adolescence, and to provide new evidence on the changing effects of Val158Met on psychopathy-related behaviors with development. Elucidating the role of the COMT genotype in conjunction with the child versus adolescent stage of development for psychopathic traits may help predict treatment response, and may lead to early intervention and prevention strategies.

Interaction Between Season of Birth and COMT Val158Met (rs4680) in ADHD in a Large Sample of Chinese Han Participants

OBJECTIVE

To investigate the interaction between catechol-O-methyltransferase gene (COMT) Val108/158Met (rs4680) and season of birth (SOB) on ADHD and its symptoms.

METHOD

We conducted transmission disequilibrium tests (TDTs) in 976 trios, then further performed the above analyses in subgroups according to SOB. Quantitative analyses were performed for ADHD symptoms evaluated by ADHD Rating Scale-IV in 1,530 ADHD cases.

RESULTS

Overall, there was no association between COMT and ADHD. After stratification, we found an increased transmission of the Val allele in the trios born in spring, while a decreased transmission was observed in the autumn months. We also observed a significant interaction between Val108/158Met and SOB on ADHD symptoms. Among those born in spring, Met carriers had milder ADHD symptoms compared with Val homozygotes, whereas opposite association was found in those born in autumn.

CONCLUSION

Our study provided evidence for the modifying effect of SOB on the association between COMT and ADHD along with its symptoms.

COMT and DAT1 genes are associated with hyperactivity and inattention traits in the 1993 Pelotas Birth Cohort: evidence of sex-specific combined effect

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) symptoms are dimensionally distributed in the population. This study aimed to assess the role of the catechol-O-methyltransferase (COMT) and of the dopamine transporter (DAT1) genes on ADHD symptoms in the general population.

METHODS

We investigated 4101 individuals from the 1993 Pelotas Birth Cohort Study using the parent version of the Strengths and Difficulties Questionnaire (SDQ) at ages 11 and 15 years. The SDQ hyperactivity/inattention scores were the main outcomes.

RESULTS

Linear regression analyses demonstrated that the increasing number of COMT158Val and DAT1 10R alleles significantly predicted increasing SDQ hyperactivity/inattention scores in boys at both 11 and 15 years of age (β coefficient = 0.049, t = 2.189, p = 0.029, R² = 0.012, and β coefficient = 0.064, t = 2.832, p = 0.005, R² = 0.008, respectively). The presence of both COMT158Val and DAT1 10R alleles was also associated with full categorical ADHD diagnosis at 18 years of age in boys (χ² = 4.561, p = 0.033, odds ratio 2.473, 95% confidence interval 1.048-5.838) from this cohort. We did not observe these associations in girls.

LIMITATIONS

Our analyses of SDQ hyperactivity/inattention scores were not corrected for SDQ scores of conduct problems because these variables were highly correlated.

CONCLUSION

This study demonstrates a role for COMT and DAT1 genes on hyperactivity/inattention symptoms and provides further support for ADHD as the extreme of traits that vary in the population. It also confirms previous evidence for sexual dimorphism on COMT and DAT1 gene expression.

The Role of the Catechol-o-Methyltransferase (COMT) GeneVal158Met in Aggressive Behavior, a Review of Genetic Studies

Aggressive behaviors have become a major public health problem, and early-onset aggression can lead to outcomes such as substance abuse, antisocial personality disorder among other issues. In recent years, there has been an increase in research in the molecular and genetic underpinnings of aggressive behavior, and one of the candidate genes codes for the catechol-O-methyltransferase (COMT). COMT is involved in catabolizing catecholamines such as dopamine. These neurotransmitters appear to be involved in regulating mood which can contribute to aggression. The most common gene variant studied in the COMT gene is the Valine (Val) to Methionine (Met) substitution at codon 158. We will be reviewing the current literature on this gene variant in aggressive behavior.

