LEP and hypothyroidism: The etiology of obesity in youth with DS is unclear (11); however, currently available evidence suggests that a combination of physiologic factors such as increased leptin, decreased resting energy expenditure, chronotropic incompetence and hypotonia, lifestyle factors including consumption of a high calorie diet and low levels of physical activity, and comorbidities associated with DS, including hypothyroidism and congenital heart defects, likely play an important role (6).