Investigating Genetic Underpinnings of Depression

Current estimates of worldwide depression incidence are over 280 million people, with women and those over 50 at even greater risk. Research has found numerous potential genetic links, including those within the hypothalamic-pituitary-adrenal (HPA) axis, specifically with relation to glucocorticoids, and within the immune system, particularly as it relates to cytokine production and function. Based on this, we have hypothesized that single nucleotide polymorphisms (SNPs) in glucocorticoid receptors (GR) and corticotropin releasing hormone receptor 1 (CRHR1), as well as interleukin 1 (IL-1B) and cyclooxygenase 2 (COX-2) may predict incidence of depression. Our study investigated the genotypic frequency of several SNPs related to both HPA axis and immune system function. Buccal swabs provided DNA and were acquired from both patients being treated from psychiatric illness, and from a control population. Extracted DNA was analyzed using a combination of allele-specific polymerase chain reaction (asPCR), as well as quantitative polymerase chain reaction (qPCR) to determine allelic frequency associated with each SNP. Participants also completed the Center for Epidemiologic Studies Depression Scale (CES-D) and the Mini Mood and Anxiety Symptom Questionnaire (Mini-MASQ). Participant scores on these measurements spanned the range of potential scores, including non-symptomatic, sub-clinical, and clinical. Understanding the connection between depression and genotypic variation can help shape diagnosis and treatment in the future, with the goal of improving patient outcomes.