McCune Albright syndrome is an unusual type of disease with varied symptoms. In this disease, a mutation occurs sometime after conception, affecting only some of the body's cells. The number and type of symptoms depend on which cells—and thus which organs—are affected.
Scientists have found that the mutation affects the gene that codes for he same G-protein involved in cholera. This G-protein gets stuck in the "on" position. In skin cells, this causes darker than normal pigment. If the mutation affects bone cells, it causes weakness and fractures. In hormone-producing cells, the mutation causes the release of excess hormones.
About the Photo:
Skin cells and bone cells are affected in this 4-year-old girl with McCune Albright syndrome. She wears a body cast because of bone fractures. The mosaic pattern of darkened skin is visible.
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Courtesy of the Developmental Endocrinology Branch, NICHD