Progressive osseous heteroplasia
Familial ectopic ossification
Type of disease: Rare conditions
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. People normally inherit one copy of each gene from their mother and one copy from their father. For most genes, both copies are active, or “turned on,” in all cells. For a small subset of genes, however, only one of the two copies is active. For some of these genes, only the copy inherited from a person’s father (the paternal copy) is active, while for other genes, only the copy inherited from a person’s mother (the maternal copy) is active. These differences in gene activation based on the gene’s parent of origin are caused by a phenomenon called genomic imprinting.
The GNAS gene has a complex genomic imprinting pattern. In some cells of the body the maternal copy of the gene is active, while in others the paternal copy is active. Progressive osseous heteroplasia occurs when mutations affect the paternal copy of the gene. Thus, progressive heteroplasia is usually inherited from the father. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.