Frequencies of obesity susceptibility alleles among ethnically and racially diverse bariatric patient populations

Background: Genetic factors likely play a role in obesity and the outcomes after bariatric surgery. Single nucleotide polymorphisms in or near the insulin-induced gene 2 (INSIG-2), fat mass and obesity-associated gene (FTO), melanocortin 4 receptor gene (MC4R), and proprotein convertase subtilisn/kexin type 1 gene (PCSK-1) have been associated with class III obesity in whites. Minimal data are available regarding the genetic susceptibility to obesity in class III obese nonwhites, especially Hispanics. Our objective was to perform a comparative analysis of 4 common genetic variants (INSIG-2, FTO, MC4R, and PCSK-1) associated with obesity in a diverse population of bariatric surgery patients to determine whether a difference exists by ethnicity (white versus Hispanic). The setting of the study was 2 university hospitals in the United States. Methods: Bariatric surgery patients from 2 different institutions were enrolled prospectively, and genotyping was performed. Differences in the distribution of INSIG-2, FTO, MC4R, and PCSK-1 single nucleotide polymorphisms among the different ethnicities (whites and Hispanics) were compared using an additive model (0, 1, or 2 risk alleles). A propensity-matched analysis was used to account for cohort differences. Results: A total of 1276 bariatric patients were genotyped for the INSIG-2, FTO, MC4R, and PCSK-1 obesity single nucleotide polymorphisms. Statistically significant differences in FTO, INSIG-2, MC4R, and PCSK-1 were seen using an additive model. FTO, PCSK-1, and MC4R (test for trend) remained significantly different in the propensity analysis. Conclusion: Significant differences in the frequencies of several common obesity susceptibility variants in or near FTO, PCSK-1, and MC4R were found in white and Hispanic patients with class III obesity undergoing bariatric surgery. Larger studies in more class III obese Hispanics of different nationalities are needed.