COMT and prenatal maternal smoking in associations with conduct problems and crime: the Pelotas 1993 birth cohort study

Conduct problems in childhood and adolescence are significant precursors of crime and violence in young adulthood. The purpose of the current study is to test the interaction between prenatal maternal smoking and COMT Val(158)Met in conduct problems and crime in the 1993 Pelotas Birth Cohort Study. Conduct problems were assessed through the parent version of the Strengths and Difficulties Questionnaire at ages 11 and 15 years. A translated version of a confidential self-report questionnaire was used to collect criminal data at 18 years of age. Negative binomial regression analyses showed an association between prenatal maternal smoking and SDQ conduct problem scores (IRR = 1.24; 95% CI: 1.14-1.34; p < 0.001) at 11 years of age. However, no evidence was found for an association between COMT genotypes and conduct scores or for an interaction between maternal smoking and this gene in predicting conduct problems. Very similar results were obtained using the 15 years conduct scores and crime measure at age 18. Prenatal maternal smoking was associated with crime (IRR = 1.28; 95% CI: 1.09-1.48; p = 0.002) but neither COMT genotypes nor the possible interaction between gene and maternal smoking were significantly associated with crime. Replications of GxE findings across different social contexts are critical for testing the robustness of findings.

Identifying mechanisms that underlie links between COMT genotype and aggression in male adolescents with ADHD

BACKGROUND

There is a known strong genetic contribution to aggression in those with ADHD. In a previous investigation of a large population cohort, impaired 'emotional/social cognitive' processing, assessed by questionnaire, was observed to mediate the link between COMT Val158Met and aggression in individuals with ADHD. We set out to replicate and extend this finding in a clinical sample, using task-based and physiological assessments of emotional and cognitive processing. Our aim was to test the hypothesis that directly assessed emotional processing mediates the link between COMT Val158Met and aggression in young people with ADHD.

METHODS

Males aged 10-17 years with ADHD were recruited from UK community clinics (n = 194). Research diagnostic interviews (parent and child) were used to assess psychopathology and generate DSM-IV Conduct Disorder symptom scores. Participants completed tasks assessing executive function (response inhibition and set shifting), empathy for fear, sadness and happiness, and fear conditioning [measured using skin conductance responses (SCR) to aversive stimuli].

RESULTS

COMT Val allele carriers showed poorer response inhibition (F = 5.27, p = .02) and set shifting abilities (F = 6.45, p = .01), reduced fear empathy (F = 4.33, p = .04) and reduced autonomic responsiveness (lower SCRs) to the conditioned aversive stimulus (F = 11.74, p = .001). COMT Val158Met did not predict impairments in recognising others' emotions or affective empathy for happiness or sadness. Mediation analysis revealed that impaired fear-related mechanisms indirectly mediated the link between COMT Val158Met and aggression.

CONCLUSION

Our findings suggest fear mechanisms as possible targets for psychological interventions to disrupt links between genetic risk and aggressive outcomes in ADHD. Our findings also reveal the potential of hypothesis-driven approaches for identifying neuropsychological mechanisms that mediate genetic risk effects on behaviour and psychopathology.

Structural correlates of COMT Val158Met polymorphism in childhood ADHD: a voxel-based morphometry study

OBJECTIVES

The Val158-allele of the catechol-O-methyltransferase (COMT) Val158Met (rs4680) functional polymorphism has been identified as a risk factor for antisocial behaviour in attention-deficit/hyperactivity disorder (ADHD). Here, we used voxel-based morphometry to investigate the effects of Val158Met polymorphism on grey matter (GM) volumes in a sample of 7-13-year-old children.

METHODS

MRI and genotype data were obtained for 38 children with combined-type ADHD and 24 typically developing (TD) children. Four regions of interest were identified: striatum, cerebellum, temporal lobe and inferior frontal gyrus (IFG).

RESULTS

When compared to TD children, those with ADHD had a significant decrease of GM volume in the IFG. Volume in this region was negatively correlated with ratings of hyperactivity/impulsivity symptoms. Furthermore, the smaller GM volume in the IFG was attributed to the presence of the Met158-allele, as only children with ADHD carrying a Met158-allele exhibited such decrease in the IFG. Children with ADHD homozygotes for the Val158-allele presented increased GM volume in the caudate nucleus when compared with TD children.

CONCLUSIONS

This study provides the first evidence of a modulation of ADHD-related GM volume alterations by Val158Met in two key regions, possibly mediating the relationship between Val158Met polymorphism and antisocial behaviour in children with ADHD.

The possible involvement of genetic variants of NET1 in the etiology of attention-deficit/hyperactivity disorder comorbid with oppositional defiant disorder

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD) often coexist and shared some genetic influences. Evidence from the existing literature indicated that comorbid with ODD may increase the heterogeneity of ADHD genetics. Our present study sought to investigate the role of norepinephrine transporter gene (NET1) for ADHD comorbid with ODD.

