Obesity Genetics: The Prevalence of DRD2, DAT1 and DBH Genes in the Obese Individual




Davis, Karla R.


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Davis, Karla R., Obesity Genetics: The prevalence of DRD2, DAT1 and DBH Genes in the obese individual. Master of Science (Biomedical Sciences), August, 1998, 106 pp., 3 tables, 14 illustrations, reference, 44 titles. Obesity has been presented in research literature as a polygenic or multiple gene disorder. Currently, 3 genes have been associated with obesity, dopamine receptor D2 (DRD2), dopamine transporter (DAT1), and dopamine beta hydroxylase (DBH). The primary objective of this study is to analyze the DRD2, DAT1 and DBH genes to determine if a correlation exists between certain allelic variations of these 3 genes and the body mass index of obese individuals. We have developed an assay for the DRD2, DAT1 and DBH genes, utilizing polymerase chain reaction (PCR) technology. Within the DRD2 gene, 2 allelic variants have been identified, the A1 and A2 alleles. The A1 allele consists of a 310 bp fragment in which the Taq 1 restriction site has been deleted. The A2 allele consists of 180 bp fragment and a 130 bp fragment. The presence of the A1 allele after enzyme digestion has shown a strong correlation to obesity in prior studies. With respect to the DAT1 gene, a VNTR of 40 bp’s has been correlated to other disorders within the ‘reward deficiency syndrome’. The fragment length identified most often is 440 or 480 bp, with 480 as the primary fragment in obesity. The DBH gene is similar to the DRD2 in that it also contains a Taq I restriction. Two allelic variants are also identified, B1 and B2. The B1 allele contains no Taq I site and produces a 316 bp fragment while the B2 does cleave, exhibiting an 86 bp and a 230 bp fragment after enzyme digestion. The presence of one or more of the aberrant alleles could be associated with and a predisposing factor to obesity.