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Abstract
Pseudohypoparathyroidism (PHP) and pseudopseudohypoparathyroidism (PPHP) are caused by mutations and/or epigenetic changes at the complex GNAS locus on chromosome 20q13.3 that undergoes parent-specific methylation changes at several differentially methylated regions (DMRs). GNAS encodes the alpha-subunit of the stimulatory G protein (Gsα) and several splice variants thereof. PHP type Ia (PHP1A) is caused by heterozygous inactivating mutations involving the maternal exons 1-13. Heterozygosity of these maternal GNAS mutations cause PTH-resistant hypocalcemia and hyperphosphatemia because paternal Gsα expression is suppressed in certain organs thus leading to little or no Gsα protein in the proximal renal tubules and other tissues. Besides biochemical abnormalities, PHP1A patients show developmental abnormalities, referred to as Albright's hereditary osteodystrophy (AHO). Some, but not all of these AHO features are encountered also in patients affected by PPHP, who carry paternal Gsα-specific mutations and typically show no laboratory abnormalities. Autosomal dominant PHP type Ib (AD-PHP1B) is caused by heterozygous maternal deletions within GNAS or STX16, which are associated with loss of methylation at the A/B DMR alone or at all maternally methylated GNAS exons. Loss of methylation of exon A/B and the resulting biallelic expression of A/B transcript reduces Gsα expression thus leading to hormonal resistance. Epigenetic changes at all differentially methylated GNAS regions are also observed in sporadic PHP1B, which is the most frequent PHP1B variant. However, this disease variant remains unresolved at the molecular level, except for rare cases with paternal uniparental isodisomy or heterodisomy of chromosome 20q (patUPD20q).
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Affiliation(s)
- Harald Jüppner
- Endocrine Unit, Department of Medicine and Pediatric Nephrology Unit, Department of Pediatrics, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Correspondence: Harald Jüppner, MD, Endocrine Unit, Thier 10, 50 Blossom Street, Massachusetts General Hospital, Boston, MA 02114, USA.
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Kotanidou EP, Tsinopoulou VR, Serbis A, Litou E, Galli-Tsinopoulou A. Pseudohypoparathyroidism Type 1A with Normocalcaemia, due to the Novel C.389A>G Variant of Exon 5 of the Guanine Nucleotide-Binding Protein, α-Stimulating Gene. J Bone Metab 2021; 28:85-89. [PMID: 33730787 PMCID: PMC7973403 DOI: 10.11005/jbm.2021.28.1.85] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 12/28/2020] [Indexed: 11/14/2022] Open
Abstract
Pseudohypoparathyroidism type 1A (PHP1A) is a rare disease caused by molecular defects in the maternally-inherited allele of the guanine nucleotide-binding protein, α-stimulating (GNAS) gene. The GNAS gene encodes the stimulatory G-protein α-subunit that regulates production of the second messenger cyclic adenosine monophosphate. Heterozygous inactivating mutations in these specific loci are responsible for a spectrum of phenotypic characteristics of the disease, including clinical features of the Albright’s hereditary osteodystrophy, due to resistance to parathyroid hormone (PTH). We report a case of PHP1A and explore the underlying novel point mutation of the GNAS gene that leads to an atypical PHP1A phenotype. A male patient with a round face, short stature, and brachydactyly accompanied by normocalcaemia and mild PTH resistance consulted at our center. The GNAS encoding region from the patient and both of his parents were amplified and sequenced directly in a sample of peripheral blood leukocytes. A novel c.389A>G point mutation in exon 5 of the GNAS gene, resulting in a p.Tyr130Cys peptidic chain change of the Gsα protein, detected in the proband, in heterozygous state. Sequencing of the GNAS gene from his parents did not reveal the c.389A>G mutation, confirming a de novo proband genotype. The maternal origin of the affected GNAS allele, along with mild PTH resistance, confirmed the PHP1A diagnosis. PHP1A, caused by inactivating GNAS mutations, presents a range of complex clinical phenotypes. The novel c.389A>G GNAS mutation presented in this case expands the spectrum of known PHP1A molecular defects and describes the associated phenotype.
