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Apetrei A, Molin A, Gruchy N, Godin M, Bracquemart C, Resbeut A, Rey G, Nadeau G, Richard N. A novel synonymous variant in exon 1 of GNAS gene results in a cryptic splice site and causes pseudohypoparathyroidism type 1A and pseudo-pseudohypoparathyroidism in a French family. Bone Rep 2021; 14:101073. [PMID: 33997150 PMCID: PMC8100090 DOI: 10.1016/j.bonr.2021.101073] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 04/17/2021] [Accepted: 04/20/2021] [Indexed: 12/31/2022] Open
Abstract
INTRODUCTION Pseudohypoparathyroidism type 1A (PHP1A) and pseudopseudohypoparathyroidism (PPHP) (Inactivating PTH/PTHrP Signaling Disorders type 2, IPPSD2) are two rare autosomal disorders caused by loss-of-function mutations on either maternal or paternal allele, respectively, in the imprinted GNAS gene, which encodes the α subunit of the ubiquitously-expressed stimulatory G protein (Gαs). CASE PRESENTATION We investigated a synonymous GNAS variant NM_001077488.2: c.108C>A / p.(Val36=) identified in a family presenting with IPPSD2 phenotype. In silico splicing prediction algorithms were in favor of a deleterious effect of this variant, by creating a new donor splicing site. The GNAS expression studies in blood suggested haploinsufficiency and showed an alternate splice product demonstrating the unmasking of a cryptic site, leading to a 34 base pairs deletion and the creation of a probable unstable RNA.We present the first familial case of IPPSD2 caused by a pathogenic synonymous variant in GNAS gene.
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Affiliation(s)
- Andreea Apetrei
- Normandy University, UNICAEN, Caen University Hospital, Department of Genetics, Reference Center of Rare Diseases of Calcium and Phosphorus Metabolism, EA 7450 BioTARGen, Caen, France
| | - Arnaud Molin
- Normandy University, UNICAEN, Caen University Hospital, Department of Genetics, Reference Center of Rare Diseases of Calcium and Phosphorus Metabolism, EA 7450 BioTARGen, Caen, France
| | - Nicolas Gruchy
- Normandy University, UNICAEN, Caen University Hospital, Department of Genetics, Reference Center of Rare Diseases of Calcium and Phosphorus Metabolism, EA 7450 BioTARGen, Caen, France
| | - Manon Godin
- Normandy University, UNICAEN, Caen University Hospital, Department of Genetics, Reference Center of Rare Diseases of Calcium and Phosphorus Metabolism, EA 7450 BioTARGen, Caen, France
| | - Claire Bracquemart
- Normandy University, UNICAEN, Caen University Hospital, Department of Genetics, Reference Center of Rare Diseases of Calcium and Phosphorus Metabolism, EA 7450 BioTARGen, Caen, France
| | - Antoine Resbeut
- Normandy University, UNICAEN, Caen University Hospital, Department of Genetics, Reference Center of Rare Diseases of Calcium and Phosphorus Metabolism, EA 7450 BioTARGen, Caen, France
| | - Gaëlle Rey
- Metropole Savoie Hospital Center, Genetics Department, Chambéry, France
| | - Gwenaël Nadeau
- Metropole Savoie Hospital Center, Genetics Department, Chambéry, France
| | - Nicolas Richard
- Normandy University, UNICAEN, Caen University Hospital, Department of Genetics, Reference Center of Rare Diseases of Calcium and Phosphorus Metabolism, EA 7450 BioTARGen, Caen, France
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