METHODS

Six single nucleotide polymorphisms (SNPs) of NET1 were genotyped for a total of 1,815 ADHD cases, including 587 subjects (32.3%) with ODD. Chi-square tests were conducted for pseudo case-control study comparing allelic and genotypic distributions between ADHD with and without ODD. Among them, there were 1,249 probands together with their parents composing trios for family-based association studies using transmission disequilibrium tests (TDTs). In addition, 1,337 ADHD probands have detailed information of ODD symptoms and were included for quantitative analyses with genotypes using analyses of covariance (ANCOVA). To consider the overlap and correlation of other comorbidities with ODD and eliminate their potential confounding effect, we further repeated above analyses for 'pure ADHD+ODD' versus 'ADHD-only' after excluding other comorbidities except for ODD.

RESULTS

The pseudo case-control study showed different allelic and genotypic distributions of SNP rs3785143 between ADHD with ODD and those without ODD. Family-based association tests indicated overtransmission of the T allele of rs3785143 in ADHD with ODD trios, but no biased transmission in those without ODD. ANCOVA showed association between genotypes of rs3785143 with ODD symptoms in ADHD probands, especially with 'Argumentative/Defiant Behavior (ADB)' dimension after controlling gender, age, clinical subtypes and intelligence. Above association still existed after removing the samples with other comorbidities.

CONCLUSION

NET1 was associated with comorbidity of ODD and ODD symptoms in ADHD probands. Our findings emphasize the importance of considering the comorbidity of ODD in ADHD genetic studies, especially ADHD with ADB. However, further replication in independent sample or different populations is still needed.

Association of genetic risk severity with ADHD clinical characteristics

This study sought to examine the association between the cumulative risk severity conferred by the total number of attention-deficit/hyperactivity disorder (ADHD) risk alleles of the DAT1 3'UTR variable number tandem repeat (VNTR), DRD4 Exon 3 VNTR, and 5-HTTLPR with ADHD characteristics, clinical correlates, and functional outcomes in a pediatric sample. Participants were derived from case-control family studies of boys and girls diagnosed with ADHD, a genetic linkage study of families with children with ADHD, and a family genetic study of pediatric bipolar disorder. Caucasian children 18 and younger with and without ADHD and with available genetic data were included in this analysis (N = 591). The association of genetic risk severity with sociodemographic, clinical characteristics, neuropsychological, emotional, and behavioral correlates was examined in the entire sample, in the sample with ADHD, and in the sample without ADHD, respectively. Greater genetic risk severity was significantly associated with the presence of disruptive behavior disorders in the entire sample and oppositional defiant disorder in participants with ADHD. Greater genetic risk severity was also associated with the absence of anxiety disorders, specifically with the absence of agoraphobia in the context of ADHD. Additionally, one ADHD symptom was significantly associated with greater genetic risk severity. Genetic risk severity is significantly associated with ADHD clinical characteristics and co-morbid disorders, and the nature of these associations may vary on the type (externalizing vs. internalizing) of the disorder.

Genomic disorders on chromosome 22

PURPOSE OF REVIEW

Chromosome 22, the first human chromosome to be completely sequenced, is prone to genomic alterations. Copy-number variants (CNVs) are common because of an enrichment of low-copy repeat sequences that precipitate a high frequency of nonallelic homologous misalignments and unequal recombination during meiosis. Among these is one of the most common multiple anomaly syndromes in humans and the most common microdeletion syndrome, velocardiofacial syndrome (VCFS), also known as 22q11.2 deletion syndrome and DiGeorge syndrome. This review will focus on the recent literature dealing with both the molecular and clinical aspects of chromosome 22 genomic variations. Although the literature covering this area is expansive, the majority is descriptive or analytical of the problems presented by these genomic disorders, and there is little evidence of translational research including treatment outcomes.

RECENT FINDINGS

With the increased use of microarray analysis in both research and clinical practice, variations in CNVs are becoming elucidated. Genomic analysis continues to characterize genes and gene effect. Research on the COMT gene continues to yield interesting findings, including a possible sex-mediated effect because of its regulatory role with estrogen. There is a small amount of treatment outcome data relevant to neuropsychiatric disorders in VCFS, but based on small samples and short-term follow-up.

SUMMARY

Although hundreds of studies in the past year have focused on genomic disorders of chromosome 22, little progress has been made in the implementation of translational research, even for more common disorders including VCFS.