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Affiliation(s)
- Eleni P Kotanidou
- Unit of Paediatric Endocrinology and Metabolism, Second Department of Paediatrics, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, AHEPA University General Hospital, Thessaloniki, Greece
| | - Vasiliki-Rengina Tsinopoulou
- Unit of Paediatric Endocrinology and Metabolism, Second Department of Paediatrics, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, AHEPA University General Hospital, Thessaloniki, Greece
| | - Anastasios Serbis
- Unit of Paediatric Endocrinology and Metabolism, Second Department of Paediatrics, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, AHEPA University General Hospital, Thessaloniki, Greece
| | - Eleni Litou
- Unit of Paediatric Endocrinology and Metabolism, Second Department of Paediatrics, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, AHEPA University General Hospital, Thessaloniki, Greece
| | - Assimina Galli-Tsinopoulou
- Unit of Paediatric Endocrinology and Metabolism, Second Department of Paediatrics, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, AHEPA University General Hospital, Thessaloniki, Greece
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Barik S, Farr S. Brachymetacarpia and brachymetatarsia: do we need to operate? EFORT Open Rev 2021; 6:15-23. [PMID: 33532083 PMCID: PMC7845563 DOI: 10.1302/2058-5241.6.200087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Brachymetacarpia and brachymetatarsia are rare congenital presentations denoted by shortening of metacarpals and metatarsals respectively, in which the deformity usually presents around childhood/early adolescence. The aetiology is usually congenital besides several other syndromic or endocrinologic associations. Cosmetic issues such as absence of a normal-looking knuckle while making a fist or disruption of finger-tip curvature besides functional issues are the main indications for surgical intervention in brachymetacarpia. In the foot, apart from cosmetic issues, pain due to transfer metatarsalgia as well as callosities along with toe deformities which lead to difficulty of using footwear are the main indications for intervention. Lengthening of the affected bone, either acute with grafting or gradual, is the mainstay of treatment. Gradual lengthening can be either single-stage as in callotasis, or two-stage where the primary procedure is followed by bone grafting after the length has been achieved. Adolescence, specifically between 12 and 15 years, is the preferred period for surgical intervention in these cases.
Cite this article: EFORT Open Rev 2021;6:15-23. DOI: 10.1302/2058-5241.6.200087
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Affiliation(s)
- Sitanshu Barik
- Pediatric Orthopedic Surgery, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
| | - Sebastian Farr
- Orthopedic Hospital Speising, Department of Pediatric Orthopaedics and Adult Foot and Ankle Surgery, Vienna, Austria
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Long XD, Xiong J, Mo ZH, Dong CS, Jin P. Identification of a novel GNAS mutation in a case of pseudohypoparathyroidism type 1A with normocalcemia. BMC MEDICAL GENETICS 2018; 19:132. [PMID: 30060753 PMCID: PMC6065144 DOI: 10.1186/s12881-018-0648-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 07/19/2018] [Indexed: 12/29/2022]
Abstract
BACKGROUND Pseudohypoparathyroidism type 1A (PHP1A) is a rare genetic disease primarily characterized by resistance to parathyroid hormone along with hormonal resistance and other features of Albright hereditary osteodystrophy (AHO). It is caused by heterozygous inactivating mutations in the maternal allele of the GNAS gene, which encodes the stimulatory G-protein alpha subunit (Gsα) and regulates production of the second messenger cyclic AMP (cAMP). Herein, we report a case of of PHP1A with atypical clinical manifestations (oligomenorrhea, subclinical hypothyroidism, and normocalcemia) and explore the underlying genetic cause in this patient. METHODS Blood samples were collected from the patient, her family members, and 100 healthy controls. The 13 exons and flanking splice sites of the GNAS gene were amplified by PCR and sequenced. To further assess whether the novel mutation resulted in gain or loss of function of Gsα, we examined the level of cAMP activity associated with this mutation through in vitro functional studies by introducing the target mutation into a human GNAS plasmid. RESULTS A novel heterozygous c.715A > G (p.N239D) mutation in exon 9 of the GNAS gene was identified in the patient. This mutation was also found in her mother, who was diagnosed with pseudopseudohypoparathyroidism. An in vitro cAMP assay showed a significant decrease in PTH-induced cAMP production in cells transfected with the mutant plasmid, compared to that in the wild-type control cells (P < 0.01), which was consistent with loss of Gsa activity. CONCLUSION We identified a novel GNAS mutation that altered Gsα function, which furthers our understanding of the pathogenesis of this disease. Screening for GNAS mutations should be considered in suspected cases of PHP1A even if the classical signs are not present.
