title: The association of the dopamine D4 receptor gene (DRD4) and the serotonin transporter promoter gene (5-HTTLPR) with temperament in 12-month-old infants.
abstract: This study examined the association between two common polymorphisms, the dopamine D4 receptor (DRD4) gene and the serotonin transporter promoter (5-HTTLPR) gene and temperament in 61 infants aged 12 months. Twenty-two infants had a least one copy of the 6-8 repeat DRD4 alleles (L-DRD4) and 39 had two copies of the 2-5 repeat allele (S-DRD4). Twenty infants were homozygous for the short form (s/s) of 5-HTTLPR while 41 were either heterozygous for the short and the long form (l/s) or were homozygous for the long form (l/l). The infants were observed in a series of standard temperament episodes that elicited fear, anger, pleasure, interest, and activity. L-DRD4 infants showed less interest in a structured block play situation and more activity in a free play situation. They also displayed less anger in an episode of mild physical restraint. Infants with s/s 5-HTTLPR showed less fearful distress to stranger approach and less pleasure in a structured play situation than infants with l/l or l/s 5-HTTLPR. Duration of looking during block play was affected by a significant interaction between DRD4 and 5-HTTLPR. Shortest duration of looking was associated with the L-DRD4 and s/s 5-HTTLPR genotypes. The implications and limitations of these findings are discussed.
authors.affiliation: Department of Behavioral Sciences, Ben-Gurion University, Beer Sheva, Israel. judy@bgumail.bgu.ac.il
authors.forename: J G
authors.initials: JG
authors.lastname: Auerbach
authors.forename: M
authors.initials: M
authors.lastname: Faroy
authors.forename: R
authors.initials: R
authors.lastname: Ebstein
authors.forename: M
authors.initials: M
authors.lastname: Kahana
authors.forename: J
authors.initials: J
authors.lastname: Levine
mesh_terms: D000786:Anger; D002352:Carrier Proteins / Q000235:genetics*; D005239:Fear; D005260:Female; D006801:Humans; D007223:Infant; D018730:Infant Behavior; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics*; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D017448:Receptors, Dopamine D2 / Q000235:genetics*; D050638:Receptors, Dopamine D4; D012494:Sampling Studies; D012701:Serotonin / Q000378:metabolism*; D050486:Serotonin Plasma Membrane Transport Proteins; D013694:Temperament
chemical_list: D002352:Carrier Proteins; C493599:DRD4 protein, human; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D017448:Receptors, Dopamine D2; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; D050638:Receptors, Dopamine D4; D012701:Serotonin