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progressive osseous heteroplasia

Wednesday 18 June 2008

Definition: Progressive osseous heteroplasia (POH) is a rare autosomal dominant disorder characterized by dermal ossification beginning in infancy, followed by increasing and extensive bone formation in deep muscle and fascia.

Etiology

- The progressive osseous heteroplasia (POH) is caused by paternally inherited inactivating mutations of the GNAS1 gene (MIM.139320).

Albright hereditary osteodystrophy (AHO) (MIM.103580), fibrodysplasia ossificans progressive (FOP) (MIM.135100), and McCune-Albright syndrome (MAS) (MIM.174800) are allelic disorders, all of which are accompanied by ectopic ossification.

Differential diagnosis

Patients with POH do not have the characteristic malformation of the great toe seen in fibrodysplasia ossificans progressive (FOP) (MIM.135100). Patients with FOP do not have ossification of the skin in infancy. POH is also distinct from tumoral calcinosis (MIM.211900).

References

- Adegbite NS, Xu M, Kaplan FS, Shore EM, Pignolo RJ. Diagnostic and mutational spectrum of progressive osseous heteroplasia (POH) and other forms of GNAS-based heterotopic ossification. Am J Med Genet A. 2008 Jun 13. PMID: 18553568