McCune Albright Disorder (MAS) is a rare mosaic disorder with a broad clinical spectrum. It was first described in 1963 and has a prevalence of 1/1,00,000. It involves multiple systems, making its diagnosis and management a challenging task for clinicians. It represents a classic clinical triad as shown in Figure 1 Etiopathogenesis: Genetic level: Mutations on GNAS gene located on chromosome 20q13.3. These mutations occur at exon-8: Arginine 201 is converted either into histidine (R201H) or cystine (R201C).
Arginine 201 is an important component of GTPase and the most common site for mutation. Phenotype is determined by the extent and location of mutation-bearing tissues. Mutation takes place during the early stages of embryo development. It occurs in all ethnic groups. Cellular and molecular level: Clinical features: Differential diagnosis: Tuberous sclerosis Legius syndrome…
