PC1/3 deficiency, an autosomal-recessive disorder caused by rare mutations in the PCSK1 gene, whose main clinical manifestation is characterized by malabsorptive diarrhea, polyphagia with obesity, and a series of endocrinopathies, including growth hormone deficiency, adrenal insufficiency, central diabetes insipidus, central hypothyroidism, and hypogonadism (3). Here, PCSK1 is linked to obesity due to melanocortin 4 receptor deficiency.