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Zhang X, Bi X, Wu Y, Xu P. Interpreting epigenetic causes of recurrent hypokalemia and seizures: Gitelman syndrome co-exist with pseudohypoparathyroidism type 1B. Nephrology (Carlton) 2024; 29:300-304. [PMID: 38233937 DOI: 10.1111/nep.14270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 12/04/2023] [Accepted: 12/28/2023] [Indexed: 01/19/2024]
Abstract
We describe a unique case of 27-year-old male with Gitelman syndrome (GS) co-exist with pseudohypoparathyroidism type 1B (PHP1B). The patient presented with a 5-year history of seizures, tetany, and numbness of the extremities. Further examinations showed recurrent hypokalemia, inappropriate kaliuresis, hypocalcemia, hyperphosphatemia, and elevated PTH levels. A novel variant of autosomal recessive GS (p.Val287Met SLC12A3) and a novel 492.3Kb deletion containing the whole of STX16, were discovered by a whole-exome sequencing. Following the diagnosis, calcitriol, calcium, and potassium supplements were started. Hematuria calcium and phosphorus levels, as well as blood potassium levels, have recovered and remained within normal ranges after 3 years of follow-up. Our findings have important consequences for supporting the idea that heterozygosity for variants have effects on the patients' clinical performance with autosomal recessive inheritance disorders. Further study is need for the putative effects of the variant. Likewise, further investigation with regards to the gene-gene interaction relations between GS and other electrolyte imbalance disorders is warranted.
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Affiliation(s)
- Xiuzhen Zhang
- Department of Endocrinology and Metabolism, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, Guangdong, China
| | - Xin Bi
- Guangzhou KingMed Center for Clinical Laboratory Co, Ltd., Guangzhou, Guangdong, China
| | - Yan Wu
- Department of Endocrinology and Metabolism, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, Guangdong, China
| | - Ping Xu
- Department of Endocrinology and Metabolism, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, Guangdong, China
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2
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Jüppner H. Pseudohypoparathyroidism: complex disease variants with unfortunate names. J Mol Endocrinol 2024; 72:e230104. [PMID: 37965945 PMCID: PMC10843601 DOI: 10.1530/jme-23-0104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 11/14/2023] [Indexed: 11/16/2023]
Abstract
Several human disorders are caused by genetic or epigenetic changes involving the GNAS locus on chromosome 20q13.3 that encodes the alpha-subunit of the stimulatory G protein (Gsα) and several splice variants thereof. Thus, pseudohypoparathyroidism type Ia (PHP1A) is caused by heterozygous inactivating mutations involving the maternal GNAS exons 1-13 resulting in characteristic abnormalities referred to as Albright's hereditary osteodystrophy (AHO) that are associated with resistance to several agonist ligands, particularly to parathyroid hormone (PTH), thereby leading to hypocalcemia and hyperphosphatemia. GNAS mutations involving the paternal Gsα exons also cause most of these AHO features, but without evidence for hormonal resistance, hence the term pseudopseudohypoparathyroidism (PPHP). Autosomal dominant pseudohypoparathyroidism type Ib (PHP1B) due to maternal GNAS or STX16 mutations (deletions, duplications, insertions, and inversions) is associated with epigenetic changes at one or several differentially methylated regions (DMRs) within GNAS. Unlike the inactivating Gsα mutations that cause PHP1A and PPHP, hormonal resistance is caused in all PHP1B variants by impaired Gsα expression due to loss of methylation at GNAS exon A/B, which can be associated in some familial cases with epigenetic changes at the other maternal GNAS DMRs. The genetic defect(s) responsible for sporadic PHP1B, the most frequent variant of this disorder, remain(s) unknown for the majority of patients. However, characteristic epigenetic GNAS changes can be readily detected that include a gain of methylation at the neuroendocrine secretory protein (NESP) DMR. Multiple genetic or epigenetic GNAS abnormalities can thus impair Gsα function or expression, consequently leading to inadequate cAMP-dependent signaling events downstream of various Gsα-coupled receptors.