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Affiliation(s)
- Xiao-dan Long
- Department of Endorcrinology, The third Xiangya Hospital Central South University, Tongzipo Road, 410007 Changsha, Hunan Province People’s Republic of China
| | - Jing Xiong
- Department of Endorcrinology, The third Xiangya Hospital Central South University, Tongzipo Road, 410007 Changsha, Hunan Province People’s Republic of China
| | - Zhao-hui Mo
- Department of Endorcrinology, The third Xiangya Hospital Central South University, Tongzipo Road, 410007 Changsha, Hunan Province People’s Republic of China
| | - Chang-sheng Dong
- Department of Anesthesia, The affiliated Tumor Hospital of Xiangya Medical School of Central South University, Changsha, 410007 Hunan China
| | - Ping Jin
- Department of Endorcrinology, The third Xiangya Hospital Central South University, Tongzipo Road, 410007 Changsha, Hunan Province People’s Republic of China
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Linglart A, Maupetit-Méhouas S, Silve C. GNAS -Related Loss-of-Function Disorders and the Role of Imprinting. Horm Res Paediatr 2016; 79:119-29. [PMID: 23548772 DOI: 10.1159/000348516] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 01/27/2013] [Indexed: 11/19/2022] Open
Abstract
GNAS (guanine nucleotide-binding protein, α stimulating) is a complex imprinted locus coding, besides the α-stimulatory subunit of the G protein, the paternally (extra-large, antisense and A/B) and maternally (neuroendocrine secretory protein) transcripts. Heterozygous mutations in the coding sequence of GNAS produce dominant phenotypes (combination of resistances to hormones signaling through G-protein-coupled receptors, osteodystrophy and obesity) that depend on the parental origin of the mutated allele. Likewise, alterations in the methylation at promoters of GNAS transcripts, associated or not with deletions of imprinting control regions in the nearby STX16 gene or within GNAS, prompt resistance to parathormone when affecting the maternal allele. Therefore, imprinting of GNAS is the determining factor for the variability of the phenotype. Knowledge of the various phenotypes is necessary for genetic counseling as well as an appropriate therapeutic balance between regular follow-up, prevention of disease complications and iatrogeny.
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Affiliation(s)
- Agnès Linglart
- Endocrinology and Diabetology for Children and French Center of Reference for Rare Disorders of Calcium and Phosphorus Metabolism, Bicêtre-Paris-Sud Hospital, Le Kremlin Bicêtre, France
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Thiele S, Werner R, Grötzinger J, Brix B, Staedt P, Struve D, Reiz B, Farida J, Hiort O. A positive genotype-phenotype correlation in a large cohort of patients with Pseudohypoparathyroidism Type Ia and Pseudo-pseudohypoparathyroidism and 33 newly identified mutations in the GNAS gene. Mol Genet Genomic Med 2014; 3:111-20. [PMID: 25802881 PMCID: PMC4367083 DOI: 10.1002/mgg3.117] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 09/21/2014] [Accepted: 09/23/2014] [Indexed: 12/17/2022] Open
Abstract
Maternally inherited inactivating GNAS mutations are the most common cause of parathyroid hormone (PTH) resistance and Albright hereditary osteodystrophy (AHO) leading to pseudohypoparathyroidism type Ia (PHPIa) due to Gsα deficiency. Paternally inherited inactivating mutations lead to isolated AHO signs characterizing pseudo-pseudohypoparathyroidism (PPHP). Mutations are distributed throughout the Gsα coding exons of GNAS and there is a lack of genotype–phenotype correlation. In this study, we sequenced exon 1–13 of GNAS in a large cohort of PHPIa- and PPHP patients and identified 58 different mutations in 88 patients and 27 relatives. Thirty-three mutations including 15 missense mutations were newly discovered. Furthermore, we found three hot spots: a known hotspot (p.D190MfsX14), a second at codon 166 (p.R166C), and a third at the exon 5 acceptor splice site (c.435 + 1G>A), found in 15, 5, and 4 unrelated patients, respectively. Comparing the clinical features to the molecular genetic data, a significantly higher occurrence of subcutaneous calcifications in patients harboring truncating versus missense mutations was demonstrated. Thus, in the largest cohort of PHPIa patients described to date, we extend the spectrum of known GNAS mutations and hot spots and demonstrate for the first time a correlation between the genetic defects and the expression of a clinical AHO-feature.
