Paternally inherited inactivating mutations of the GNAS1 gene in progressive osseous heteroplasia.
BACKGROUND
Progressive osseous heteroplasia (POH), an autosomal dominant disorder, is characterized by extensive dermal ossification during childhood, followed by disabling and widespread heterotopic ossification of skeletal muscle and deep connective tissue. Occasional reports of mild heterotopic ossification in Albright's hereditary osteodystrophy (AHO) and a recent report of two patients with AHO who had atypically extensive heterotopic ossification suggested a common genetic basis for the two disorders. AHO is caused by heterozygous inactivating mutations in the GNAS1 gene that result in decreased expression or function of the alpha subunit of the stimulatory G protein (Gsalpha) of adenylyl cyclase.


METHODS
We tested the hypothesis that GNAS1 mutations cause POH, using the polymerase chain reaction to amplify GNAS1 exons and exon-intron boundaries in 18 patients with sporadic or familial POH.


RESULTS
Heterozygous inactivating GNAS1 mutations were identified in 13 of the 18 probands with POH. The defective allele in POH is inherited exclusively from fathers, a result consistent with a model of imprinting for GNAS1. Direct evidence that the same mutation can cause either POH or AHO was observed within a single family, in which the phenotype correlated with the parental origin of the mutant allele.


CONCLUSIONS
Paternally inherited inactivating GNAS1 mutations cause POH. This finding extends the range of phenotypes derived from haplo insufficiency of GNAS1, provides evidence that imprinting is a regulatory mechanism for GNAS1 expression, and suggests that Gsalpha is a critical negative regulator of osteogenic commitment in nonosseous connective tissues.
Shore
Eileen M
EM
Department of Orthopaedic Surgery, University of Pennsylvania School of Medicine, Philadelphia 19104-6018, USA. shore@mail.med.upenn.edu
Ahn
Jaimo
J
Jan de Beur
Suzanne
S
Li
Ming
M
Xu
Meiqi
M
Gardner
R J McKinlay
RJ
Zasloff
Michael A
MA
Whyte
Michael P
MP
Levine
Michael A
MA
Kaplan
Frederick S
FS
D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D005220:Fathers; D005260:Female; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000235:genetics*; D015870:Gene Expression; D006579:Heterozygote; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D009999:Ossification, Heterotopic / Q000235:genetics*; D010375:Pedigree; D019683:Penetrance; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification
D012333:RNA, Messenger; D019205:GTP-Binding Protein alpha Subunits, Gs