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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, Massachusetts, USA
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3
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Urakawa T, Sano S, Kawashima S, Nakamura A, Shima H, Ohta M, Yamada Y, Nishida A, Narusawa H, Ohtsu Y, Matsubara K, Dateki S, Maruo Y, Fukami M, Ogata T, Kagami M. (Epi)genetic and clinical characteristics in 84 patients with pseudohypoparathyroidism type 1B. Eur J Endocrinol 2023; 189:590-600. [PMID: 38039118 DOI: 10.1093/ejendo/lvad163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 10/20/2023] [Accepted: 10/23/2023] [Indexed: 12/03/2023]
Abstract
OBJECTIVE Pseudohypoparathyroidism type 1B (PHP1B) caused by methylation defects of differentially methylated regions (DMRs) on the GNAS locus can be categorized into groups according to etiologies and methylation defect patterns of the DMRs. The aim of this study was to clarify the clinical characteristics of each group. DESIGN Comprehensive molecular analyses consisting of methylation, copy number, and microsatellite analyses. METHODS Eighty-four patients with PHP1B were included in this study. We classified them into 5 groups, namely, autosomal dominant inheritance-PHP1B (Group 1, G1), sporadic-PHP1B (G2), and atypical-PHP1B (G3-G5), based on the methylation defect patterns in 4 DMRs on the GNAS locus and etiologies and evaluated the clinical findings in each group and compared them among the groups. RESULTS G2 had the youngest age and the highest serum intact parathyroid hormone levels among the 5 groups at the time of diagnosis. The most common symptoms at the time of diagnosis were tetany in G1, and seizures or loss of consciousness in G2. Albright's hereditary osteodystrophy and PHP-suggestive features were most frequently observed in the G2 proband. Nine patients had neurodevelopmental disorders (NDs) consisting of mild to borderline intellectual disability and/or developmental delay. There were no significant correlations between the average methylation ratios of 7 CpG sites in the GNAS-A/B:TSS-DMR and hormonal and biochemical findings. CONCLUSION This study revealed the differences in some clinical characteristics, particularly clinical features, and ages at the time of diagnosis between G2 and other groups and detailed NDs observed in some patients with PHP1B.
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Affiliation(s)
- Tatsuki Urakawa
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
- Department of Pediatrics, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8102, Japan
| | - Shinichiro Sano
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
- Department of Endocrinology and Metabolism, Shizuoka Children's Hospital, Shizuoka 420-8660, Japan
| | - Sayaka Kawashima
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
- Department of Pediatrics, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan
| | - Akie Nakamura
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo 060-8648, Japan
| | - Hirohito Shima
- Department of Pediatrics, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan
| | - Motoki Ohta
- Department of Pediatrics, Saiseikai Shigaken Hospital, Ritto 520-3046, Japan
| | - Yuki Yamada
- Division of Pediatric Endocrinology and Metabolism, Children's Medical Center, Osaka City General Hospital, Osaka 534-0021, Japan
| | - Ai Nishida
- Diabetes and Endocrinology, Kameda Medical Center, Kamogawa 296-0041, Japan
| | - Hiromune Narusawa
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
| | - Yoshiaki Ohtsu
- Department of Pediatrics, Gunma University Graduate School of Medicine, Maebashi 371-0034, Japan
| | - Keiko Matsubara
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
| | - Sumito Dateki
- Department of Pediatrics, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8102, Japan
| | - Yoshihiro Maruo
- Department of Pediatrics, Shiga University of Medical Sciences, Otsu 520-2192, Japan
| | - Maki Fukami
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
| | - Tsutomu Ogata
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
- Department of Pediatrics, Hamamatsu Medical Center, Hamamatsu 432-8580, Japan
| | - Masayo Kagami
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
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Yang W, Zuo Y, Zhang N, Wang K, Zhang R, Chen Z, He Q. GNAS locus: bone related diseases and mouse models. Front Endocrinol (Lausanne) 2023; 14:1255864. [PMID: 37920253 PMCID: PMC10619756 DOI: 10.3389/fendo.2023.1255864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 09/29/2023] [Indexed: 11/04/2023] Open
Abstract
GNASis a complex locus characterized by multiple transcripts and an imprinting effect. It orchestrates a variety of physiological processes via numerous signaling pathways. Human diseases associated with the GNAS gene encompass fibrous dysplasia (FD), Albright's Hereditary Osteodystrophy (AHO), parathyroid hormone(PTH) resistance, and Progressive Osseous Heteroplasia (POH), among others. To facilitate the study of the GNAS locus and its associated diseases, researchers have developed a range of mouse models. In this review, we will systematically explore the GNAS locus, its related signaling pathways, the bone diseases associated with it, and the mouse models pertinent to these bone diseases.