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Affiliation(s)
- Susanne Thiele
- Division of Experimental Paediatric Endocrinology and Diabetes, Department of Paediatrics, University of Lübeck Lübeck, Germany
| | - Ralf Werner
- Division of Experimental Paediatric Endocrinology and Diabetes, Department of Paediatrics, University of Lübeck Lübeck, Germany
| | - Joachim Grötzinger
- Institute of Biochemistry, Christian-Albrechts-University of Kiel Kiel, Germany
| | - Bettina Brix
- Division of Experimental Paediatric Endocrinology and Diabetes, Department of Paediatrics, University of Lübeck Lübeck, Germany
| | - Pia Staedt
- Division of Experimental Paediatric Endocrinology and Diabetes, Department of Paediatrics, University of Lübeck Lübeck, Germany
| | - Dagmar Struve
- Division of Experimental Paediatric Endocrinology and Diabetes, Department of Paediatrics, University of Lübeck Lübeck, Germany
| | - Benedikt Reiz
- Institute for Integrative and Experimental Genomics, University of Lübeck Lübeck, Germany
| | - Jennane Farida
- Service de Pédiatrie 2 unité, Hôpital universitaire Abderrahim Harouchi Chu ibn Rochd Casablanca, Morocco
| | - Olaf Hiort
- Division of Experimental Paediatric Endocrinology and Diabetes, Department of Paediatrics, University of Lübeck Lübeck, Germany
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Lemos MC, Thakker RV. GNAS mutations in Pseudohypoparathyroidism type 1a and related disorders. Hum Mutat 2014; 36:11-9. [PMID: 25219572 PMCID: PMC4309471 DOI: 10.1002/humu.22696] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Accepted: 09/02/2014] [Indexed: 12/13/2022]
Abstract
Pseudohypoparathyroidism type 1a (PHP1a) is characterized by hypocalcaemia and hyperphosphatemia due to parathyroid hormone resistance, in association with the features of Albright's hereditary osteodystrophy (AHO). PHP1a is caused by maternally inherited inactivating mutations of Gs-alpha, which is encoded by a complex imprinted locus termed GNAS. Paternally inherited mutations can lead either to pseudopseudohypoparathyroidism (PPHP) characterized by AHO alone, or to progressive osseous heteroplasia (POH), characterized by severe heterotopic ossification. The clinical aspects and molecular genetics of PHP1a and its related disorders are reviewed together with the 343 kindreds with Gs-alpha germline mutations reported so far in the literature. These 343 (176 different) mutations are scattered throughout the 13 exons that encode Gs-alpha and consist of 44.9% frameshift, 28.0% missense, 14.0% nonsense, and 9.0% splice-site mutations, 3.2% in-frame deletions or insertions, and 0.9% whole or partial gene deletions. Frameshift and other highly disruptive mutations were more frequent in the reported 37 POH kindreds than in PHP1a/PPHP kindreds (97.3% vs. 68.7%, P < 0.0001). This mutation update and respective genotype-phenotype data may be of use for diagnostic and research purposes and contribute to a better understanding of these complex disorders.
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Affiliation(s)
- Manuel C Lemos
- CICS-UBI, Health Sciences Research Centre, Faculty of Health Sciences, University of Beira Interior, Covilhã 6200-506, Portugal
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Elli FM, deSanctis L, Ceoloni B, Barbieri AM, Bordogna P, Beck-Peccoz P, Spada A, Mantovani G. Pseudohypoparathyroidism type Ia and pseudo-pseudohypoparathyroidism: the growing spectrum of GNAS inactivating mutations. Hum Mutat 2013; 34:411-6. [PMID: 23281139 DOI: 10.1002/humu.22265] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2012] [Accepted: 12/05/2012] [Indexed: 01/27/2023]
Abstract
Pseudohypoparathyroidism (PHP) is a rare heterogeneous genetic disorder characterized by end-organ resistance to parathyroid hormone due to partial deficiency of the α subunit of the stimulatory G protein (Gsα), encoded by the GNAS gene. Heterozygous inactivating GNAS mutations lead to either PHP type Ia (PHP-Ia), when maternally inherited, or pseudo-pseudohypoparathroidism (PPHP), if paternally derived. Both diseases feature typical physical traits identified as Albright's hereditary osteodystrophy in the presence or absence of multihormone resistance, respectively. GNAS mutations are detected in 60-70% of affected subjects, most patients/families harbor private mutations and no genotype-phenotype correlation has been found to date. We investigated Gsα-coding GNAS exons in a large panel of PHP-Ia-PPHP patients collected over the past decade in the two Italian referring centers for PHP. Of 49 patients carrying GNAS mutations, we identified 15 novel mutations in 19 patients. No apparent correlation was found between clinical/biochemical data and results of molecular analysis. Furthermore, we summarized the current knowledge of GNAS molecular pathology and updated the GNAS-locus-specific database. These results further expand the spectrum of GNAS mutations associated with PHP/PPHP and underline the importance of identifying such genetic alterations to supplement clinical evaluation and genetic counseling.
