McCune-Albright syndrome: a detailed pathological and genetic analysis of disease effects in an adult patient.

CONTEXT: McCune Albright syndrome (MAS) is a clinical association of endocrine and nonendocrine anomalies caused by postzygotic mutation of the GNAS1 gene, leading to somatic activation of the stimulatory α-subunit of G protein (Gsα). Important advances have been made recently in describing pathological characteristics of many MAS-affected tissues, particularly pituitary, testicular, and adrenal disease. Other rarer disease related features are emerging.

OBJECTIVE

The objective of the investigation was to study the pathological and genetic findings of MAS on a tissue-by-tissue basis in classically and nonclassically affected tissues.

DESIGN

This was a comprehensive autopsy and genetic analysis.

SETTING

The study was conducted at a tertiary referral university hospital.

PATIENTS: An adult male patient with MAS and severe disease burden including gigantism was the subject of the study.

INTERVENTION(S): Interventions included clinical, hormonal, and radiographic studies and gross and microscopic pathology analyses, conventional PCR, and droplet digital PCR analyses of affected and nonaffected tissues.

MAIN OUTCOME MEASURE: Pathological findings and the presence of GNAS1 mutations were measured.

RESULTS

The patient was diagnosed with MAS syndrome at 6 years of age based on the association of café-au-lait spots and radiological signs of polyostotic fibrous dysplasia. Gigantism developed and hyperprolactinemia, hypogonadotropic hypogonadism, and hyperparathyroidism were diagnosed throughout the adult period. The patient died at the age of 39 years from a pulmonary embolism. A detailed study revealed mosaiscism for the p.R201C GNAS1 mutation distributed across many endocrine and nonendocrine tissues. These genetically implicated tissues included rare or previously undescribed disease associations including primary hyperparathyroidism and hyperplasia of the thymus and endocrine pancreas.

CONCLUSIONS

This comprehensive pathological study of a single patient highlights the complex clinical profile of MAS and illustrates important advances in understanding the characteristics of somatic GNAS1-related pathology across a wide range of affected organs.