Dopamine receptor D4 (DRD4) gene polymorphism among Gaddi tribe of Himachal Pradesh

Abstract

Dopamine is one of the most important neurotransmitters in the brain. D4 receptor of dopamine shows the largest number of polymorphisms among all the dopamine receptors and is one of the most polymorphic of all the genes studied (Chang et al. 1996). DRD4 gene is reported to be associated with personality associated traits like novelty-seeking. The polymorphism in DRD4 is revealed in the variable number of imperfect 48 bp tandem repeats in exon 3, ranging from two to 11 repeat units, with over 67 different haplotype variants (Ding et al. 2002; Grady et al. 2003). In most geographical locations, the 4R allele is the most common, whereas 2R and 7R allele frequencies vary widely (Chang et al. 1996; Ding et al. 2002). The 4R and 7R repeats are the most common worldwide (Chang et al. 1996). 4R and 2R alleles are common in Indian subcontinent (Chen et al.1999). 7R is absent among most of the Indian tribes and rare among caste groups of India. (Saraswathy et al. 2013). This study is an attempt to find out the distribution of DRD4 variants among Gaddis, a transhumant population of northern India. Transhumance is seasonal and short term (for 2–4 months) micro-migration with livestock due to unfavourable change in environment.