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Affiliation(s)
- Wan Yang
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Yiyi Zuo
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Nuo Zhang
- School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Kangning Wang
- School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Runze Zhang
- School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Ziyi Chen
- School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Qing He
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
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5
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Iwasaki Y, Aksu C, Reyes M, Ay B, He Q, Bastepe M. The long-range interaction between two GNAS imprinting control regions delineates pseudohypoparathyroidism type 1B pathogenesis. J Clin Invest 2023; 133:e167953. [PMID: 36853809 PMCID: PMC10104902 DOI: 10.1172/jci167953] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 02/21/2023] [Indexed: 03/01/2023] Open
Abstract
Genetic defects of GNAS, the imprinted gene encoding the stimulatory G protein α-subunit, are responsible for multiple diseases. Abnormal GNAS imprinting causes pseudohypoparathyroidism type 1B (PHP1B), a prototype of mammalian end-organ hormone resistance. Hypomethylation at the maternally methylated GNAS A/B region is the only shared defect in patients with PHP1B. In autosomal dominant (AD) PHP1B kindreds, A/B hypomethylation is associated with maternal microdeletions at either the GNAS NESP55 differentially methylated region or the STX16 gene located approximately 170 kb upstream. Functional evidence is meager regarding the causality of these microdeletions. Moreover, the mechanisms linking A/B methylation and the putative imprinting control regions (ICRs) NESP-ICR and STX16-ICR remain unknown. Here, we generated a human embryonic stem cell model of AD-PHP1B by introducing ICR deletions using CRISPR/Cas9. With this model, we showed that the NESP-ICR is required for methylation and transcriptional silencing of A/B on the maternal allele. We also found that the SXT16-ICR is a long-range enhancer of NESP55 transcription, which originates from the maternal NESP-ICR. Furthermore, we demonstrated that the STX16-ICR is an embryonic stage-specific enhancer enabled by the direct binding of pluripotency factors. Our findings uncover an essential GNAS imprinting control mechanism and advance the molecular understanding of PHP1B pathogenesis.
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Affiliation(s)
- Yorihiro Iwasaki
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
- Tazuke Kofukai Medical Research Institute, Kitano Hospital, Osaka, Japan
| | - Cagri Aksu
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Monica Reyes
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Birol Ay
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Qing He
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
- The State Key Laboratory Breeding Base of Basic Science of Stomatology and Key Laboratory for Oral Biomedicine of the Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Murat Bastepe
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
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6
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Kawashima S, Yuno A, Sano S, Nakamura A, Ishiwata K, Kawasaki T, Hosomichi K, Nakabayashi K, Akutsu H, Saitsu H, Fukami M, Usui T, Ogata T, Kagami M. Familial Pseudohypoparathyroidism Type IB Associated with an SVA Retrotransposon Insertion in the GNAS Locus. J Bone Miner Res 2022; 37:1850-1859. [PMID: 35859320 DOI: 10.1002/jbmr.4652] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 07/12/2022] [Accepted: 07/16/2022] [Indexed: 11/09/2022]
Abstract
Loss of methylation (LOM) at GNAS-A/B:TSS-differentially methylated regions (DMRs) in the GNAS locus is observed in pseudohypoparathyroidism type 1B (PHP1B). Many PHP1B cases are sporadic, but autosomal dominant-PHP1B has a deletion involving NESP55 expressed from the maternal allele or STX16 located upstream of the GNAS locus on the maternal allele. We report the possible first familial PHP1B cases with retrotransposon insertion in the GNAS locus on the maternal allele. To our knowledge, they are the possible first cases with imprinting disorders caused by retrotransposon insertion. The two sibling cases experienced tetany and/or cramps from school age and had hypocalcemia and an increased serum intact parathyroid hormone (PTH) level together with overweight, round face, and normal intellectual levels. Methylation analysis for DMRs in the GNAS locus showed only LOM of the GNAS-A/B:TSS-DMR. Copy number abnormalities at STX16 and the GNAS locus were not detected by array comparative genomic