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Affiliation(s)
- Francesca Marta Elli
- Department of Clinical Sciences and Community Health, University of Milan, Endocrinology and Diabetology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
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Abstract
CONTEXT The term pseudohypoparathyroidism (PHP) indicates a group of heterogeneous disorders whose common feature is represented by impaired signaling of various hormones (primarily PTH) that activate cAMP-dependent pathways via Gsα protein. The two main subtypes of PHP, PHP type Ia, and Ib (PHP-Ia, PHP-Ib) are caused by molecular alterations within or upstream of the imprinted GNAS gene, which encodes Gsα and other translated and untranslated products. EVIDENCE ACQUISITION A PubMed search was used to identify the available studies (main query terms: pseudohypoparathyroidism; Albright hereditary osteodystrophy; GNAS; GNAS1; progressive osseous heteroplasia). The most relevant studies until February 2011 have been included in the review. EVIDENCE SYNTHESIS AND CONCLUSIONS Despite the first description of this disorder dates back to 1942, recent findings indicating complex epigenetic alterations beside classical mutations at the GNAS complex gene, pointed out the limitation of the actual classification of the disease, resulting in incorrect genetic counselling and diagnostic procedures, as well as the gap in our actual knowledge of the pathogenesis of these disorders. This review will focus on PHP type I, in particular its diagnosis, classification, treatment, and underlying molecular alterations.
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Affiliation(s)
- Giovanna Mantovani
- Endocrinology and Diabetology Unit, Department of Medical Sciences, Università degli Studi di Milano, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca' Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy.
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Bastepe M. The GNAS Locus: Quintessential Complex Gene Encoding Gsalpha, XLalphas, and other Imprinted Transcripts. Curr Genomics 2011; 8:398-414. [PMID: 19412439 PMCID: PMC2671723 DOI: 10.2174/138920207783406488] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2007] [Revised: 09/22/2007] [Accepted: 09/28/2007] [Indexed: 12/14/2022] Open
Abstract
The currently estimated number of genes in the human genome is much smaller than previously predicted. As an explanation for this disparity, most individual genes have multiple transcriptional units that represent a variety of biologically important gene products. GNAS exemplifies a gene of such complexity. One of its products is the alpha-subunit of the stimulatory heterotrimeric G protein (Gsalpha), a ubiquitous signaling protein essential for numerous different cellular responses. Loss-of-function and gain-of-function mutations within Gsalpha-coding GNAS exons are found in various human disorders, including Albright's hereditary osteodystrophy, pseudohypoparathyroidism, fibrous dysplasia of bone, and some tumors of different origin. While Gsalpha expression in most tissues is biallelic, paternal Gsalpha expression is silenced in a small number of tissues, playing an important role in the development of phenotypes associated with GNAS mutations. Additional products derived exclusively from the paternal GNAS allele include XLalphas, a protein partially identical to Gsalpha, and two non-coding RNA molecules, the A/B transcript and the antisense transcript. The maternal GNAS allele leads to NESP55, a chromogranin-like neuroendocrine secretory protein. In vivo animal models have demonstrated the importance of each of the exclusively imprinted GNAS products in normal mammalian physiology. However, although one or more of these products are also disrupted by most naturally occurring GNAS mutations, their roles in disease pathogenesis remain unknown. To further our understanding of the significance of this gene in physiology and pathophysiology, it will be important to elucidate the cellular roles and the mechanisms regulating the expression of each GNAS product.
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Affiliation(s)
- Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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Winter J, Hiort O, Hermanns P, Thiele S, Pohlenz J. A new heterozygous mutation (D196N) in the Gs alpha gene as a cause for pseudohypoparathyroidism type IA in a boy who had gallstones. J Pediatr Endocrinol Metab 2011; 24:297-301. [PMID: 21823526 DOI: 10.1515/jpem.2011.172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Pseudohypoparathyroidism (PHP) is characterized by hypocalcemia and hyperphosphatemia in association with an increased secretion of parathyroid hormone (PTH) due to decreased target tissue responsiveness to PTH. Patients with PHP type Ia are not only resistant to PTH, but also to other hormones that bind to receptors coupled to stimulatory G protein (Gsalpha). PHP Ia and Albright hereditary osteodystrophy (AHO) are caused by a reduced activity of the Gsalpha protein. Heterozygous inactivating Gs alpha (GNAS) gene mutations have been identified in these patients. METHODS We studied a boy with PHP Ia. During follow-up the patient developed elevated liver enzyme serum levels and abdominal discomfort. Gsalpha activity was measured in erythrocyte membranes from the patient and the GNAS coding region of Gsalpha sequenced. RESULTS Gsalpha activity was reduced (62%) and molecular analysis revealed a new heterozygous GNAS gene mutation (D196N). Gallstones were diagnosed and cholecystectomy was performed. Biochemical analysis revealed cholesterol stones, a condition that was not reported before in PHP Ia. CONCLUSIONS Cholesterol gallstones may rarely be associated with PHP Ia and should be taken into account.
