Obesity and Hyperphagia With Increased Defective ACTH: A Novel POMC Variant

Objective Patients with pro-opiomelanocortin (POMC) defects generally present with early-onset obesity, hyperphagia, hypopigmentation and adrenocorticotropin (ACTH) deficiency. Rodent models suggest that adequate cleavage of ACTH to alpha-melanocortin-stimulating hormone (alpha-MSH) and desacetyl-alpha-melanocortin-stimulating hormone (d-alpha-MSH) by prohormone convertase 2 at the KKRR region is required for regulating food intake and energy balance. Methods We present 2 sisters with a novel POMC gene variant, leading to an ACTH defect at the prohormone convertase 2 cleavage site, and performed functional studies of this variant. Results The patients had obesity, hyperphagia and hypocortisolism, with markerly raised levels of ACTH but unaffected pigmentation. Their ACTH has reduced potency to stimulate the melanocortin (MC) 2 receptor, explaining their hypocortisolism. Conclusion The hyperphagia and obesity support evidence that adequate cleavage of ACTH to alpha-MSH and d-alpha-MSH is also required in humans for feeding control.