title: The association between the catechol-O-methyltransferase Val108/158Met polymorphism and hyperactive-impulsive and inattentive symptoms in youth.
abstract: BACKGROUND
  Hyperactivity, impulsivity, and inattention are major symptoms occurring in attention-deficit/hyperactivity disorder. This disorder is highly heritable, multifactorial, polygenic, and associated primarily with dysfunctions of dopaminergic, noradrenergic, and serotonergic systems.
  
  
  OBJECTIVE
  The present study tested the possible association of the catechol-O-methyltransferase (COMT) Val108/158Met (rs4680) polymorphism with hyperactive-impulsive and inattentive symptoms in male youth.
  
  
  METHODS
  Polymorphism COMT Val108/158Met was analyzed in 807 male unrelated Caucasian young subjects: 231 healthy controls, 195 subjects with moderate hyperactive symptoms and 254 subjects with moderate inattentive symptoms, 111 subjects with severe hyperactive symptoms and 90 subjects with severe inattentive symptoms, all evaluated using Swanson, Nolan, and Pelham Questionnaire IV criteria.
  
  
  RESULTS
  The frequency of the COMT genotypes, alleles, and the homozygous Met/Met genotype versus Val carriers (χ²) test with standardized residuals) differed significantly between subjects without and subjects with hyperactive-impulsive and inattentive symptoms. In addition, significantly higher hyperactive-impulsive and inattentive scores were found in subjects with the Met/Met genotype compared to carriers of other COMT genotypes. These significant results were due to the more frequent occurrence of Met/Met genotype or the Met allele in subjects with moderate and severe hyperactive-impulsive and inattentive symptoms compared to matched controls.
  
  
  CONCLUSIONS
  These results suggest that the Met/Met genotype or the Met allele of the COMT Val108/158Met, contributing to higher dopaminergic activity, are significantly overrepresented in subjects with moderate or severe hyperactive-impulsive and inattentive symptoms, and that this polymorphism is significantly associated with hyperactive-impulsive and inattentive symptoms in young boys and adolescents.
authors.affiliation: Division of Molecular Medicine, Rudjer Boskovic Institute, PO Box 180, HR-10002, Zagreb, Croatia.
authors.forename: Matea
authors.initials: M
authors.lastname: Nikolac Perkovic
authors.forename: Evelyn
authors.initials: E
authors.lastname: Kiive
authors.forename: Gordana
authors.initials: G
authors.lastname: Nedic Erjavec
authors.forename: Toomas
authors.initials: T
authors.lastname: Veidebaum
authors.forename: Mario
authors.initials: M
authors.lastname: Curkovic
authors.forename: Katarina
authors.initials: K
authors.lastname: Dodig-Curkovic
authors.forename: Dorotea
authors.initials: D
authors.lastname: Muck-Seler
authors.forename: Jaanus
authors.initials: J
authors.lastname: Harro
authors.forename: Nela
authors.initials: N
authors.lastname: Pivac
mesh_terms: D000293:Adolescent; D000483:Alleles; D001289:Attention Deficit Disorder with Hyperactivity / Q000235:genetics / Q000503:physiopathology*; D016022:Case-Control Studies; D002394:Catechol O-Methyltransferase / Q000235:genetics*; D002648:Child; D004298:Dopamine / Q000378:metabolism; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D007175:Impulsive Behavior / Q000235:genetics / Q000503:physiopathology*; D008297:Male; D020641:Polymorphism, Single Nucleotide; D011594:Psychometrics; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D044465:White People / Q000235:genetics
chemical_list: D002394:Catechol O-Methyltransferase; D004298:Dopamine