Progressive osseous heteroplasia is a disorder in which bone forms within skin and muscle tissue. Bone that forms outside the skeleton is called heterotopic or ectopic bone. In progressive osseous heteroplasia, ectopic bone formation begins in the deep layers of the skin (dermis and subcutaneous fat) and gradually moves into other tissues such as skeletal muscle and tendons. The bony lesions within the skin may be painful and may develop into open sores (ulcers). Over time, joints can become involved, resulting in impaired mobility.

Progressive osseous heteroplasia is caused by a mutation in the GNAS gene. The GNAS gene provides instructions for making one part of a protein complex called a guanine nucleotide-binding protein, or a G protein.

Progressive osseous heteroplasia is a rare condition. Its exact incidence is unknown.

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

Published Date: February 01, 2018
Published By: National Institutes of Health