hybridization. Whole-genome sequencing and Sanger sequencing revealed an approximately 1000-bp SVA retrotransposon insertion upstream of the first exon of A/B on the GNAS locus in these siblings. Whole-genome methylome analysis by Enzymatic Methyl-Seq in the siblings showed normal methylation status in the region surrounding the insertion site and mild LOM of the GNAS-A/B:TSS-DMR. We conducted transcriptome analysis using mRNA from skin fibroblasts and induced pluripotent stem cells (iPSCs) derived from the siblings and detected no aberrant NESP55 transcripts. Quantitative reverse-transcriptase PCR (qRT-PCR) analysis in skin fibroblasts showed increased A/B expression in the patients and no NESP55 expression, even in a control. qRT-PCR analysis in iPSCs showed decreased NESP55 expression with normal methylation status of the GNAS-NESP:TSS-DMR in the patients. The retrotransposon insertion in the siblings likely caused decreased NESP55 expression that could lead to increased A/B expression via LOM of the GNAS-A/B:TSS-DMR, subsequent reduced Gsα expression, and finally, PHP1B development. © 2022 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Sayaka Kawashima
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan.,Department of Pediatrics, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Akiko Yuno
- Department of Endocrinology and Metabolism, Kin-ikyo Chuo Hospital, Sapporo, Japan
| | - Shinichiro Sano
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan.,Department of Endocrinology and Metabolism, Shizuoka Children's Hospital, Shizuoka, Japan
| | - Akie Nakamura
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan.,Department of Pediatrics, Hokkaido University School of Medicine, Sapporo, Japan
| | - Keisuke Ishiwata
- Department of Maternal Fetal Biology, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Tomoyuki Kawasaki
- Department of Reproductive Medicine, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Kazuyoshi Hosomichi
- Department of Bioinformatics and Genomics, Graduate School of Advanced Preventive Medical Sciences, Kanazawa University, Kanazawa, Japan
| | - Kazuhiko Nakabayashi
- Department of Maternal Fetal Biology, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Hidenori Akutsu
- Department of Reproductive Medicine, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Hirotomo Saitsu
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Maki Fukami
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Takeshi Usui
- Research Support Center, Shizuoka General Hospital, Shizuoka, Japan.,Shizuoka Graduate University of Public Health, Shizuoka, Japan
| | - Tsutomu Ogata
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan.,Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan.,Department of Pediatrics, Hamamatsu Medical Center, Hamamatsu, Japan
| | - Masayo Kagami
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan
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7
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Miller DE, Hanna P, Galey M, Reyes M, Linglart A, Eichler EE, Jüppner H. Targeted Long-Read Sequencing Identifies a Retrotransposon Insertion as a Cause of Altered GNAS Exon A/B Methylation in a Family With Autosomal Dominant Pseudohypoparathyroidism Type 1b (PHP1B). J Bone Miner Res 2022; 37:1711-1719. [PMID: 35811283 PMCID: PMC9474630 DOI: 10.1002/jbmr.4647] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 06/14/2022] [Accepted: 07/01/2022] [Indexed: 11/09/2022]
Abstract
Pseudohypoparathyroidism type Ib (PHP1B) is characterized predominantly by resistance to parathyroid hormone (PTH) leading to hypocalcemia and hyperphosphatemia. These laboratory abnormalities are caused by maternal loss-of-methylation (LOM) at GNAS exon A/B, which reduces in cis expression of the stimulatory G protein α-subunit (Gsα). Paternal Gsα expression in proximal renal tubules is silenced through unknown mechanisms, hence LOM at exon A/B reduces further Gsα protein in this kidney portion, leading to PTH resistance. In a previously reported PHP1B family, affected members showed variable LOM at exon A/B, yet no genetic defect was found by whole-genome sequencing despite linkage to GNAS. Using targeted long-read sequencing (T-LRS), we discovered an approximately 2800-bp maternally inherited retrotransposon insertion nearly 1200 bp downstream of exon XL not found in public databases or in 13,675 DNA samples analyzed by short-read whole-genome sequencing. T-LRS data furthermore confirmed normal methylation at exons XL, AS, and NESP and showed that LOM comprising exon A/B is broader than previously thought. The retrotransposon most likely causes the observed epigenetic defect by impairing function of a maternally derived NESP transcript, consistent with findings in mice lacking full-length NESP mRNA and in PHP1B patients with deletion of exon NESP and adjacent intronic sequences. In addition to demonstrating that T-LRS is an effective strategy for identifying a small disease-causing variant that abolishes or severely reduces exon A/B methylation, our data demonstrate that this sequencing technology has major advantages for simultaneously identifying structural defects and altered methylation. © 2022 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Danny E. Miller
