Alternative titles and symbols : Ectopic ossification, familial; Osteoma cutis;
Description : Progressive osseous heteroplasia 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 (Kaplan et al., 1994). The molecular defect
causing POH is the same as that causing PPHP: an inactivating GNAS mutation caused
only by paternal inheritance of the mutant allele. However, patients with PPHP have
a constellation of physical findings referred to as Albright hereditary osteodystrophy
(AHO; see 103580) that is often not seen in patients with POH. Bastepe and Juppner
(2005) suggested that POH may be an extreme end of the spectrum of the AHO features
seen in PPHP.;
Inheritance : Autosomal dominant;
Molecular basis : Caused by mutation in the alpha-stimulatory subunit of the guanine nucleotide-binding
protein gene (GNAS1, 139320.0011);