Investigation of glucocorticoid polymorphisms within a college sample in relation to depression, obesity, and the general population

The stress hormone cortisol has been linked to increased risk of obesity and depression. Certain polymorphisms linked to cortisol sensitivity and production have been hypothesized to be genetic markers of obesity and depression. The goal of our study was to determine if a college population is representative of the general population in terms of allelic frequency. Subsequently, we would use this data to find a correlation between polymorphisms in the glucocorticoid receptor gene and clinical depression/obesity. Our primary hypothesis was that a college population has the same allelic frequency of the specified polymorphisms as that of the general population, and the results produced by a college sample can be generalized to the population. Furthermore, given this first hypothesis, we predicted that there would be a correlation between the presence of mutant genotypes and the diagnoses of clinical depression or obesity in this college population. We took approximately 50 (blind) DNA samples from several students. These samples were then analyzed by polymerase chain reactions (PCR). Some of the polymorphisms that we sampled aligned reasonably well with the general population but not well enough to conclude. For instance, BclI, a GR regulation SNP, produced a mutant proportion of ~0.36 in our student sample, while the general population proportion was estimated to be 0.2546. However, when we ran these proportions through a 1-proportion Z-test, the p-value found was greater than 0.05, meaning that we could not definitively generalize our results to the general population. The other polymorphisms produced varying results that were similarly inconclusive. This study is important in finding possible identifiers for increased risk of obesity and depression. However, further studies with larger samples will still need to be completed to determine whether college populations - particularly Union’s - can serve as an appropriate representation of the general population with regards to GR gene allelic frequencies before the next step can be taken to find correlations with depression and obesity.