GNAS

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GNAS

A locus on chromosome 20q13.3 that has a highly complex imprinted expression pattern, giving rise to maternally, paternally and biallelically expressed transcripts derived from four alternative promoters and 5' exons. Some transcripts have a differentially methylated region (DMR) at their 5' exons. This DMR is commonly found in imprinted genes and correlates with transcript expression; one transcript produced from this locus and the antisense transcript are paternally expressed, noncoding RNAs, which may regulate regional imprinting. Alternative splicing of downstream exons results in different forms of the stimulatory G-protein alpha subunit, a key component of the classical signal-transduction pathway linking receptor-ligand interactions to adenylyl cyclase activation and various cellular responses.

Molecular pathology
GNAS mutations have been linked to pseudohypoparathyroidism types 1a and 1b, Albright hereditary osteodystrophy, pseudopseudohypoparathyroidism, McCune-Albright syndrome, progressive osseus heteroplasia, polyostotic fibrous dysplasia of bone and pituitary tumours.
References in periodicals archive ?
The down regulation of the GNAS1 gene via siRNA leads to the increased expression of Cbfa1 that would stimulate the production of bone-differentiating proteins such as osteopontin, collagen I, and osteocalcin [3, 15].
We hypothesized blocking of the bone differentiation pathway via siRNA against GNAS1 (siGNAS1) and the hypoxia pathway via siRNA against PHD2 (siPHD2) would affect MSC proliferation and expression of collagen, osteopontin, and alkaline phosphatase (ALP).
McCune-Albright syndrome and disorders due to activating mutations of GNAS1.
GNAS1 mutations occur more commonly than previously thought in intramuscular myxoma.
Recently, it was recognized that both localized and diffuse FD are nonneoplastic processes associated with postzygotic-activating mutations of signal-transducing G proteins encoded by GNAS1 on chromosome 20.
The various conditions associated with hypophosphataemic rickets/osteomalacia and possible mechanisms for the hypophosphataemia Condition Abnormality FGF23 related: X-linked hypophosphataemic Inactivating mutation of PHEX rickets (XLH) Autosomal dominant hypophosphataemic Activating mutation of FGF-23 rickets (ADHR) Autosomal recessive Inactivating mutation of DMP1 hypophosphataemic rickets (ARHR) Polyostotic fibrous dysplasia Excessive production of FGF-23 with or without McCune Albright by the fibrous dysplasia syndrome (somatic activating mutation in GNAS1 gene) Tumour induced rickets/ Excessive production of osteomalacia (TIO) phosphatonin (e.