Attention Deficit Hyperactivity Disorder and dopamine D4 receptor (DRD4) polymorphisms in South Indian population

Abstract

Objectives Four decades of research have found that Dopamine D4 Receptor (DRD4) is the major candidate gene however, few studies have supported the association between the DRD4 exon III long seven repeat allele and Attention Deficit Hyperactive Disorder (ADHD). Two Indian studies had shown there is an association between DRD4 7 repeat allele; hence, we investigated in the south Indian population. AIMS: To study the association of DRD4-EXON-3-7R long allele and minor physical anomalies with ADHD in comparison to age & sex-controlled normal subjects with no evidence of ADHD. settings and design-cross-sectional case-control study for two years at National Institute of Mental Health And NeuroSciences, Bangalore. Material and Methods 60 children with ADHD and 60 healthy children of 4-16 years of age group were recruited after informed consent. Assessed by DSMIV-TR, ADHD RS IV HOME VERSION 18 items, comorbidities by detailed interview of child and parents using Mini-International Neuropsychiatric Interview for Children & Adolescents (M.I.N.I). Kid for minor congenital anomalies modified waldrop scale & for the perinatal complications, Lewis Murray Obstetrics Complication Scales were applied. For the family history family interview for genetic study, global functioning was measured by children global assessment scale, neuropsychological tests of response inhibition test were used and blood samples was collected for genotyping. Results The genotype 2 2,2 4 ,4 4,4 5,4 7 repeat allele has shown equal distribution between cases and controls with p-value 0.492 with no significance. Conclusion There is no association between DRD4 EXON-3-7R long allele gene polymorphism and ADHD in South Indian population. DRD4 7R could be having influence on minor physical anomalies in ADHD.