GNAS and polyostotic fibrous dysplasia: <h4>Background</h4>McCune-Albright is a rare syndrome, caused by mutation of the <i>GNAS1</i> gene, and is characterized by an appearance of multiple endocrinopathies, most commonly premature puberty, polyostotic fibrous dysplasia and skin changes called <i>cafe au lait</i> macules.<h4>Case report</h4>We present the case of a patient who is, to the best of our knowledge and after extensive review of literature, the youngest McCune-Albright syndrome patient with growth hormone excess, diagnosed at 8.9 months of age.