Does Genetic Predisposition Influence Surgical Results of Operations for Obesity?

BACKGROUND: There is a familial predisposition to obesity. We wished to document the incidence of obesity (BMI > 40 kg m(2)) in the immediate relatives (parents and siblings) of obese patients who were candidates for gastric restrictive surgery. We determined if a familial predisposition to obesity would influence the surgical results. METHODS: The height, weight and BMI were obtained in 1841 relatives of obese patients and in 1059 relatives of normal weight controls. The results of gastric surgery after 52.9 +/- 23.1 months were obtained in 44 patients with a familial history of obesity and in 34 patients without a familial history. RESULTS: Patients presenting with a BMI > 40 kg m(2) were 24.541 times more likely to have a first degree relative with morbid or super obesity than individuals in the control group. Mothers were twice as likely to be severely obese as fathers. A successful result (BMI < 35 kg m(2) or less than 50% excess weight) occurred 52.9 +/- 23.1 months in 77% of patients with a family history of obesity.and in 73% of patients without a familial predisposition (p = 0.79). CONCLUSIONS: There is a strong familial predisposition to obesity but over one-half of the immediate family members of obese patients have a BMI < 30 kg m(2). Gastric restrictive surgery induces satiety and produces a successful outcome regardless of familial predisposition. Patients who undergo surgery have a remarkably stable weight over the year prior to operation, suggesting they are defending a markedly elevated BMI.