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Affiliation(s)
- Julia Winter
- Children's Hospital of the Johannes Gutenberg-University, Mainz, Germany
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Wilkins JF, Úbeda F. Diseases associated with genomic imprinting. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2011; 101:401-45. [PMID: 21507360 DOI: 10.1016/b978-0-12-387685-0.00013-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Genomic imprinting is the phenomenon where the expression of a locus differs between the maternally and paternally inherited alleles. Typically, this manifests as transcriptional silencing of one of the alleles, although many genes are imprinted in a tissue- or isoform-specific manner. Diseases associated with imprinted genes include various cancers, disorders of growth and metabolism, and disorders in neurodevelopment, cognition, and behavior, including certain major psychiatric disorders. In many cases, the disease phenotypes associated with dysfunction at particular imprinted loci can be understood in terms of the evolutionary processes responsible for the origin of imprinting. Imprinted gene expression represents the outcome of an intragenomic evolutionary conflict, where natural selection favors different expression strategies for maternally and paternally inherited alleles. This conflict is reasonably well understood in the context of the early growth effects of imprinted genes, where paternally inherited alleles are selected to place a greater demand on maternal resources than are maternally inherited alleles. Less well understood are the origins of imprinted gene expression in the brain, and their effects on cognition and behavior. This chapter reviews the genetic diseases that are associated with imprinted genes, framed in terms of the evolutionary pressures acting on gene expression at those loci. We begin by reviewing the phenomenon and evolutionary origins of genomic imprinting. We then discuss diseases that are associated with genetic or epigenetic defects at particular imprinted loci, many of which are associated with abnormalities in growth and/or feeding behaviors that can be understood in terms of the asymmetric pressures of natural selection on maternally and paternally inherited alleles. We next described the evidence for imprinted gene effects on adult cognition and behavior, and the possible role of imprinted genes in the etiology of certain major psychiatric disorders. Finally, we conclude with a discussion of how imprinting, and the evolutionary-genetic conflicts that underlie it, may enhance both the frequency and morbidity of certain types of diseases.
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Miao ZM, Wang C, Wang BB, Meng DM, Su DM, Cheng Z, Wen QL, Han L, Yu Q, Ma X, Li CG. Identification of a novel mutation in a pseudohypoparathyroidism family. Int J Endocrinol 2011; 2011:509549. [PMID: 21822432 PMCID: PMC3142776 DOI: 10.1155/2011/509549] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 05/23/2011] [Indexed: 12/17/2022] Open
Abstract
Pseudohypoparathyroidism type Ia (PHP Ia) is defined as a series of disorders characterized by multihormone resistance in end-organs and Albright hereditary osteodystrophy (AHO) phenotype. PHP Ia is caused by heterozygous inactivating mutations in GNAS, which encodes the stimulatory G-protein alpha subunit (Gsa). A patient with typical clinical manifestations of pseudohypoparathyroidism (PHP) (round face, short stature, centripetal obesity, brachydactyly, and multi-hormone resistance: parathyroid hormone (PTH), thyroid-stimulating hormone (TSH), and gonadotropins) presented at our center. The sequence of the GNAS gene from the patient and her families revealed a novel missense mutation (Y318H) in the proband and her mother. An in vitro Gsa functional study showed that Gsa function was significantly impaired. These results stress the importance of GNAS gene investigation.
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Affiliation(s)
- Zhi-Min Miao
- Gout Laboratory, The Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, China
| | - Can Wang
- Gout Laboratory, The Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, China
| | - Bin-Bin Wang
- Graduate School, Peking Union Medical College, Beijing 100081, China
- Center of Genetics, National Research Institute for Family Planning, Beijing 100081, China
| | - Dong-Mei Meng
- Gout Laboratory, The Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, China
| | - Dong-Mei Su
- Graduate School, Peking Union Medical College, Beijing 100081, China
- Center of Genetics, National Research Institute for Family Planning, Beijing 100081, China
| | - Zhi Cheng
- Graduate School, Peking Union Medical College, Beijing 100081, China
- Center of Genetics, National Research Institute for Family Planning, Beijing 100081, China
| | - Qiao-Lian Wen
- Graduate School, Peking Union Medical College, Beijing 100081, China
- Center of Genetics, National Research Institute for Family Planning, Beijing 100081, China
| | - Lin Han
- Gout Laboratory, The Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, China
| | - Qing Yu
- Gout Laboratory, The Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, China
| | - Xu Ma
- Graduate School, Peking Union Medical College, Beijing 100081, China
