Failure to replicate an association between the catechol-O-methyltransferase polymorphism and attention deficit hyperactivity disorder in a second, independently recruited Israeli cohort

Attention deficit hyperactivity disorder (ADHD) is a developmental syndrome expressed along three domains: inattention, hyperactive-impulsive, and combined type. Both environmental and genetic factors contribute to the etiology of this complex disease. We previously reported an association in 48 ADHD triads (both parents and proband) between the catechol-O-methyl- transferase (COMT) polymorphism (especially the high enzyme activity val allele) and the Diagnostic and Statistical Manual of Mental Disorders (DSM IV) combined category (excluding inattention) of ADHD (however, see erratum, Am. J. Med. Genet. [Neuropsychiatr. Genet.] 96:893). In the current report, we attempted to replicate this finding in an independently recruited group of 70 nuclear families using the haplotype relative risk design. In the current investigation, no evidence for association of the COMT polymorphism and ADHD (or any of the DSM IV subtypes) was observed in either the current cohort or the expanded cohort of 118 Israeli triads. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:858-860, 2000.

Interaktionseffekte Monoamin-relevanter genetischer Polymorphismen mit Traits des TPQ

Zusammenfassung: Fortschritte in der Molekulargenetik ermöglichen es, den Erklärungsbeitrag genetischer Polymorphismen mit funktioneller Relevanz zum genetischen Hintergrund der Erblichkeitskomponente einiger Persönlichkeitstraits zu untersuchen. Bisherige Befunde sprechen für potentielle Assoziationen eines Polymorphismus im Dopamin-D4-Rezeptor-Gen (DRD4 Exon 3) mit der Dimension Novelty Seeking (NS) des Tridimensional Personality Questionnaire (TPQ) sowie eines Polymorphismus des Serotonin-Transporter-Gens (5-HTTLPR) mit TPQ Harm Avoidance (HA). Die Betrachtung von Interaktionen dieser Polymorphismen kann einen Beitrag zur Klärung von Inkonsistenzen in bisherigen Assoziationsstudien leisten. In der vorliegenden Arbeit wurden für 134 Personen Interaktionen von DRD4 Exon 3 und 5-HTTLPR sowie einem Polymorphismus des Gens für COMT auf die Faktorwerte der TPQ-Subskalen überprüft. Es zeigten sich Tendenzen zu Interaktionen zwischen DRD4 Exon 3 und 5-HTTLPR bei dem HA-Faktor sowie zwischen DRD4 Exon 3 und dem COMT-Polymorphismus bei dem NS-Faktor.

Hypescheme: an operational criteria checklist and minimum data set for molecular genetic studies of attention deficit and hyperactivity disorders

Investigators engaged in mapping the genetic basis of attention deficit hyperactivity disorder (ADHD) currently use a number of measures for the collection of clinical information. This gives rise to difficulties in comparing datasets and research communications between independent groups. This paper describes the development of Hypescheme, which is an operational criteria checklist for ADHD, oppositional defiant disorder (ODD), and conduct disorder (CD), and is proposed as a minimum dataset for those engaged in molecular genetic studies of ADHD. Hypescheme consists of a computerised data checklist system that includes all the operational criteria required for both DSM-IV and ICD-10 diagnostic criteria and a systematic record of information about comorbid psychiatric, developmental, and neurological disorders. Using this data, an algorithm applies both DSM-IV and ICD-10 criteria to generate operational diagnostics under both these systems. Hypescheme is not designed to replace current assessment protocols but to be a final common checklist that can be completed by experienced researchers using all available data.

No association between low- and high-activity catecholamine-methyl-transferase (COMT) and attention deficit hyperactivity disorder (ADHD) in a sample of Turkish children

Biochemical and genetic studies of attention deficit hyperactivity disorder (ADHD) suggest that regulation of catecholamine neurotransmission is a key factor in the aetiology of the disorder. In particular, it is postulated that an underactive dopamine system is associated with the disorder. In this study we have tested this hypothesis by screening a clinical sample of Turkish children with the combined subtype of ADHD with a functional variant of catecholamine-methyl-transferase (COMT) that codes for high- and low-activity variants of the enzyme. Using within-family tests of association and linkage in a sample of 72 children, we found no evidence for a genetic association or linkage. We conclude that altered regulation of catecholamines due to this polymorphism does not have a significant main effect on the risk for ADHD in this population. However, it remains feasible that more minor effects or interacting effects with other genes or environment exist.

Genetic influences on attention deficit hyperactivity disorder

In this article we review behavioral and molecular genetics studies of attention deficit hyperactivity disorder (ADHD). Family, twin, and adoption studies, along with segregation analyses and molecular genetic studies, all support the hypothesis that both genetic and environmental factors contribute to the etiology of ADHD. Despite this strong evidence for the familial transmission of ADHD, the mode of transmission requires further clarification. In addition, because ADHD appears to be genetically heterogeneous, more work is needed to delineate genetically homogeneous subtypes and describe the range of expression of their underlying genotypes.

Association between tridimensional personality questionnaire (TPQ) traits and three functional polymorphisms: dopamine receptor D4 (DRD4), serotonin transporter promoter region (5-HTTLPR) and catechol O-methyltransferase (COMT)

Dopamine D4 receptor (DRD4), serotonin transporter promoter regulatory region (5-HTTLPR) and catechol O-methyltransferase (COMT) polymorphisms were examined for association with TPQ personality factors in 455 subjects. Significant interactions were observed by multivariate analysis, (COMT x 5-HTTLPR: Hotelling's Trace = 2.3, P = 0.02) and by subsequent univariate 3-way ANOVA when Novelty Seeking (NS) was the dependent variable: 5-HTTLPR x D4DR (F = 6.18, P = 0.03) and COMT x 5-HTTLPR (F = 4.42, P = 0.03). In the absence of the short 5-HTTLPR allele and in the presence of the high enzyme activity COMT val/val genotype, NS scores are higher in the presence of the DRD4 seven-repeat allele. The effect of these three polymorphisms on NS was also examined using a within-families design. Siblings who shared identical genotype groups for all three polymorphisms (COMT, DRD4 and 5-HTTLPR) had significantly correlated NS scores (intraclass coefficient = 0.39, F = 2.26, P = 0.008, n = 49) whereas sibs with dissimilar genotypes in at least one polymorphism showed no significant correlation for NS scores (intraclass coefficient = 0.177, F = 1.43, P = 0.09, n = 110). Similar interactions were also observed between these three polymorphisms and Novelty Seeking when the 150 independently recruited and non-related subjects were analyzed. The current results are consistent with two earlier reports in which we demonstrated an interaction between the 5-HTTLPR and DRD4 polymorphisms in 2-week-old neonates, in the same children assessed again at 2 months of age and in adults. Molecular Psychiatry (2000) 5, 96-100.