- Division of Genetic Medicine, Department of Pediatrics, University of Washington and Seattle Children’s Hospital, Seattle, WA
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA
| | - Patrick Hanna
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Miranda Galey
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA
| | - Monica Reyes
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Agnès Linglart
- Université Paris-Saclay, Inserm, Physiologie et physiopathologie endocrinienne; AP-HP, Department of molecular genetics, Bicêtre Paris-Saclay hospital, Le Kremlin Bicêtre, France
| | - Evan E. Eichler
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA
- Howard Hughes Medical Institute, University of Washington, Seattle, WA
- Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA
| | - Harald Jüppner
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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Hawkes CP, Al Jubeh JM, Li D, Tucker SE, Rajiyah T, Levine MA. Novel PTH Gene Mutations Causing Isolated Hypoparathyroidism. J Clin Endocrinol Metab 2022; 107:e2449-e2458. [PMID: 35165722 PMCID: PMC9113798 DOI: 10.1210/clinem/dgac086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Indexed: 11/19/2022]
Abstract
CONTEXT Parathyroid hormone (PTH) gene mutations represent a rare cause of familial isolated hypoparathyroidism (FIH). These defects can cause hypoparathyroidism with increased or decreased serum levels of PTH through 1) impaired PTH synthesis; 2) induction of parathyroid cell apoptosis; or 3) secretion of bioinactive PTH molecules. Eight pathogenic mutations of this gene have been described previously. OBJECTIVE Through describing 2 novel mutations of the PTH gene, we aim to extend the molecular basis for FIH and further refine the proposed mechanisms by which PTH mutations cause hypoparathyroidism. METHODS Proband case reports were compiled with extended family analysis. The probands in both kindreds presented before age 10 days with hypocalcemia and elevated phosphate levels. Proband A had low PTH levels, whereas these levels were elevated in Proband B. Proband B was initially diagnosed with pseudohypoparathyroidism. Methylation analysis was performed of CpG dinucleotides within 3 GNAS differentially methylated regions; whole-genome sequencing; and PTH infusion with analysis of nephrogenous 3',5'-cyclic adenosine 5'-monophosphate. RESULTS Proband A had a novel heterozygous sequence change in exon 2 of the PTH gene, c.46_47delinsAA (p.Ala16Lys), and proband B had a novel homozygous nucleotide transition in PTH exon 3 (c.128G > A; p.G43E) that led to replacement of glycine by glutamic acid at position 12 of PTH 1-84. PTH 1-34 infusion demonstrated that renal responsiveness to PTH was intact and not antagonized by circulating bioinactive PTH. CONCLUSION PTH gene mutations are uncommon causes of hypoparathyroidism, but can be misdiagnosed as disorders of gland development or receptor function if PTH levels are decreased or elevated, respectively. Genetic testing should be considered early in the diagnostic approach to these presentations.
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Affiliation(s)
- Colin P Hawkes
- Division of Endocrinology and Diabetes, The Children’s Hospital of Philadelphia (CHOP), Philadelphia, Pennsylvania, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Paediatrics and Child Health, University College Cork, Cork, Ireland
| | - Jamal M Al Jubeh
- Department of Pediatrics, Sheikh Khalifa Medical City, Abu Dhabi, United Arab Emirates
| | - Dong Li
- Center for Applied Genomics, CHOP, Philadelphia, Pennsylvania, USA
| | - Susan E Tucker
- Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, The University of Chicago, Chicago, Illinois, USA
| | - Tara Rajiyah
- Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, The University of Chicago, Chicago, Illinois, USA
| | - Michael A Levine
- Division of Endocrinology and Diabetes, The Children’s Hospital of Philadelphia (CHOP), Philadelphia, Pennsylvania, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Correspondence: Michael A. Levine, MD, Division of Pediatric Endocrinology and Diabetes, The Children’s Hospital of Philadelphia, ARC510A, 3615 Civic Center Blvd, Philadelphia, PA 19104, USA.