- Center of Genetics, National Research Institute for Family Planning, Beijing 100081, China
- Center of Genetics, World Health Organization Collaborating Centre for Research in Human Reproduction, Beijing 100081, China
| | - Chang-Gui Li
- Gout Laboratory, The Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, China
- *Chang-Gui Li:
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Pseudohypoparathyreoidismus und epigenetische Veränderungen des GNAS-Genlocus. MED GENET-BERLIN 2010. [DOI: 10.1007/s11825-010-0249-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Zusammenfassung
Die Bezeichnung Pseudohypoparathyreoidismus (PHP) beschreibt eine heterogene Gruppe von Erkrankungen, die durch eine Endorganresistenz gegenüber Parathormon (PTH) gekennzeichnet sind. Sie werden durch eine Defizienz der α-Untereinheit stimulierender G-Proteine (Gsα) verursacht. Gsα ist essenziell für die Signalvermittlung durch extrazelluläre Liganden über mehr als 1000 verschiedene G-Protein-gekoppelte Rezeptoren in das Zellinnere. Durch eine gewebespezifische Prägung verursachen maternale, autosomal-dominant vererbte Mutationen in dem für Gsα kodierenden GNAS-Genlocus PTH-Resistenz und klinische Zeichen der hereditären Albright-Osteodystrophie (AHO), einschließlich Brachymetakarpie, Kleinwuchs, subkutaner Ossifikationen und mentaler Retardierung (PHP-Typ Ia). Paternal vererbte GNAS-Mutationen führen zu selektiven AHO-Zeichen ohne Parathormonresistenz (Pseudo-PHP). Der PHP-Typ Ib, bei dem eine isolierte PTH-Resistenz vorliegt, wird durch heterozygote, maternal vererbte Deletionen stromaufwärts vom oder innerhalb des GNAS-Locus hervorgerufen, die durch eine Störung des Imprintingmusters eine gewebespezifische Stilllegung der Gsα-Expression hervorrufen. Diese Patienten zeigen in der Regel keine Zeichen der AHO. In der vorliegenden Arbeit wird ein Überblick über die Rolle epigenetischer Faktoren bei der Ätiopathogenese verschiedener PHP-Formen gegeben.
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de Nanclares GP, Fernández-Rebollo E, Gaztambide S, Castaño L. Genetics of pseudohypoparathyroidism: bases for proper genetic counselling. ENDOCRINOLOGIA Y NUTRICION : ORGANO DE LA SOCIEDAD ESPANOLA DE ENDOCRINOLOGIA Y NUTRICION 2008; 55:476-483. [PMID: 22980463 DOI: 10.1016/s1575-0922(08)75844-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Accepted: 09/10/2008] [Indexed: 06/01/2023]
Abstract
Pseudohypoparathyroidism (PHP) is characterized by hypocalcemia and hyperphosphatemia due to resistance to parathyroid hormone (PTH). Patients with PHP-Ia often show additional hormone resistance and characteristic physical features that are collectively termed Albright's hereditary osteodystrophy (AHO). These features are also present in pseudopseudohypoparathyroidism (PPHP), but patients with this disorder do not show hormone resistance. PHP-Ib patients, on the other hand, predominantly show renal PTH resistance and lack features of AHO. From the genetic point of view, PHP-I is caused by defects in the GNAS gene or in the 5' region of this gene locus. PHP-Ia is caused by heterozygous inactivating mutations in any of the 13 exons codifying the alpha subunit of the stimulatory guanine nucleotide-binding protein (Gsα), while PHP-Ib is due to alterations in the methylation pattern of the 5' regions of the locus, usually associated with upstream microdeletions that are maternally transmitted. The imprinting pattern that affects the GNAS locus has important implications for the inheritance pattern and consequently for appropriate genetic counselling.
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Affiliation(s)
- Guiomar Pérez de Nanclares
- Grupo de Investigación en Endocrinología y Diabetes. Hospital de Cruces. Baracaldo. Vizcaya. España; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII. Baracaldo. Vizcaya. España
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Fernandez-Rebollo E, Barrio R, Pérez-Nanclares G, Carcavilla A, Garin I, Castaño L, de Nanclares GP. New mutation type in pseudohypoparathyroidism type Ia. Clin Endocrinol (Oxf) 2008; 69:705-12. [PMID: 18394017 DOI: 10.1111/j.1365-2265.2008.03255.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
CONTEXT The GNAS gene encodes the alpha-subunit of the stimulatory G proteins, which play a crucial role in intracellular signal transduction of peptide and neurotransmitter receptors. Heterozygous inactivating maternally inherited mutations of GNAS (including translation initiation mutations, amino acid substitutions, nonsense mutations, splice site mutations and small insertions or deletions) lead to a phenotype in which Albright hereditary osteodystrophy is associated with pseudohypoparathyroidism type Ia. OBJECTIVE We sought to identify the molecular defect in a patient who was thought to have PHP-Ia. METHODS AND RESULTS The GNAS gene of a 5-year-old boy with brachydactily, mental retardation, pseudohypoparathyroidism and congenital hypothyroidism was investigated. We found a heterozygous inversion of exon 2 and part of intron 1 of de novo origin. Molecular studies of cDNA from blood RNA demonstrated that both the normal and the mutant variants were stable and that new splice-sites were generated. CONCLUSION This report demonstrates the first evidence for an inversion at the GNAS gene responsible of pseudohypoparathyroidism type Ia.
