Abstract
IntroductionThe G protein‐coupled receptor kinase interacting protein 1 gene (GIT1) has been proposed to be a risk gene for attention deficit hyperactivity disorder (ADHD), and it regulates the endocytosis of G protein‐coupled receptors like dopamine receptors. The purpose of this study was to investigate the interaction effects of GIT1 and dopamine receptor D4 (DRD4) gene variants on variables of the continuous performance test (CPT).MethodsThis study recruited 255 ADHD patients and 98 healthy controls (HC) who underwent CPT and genetic analyses. The genotypes were classified into two groups (the C/C and C/T genotype groups for GIT1, 4R homozygotes and others for DRD4) and the genotype × genotype effects were examined using hierarchical multivariable linear regression analyses.ResultsThere were significant GIT1 × DRD4 effects for commission errors on the CPT in the ADHD group (p = .006). In contrast, there were no significant GIT1 × DRD4 effects on any CPT variables in the HC.ConclusionsThe present findings demonstrated that there were significant interaction effects of the GIT1 and DRD4 gene variants on impulsivity in ADHD. Replication studies with larger sample sizes that include patients from various ethnic backgrounds are warranted to confirm these findings.
Highlights
The G protein-coupled receptor kinase interacting protein 1 gene (GIT1) has been proposed to be a risk gene for attention deficit hyperactivity disorder (ADHD), and it regulates the endocytosis of G protein-coupled receptors like dopamine receptors
A majority of studies investigating ADHD have focused on catecholamine dysregulation and dopamine-related genes that are related to attentional processes (Gizer, Ficks, & Waldman, 2009), copy number variation and genome-wide association studies (GWAS)
Post hoc analyses revealed that the dopamine receptor D4 (DRD4) variants were significantly associated with continuous performance test (CPT) variables in the GIT1 C/T group but not in the GIT1 C/C group
Summary
The G protein-coupled receptor kinase interacting protein 1 gene (GIT1) has been proposed to be a risk gene for attention deficit hyperactivity disorder (ADHD), and it regulates the endocytosis of G protein-coupled receptors like dopamine receptors. The purpose of this study was to investigate the interaction effects of GIT1 and dopamine receptor D4 (DRD4) gene variants on variables of the continuous performance test (CPT). A majority of studies investigating ADHD have focused on catecholamine dysregulation and dopamine-related genes (e.g., dopamine receptor D4 [DRD4]) that are related to attentional processes (Gizer, Ficks, & Waldman, 2009), copy number variation and genome-wide association studies (GWAS). As different genetic backgrounds are associated with different allele frequencies and risks for diseases, the interpretation of these findings is difficult
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