Is McCune-Albright syndrome overlooked in subjects with fibrous dysplasia of bone?

Objective: McCune-Albright syndrome (MAS) is characterized by a clinical triad of endocrinopathies, café au lait pigmentation, and polyostotic fibrous dysplasia of bone. We hypothesized that children diagnosed with fibrous dysplasia are not routinely being evaluated for coexisting endocrine dysfunction or MAS. Our objective was to prospectively screen subjects with fibrous dysplasia for endocrine disease and G_sα gene (GNAS1)-activating mutations. Study design: Nine subjects who presented with fibrous dysplasia and were followed in orthopedic clinics were evaluated for other manifestations of MAS. Genomic DNA was isolated from blood, and mutation analysis of GNAS1 was performed. Results: On physical examination, 5 of 9 subjects were found to have café au lait pigmentation. Three of 9 subjects had TSH levels below the normal range. One of these subjects was found to have hyperthyroidism and was treated by total thyroidectomy. GNAS1 mutations were identified in 5 of 9 subjects with either monostotic or polyostotic fibrous dysplasia of bone. Conclusions: We conclude that a substantial proportion of children being followed for fibrous dysplasia of bone have unrecognized clinical and laboratory features of MAS. These children are at risk for endocrinopathy and should be screened accordingly.