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Tamada Y, Kanda S, Suzuki H, Tajima T, Nishiyama T. A pseudohypoparathyroidism type Ia patient with normocalcemia. Endocr J 2008; 55:169-73. [PMID: 18250541 DOI: 10.1507/endocrj.k07e-019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Pseudohypoparathyroidism type Ia (PHP-Ia), one of 4 types of PHP, is a genetic disease characterized by clinical hypoparathyroidism caused by parathyroid hormone (PTH) resistance. In addition, patients with PHP-Ia show resistance to other hormones as well as Albright's hereditary osteodystrophy (AHO), a constellation of features including short stature, obesity, brachydactyly, ectopic ossifications, and/or mental retardation. Hypocalcemia is one of the hallmarks of PHP-Ia, but several PHP-Ia patients have been described to have normocalcemia. We encountered a 10-year-old girl with typical Albright's hereditary osteodystrophy with round face, short stature, brachydactyly, and obesity. Biochemical examination showed normocalcemia and increased PTH levels. Ellsworth-Howard test did not show any responses of urinary cAMP and phosphate. Based on these findings, she was diagnosed as having PHP-Ia with normocalcemia. Sequencing analysis of the GNAS gene identified a heterozygous missense mutation in exon 13 (R385H), which was previously reported in a PHP-Ia patient. The exact reason for her normocalcemia is not determined, but we must recognize heterogeneous biochemical findings even in PHP-Ia.
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Affiliation(s)
- Yasuko Tamada
- Department of Public Health, Kansai Medical University, Moriguchi, Japan
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Mouallem M, Shaharabany M, Weintrob N, Shalitin S, Nagelberg N, Shapira H, Zadik Z, Farfel Z. Cognitive impairment is prevalent in pseudohypoparathyroidism type Ia, but not in pseudopseudohypoparathyroidism: possible cerebral imprinting of Gsalpha. Clin Endocrinol (Oxf) 2008; 68:233-9. [PMID: 17803690 DOI: 10.1111/j.1365-2265.2007.03025.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Pseudohypoparathyroidism type Ia (PHP-Ia) is a hereditary disorder characterized by resistance to multiple hormones that work via cAMP such as PTH and TSH, accompanied by typical skeletal features including short stature and brachydactyly, termed Albright hereditary osteodystrophy (AHO). In affected kindreds, some members may have AHO but not hormone resistance; they are termed as pseudopseudohypoparathyroidism (PPHP). The molecular basis for the disorder is heterozygous inactivating mutation of the Gsalpha gene. In affected families, subjects with both PHP-Ia and PPHP have the same Gsalpha mutations. The skeletal features common to PPHP and PHP-Ia are presumably caused by tissue-specific Gsalpha haploinsufficiency. Other features that distinguish between PPHP and PHP-Ia, such as the multihormone resistance, are presumably caused by tissue-specific paternal imprinting of Gsalpha. This suggests that major differences in phenotype between PHP-Ia and PPHP point to specific tissues with Gsalpha imprinting. One such major difference may be cognitive function in PHP-Ia and PPHP. DESIGN Description of a large family with PHP-Ia and PPHP. PATIENTS Eleven affected subjects with PHP-Ia or PPHP in one family. MEASUREMENTS Cognitive impairment (CI) was defined by a history of developmental delay, learning disability and the Wechsler intelligence scale. RESULTS CI occurred only in the five PHP-Ia but not in the six PPHP subjects. Hypothyroidism which occurred in all PHP-Ia subjects was apparently not the cause of CI as it was mild, and was treated promptly. Analysis of additional Israeli cases, and the published cases from the literature, all with documented Gsalpha mutations, revealed that CI is prevalent in PHP-Ia [60 of 77 subjects (79%)] but not in PPHP [3 of 30 subjects (10%)] (P < 1 x 10(-6)). CONCLUSION We suggest that Gsalpha is imprinted in the brain.
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Affiliation(s)
- M Mouallem
- Department of Medicine E, Sheba Medical Center, Tel Hashomer, and Tel Aviv University School of Medicine, Tel Aviv, Israel
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