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9
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Campbell D, Reyes M, Kaygusuz SB, Abali S, Guran T, Bereket A, Kagami M, Turan S, Jüppner H. A novel deletion involving the first GNAS exon encoding Gsα causes PHP1A without methylation changes at exon A/B. Bone 2022; 157:116344. [PMID: 35104666 PMCID: PMC9301885 DOI: 10.1016/j.bone.2022.116344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 01/17/2022] [Accepted: 01/25/2022] [Indexed: 11/20/2022]
Abstract
Individuals affected by pseudohypoparathyroidism type 1A (PHP1A) display hyperphosphatemia and hypocalcemia despite elevated PTH levels, as well as features of Albright Hereditary Osteodystrophy (AHO). PHP1A is caused by variants involving the maternal GNAS exons 1-13 encoding the stimulatory G protein α-subunit (Gsα). MLPA and aCGH analysis led in a male PHP1A patient to identification of a de novo 1284-bp deletion involving GNAS exon 1. This novel variant overlaps with a previously identified 1438-bp deletion in another PHP1A patient (ref. Li et al. (2020) [13], patient 2) that extends from the exon 1 promoter into the up-stream intronic region. This latter deletion is associated with reduced methylation at GNAS exon A/B, i.e. the differentially methylated region (DMR) that is demethylated in most pseudohypoparathyroidism type 1B (PHP1B) patients. In contrast, genomic DNA from our patient revealed no evidence for an epigenetic GNAS defect as determined by MS-MLPA and pyrosequencing. These findings thus reduce the region, which, in addition to other nucleotide sequences telomeric of exon A/B, may undergo histone modifications or interacts with transcription factors and possibly as-yet unknown proteins that are required for establishing the maternal methylation imprints at this site. Taken together, nucleotide deletions or changes within an approximately 1300-bp region telomeric of exon A/B could be a cause of PHP1B variants with complete or incomplete loss-of-methylation at the exon A/B DMR. In addition, when investigating patients with suspected PHP1A, MLPA should be considered to search for structural abnormalities within this difficult to analyze genomic region comprising GNAS exon 1.
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Affiliation(s)
- Devon Campbell
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Monica Reyes
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Sare Betul Kaygusuz
- Department of Pediatric Endocrinology, Marmara University School of Medicine, Istanbul, Turkey
| | - Saygın Abali
- Department of Pediatric Endocrinology, Acibadem Mehmet Ali Aydinlar University School of Medicine, Istanbul, Turkey
| | - Tulay Guran
- Department of Pediatric Endocrinology, Marmara University School of Medicine, Istanbul, Turkey
| | - Abdullah Bereket
- Department of Pediatric Endocrinology, Marmara University School of Medicine, Istanbul, Turkey
| | - Masayo Kagami
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
| | - Serap Turan
- Department of Pediatric Endocrinology, Marmara University School of Medicine, Istanbul, Turkey
| | - Harald Jüppner
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA; Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
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10
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Milioto A, Reyes M, Hanna P, Kiuchi Z, Turan S, Zeve D, Agarwal C, Grigelioniene G, Chen A, Mericq V, Frangos M, Ten S, Mantovani G, Salusky IB, Tebben P, Jüppner H. Lack of GNAS Remethylation During Oogenesis May Be a Cause of Sporadic Pseudohypoparathyroidism Type Ib. J Clin Endocrinol Metab 2022; 107:e1610-e1619. [PMID: 34791361 PMCID: PMC8947795 DOI: 10.1210/clinem/dgab830] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Indexed: 12/11/2022]
Abstract
CONTEXT Pseudohypoparathyroidism type Ib (PHP1B) is characterized by hypocalcemia and hyperphosphatemia due to parathyroid hormone resistance in the proximal renal tubules. Maternal pathogenic STX16/GNAS variants leading to maternal epigenetic GNAS changes impair expression of the stimulatory G protein alpha-subunit (Gsα) thereby causing autosomal dominant PHP1B. In contrast, genetic defects responsible for sporadic PHP1B (sporPHP1B) remain mostly unknown. OBJECTIVE Determine whether PHP1B encountered after in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) causes GNAS remethylation defects similar to those in sporPHP1B. DESIGN Retrospective analysis. RESULTS Nine among 36 sporPHP1B patients investigated since 2000, all with loss of methylation (LOM) at the 3 maternal GNAS differentially methylated regions (DMRs) and gain of methylation at the paternal NESP DMR, had been conceived through IVF or ICSI. Besides abnormal GNAS methylation, IVF/ICSI PHP1B cases revealed no additional imprinting defects. Three of these PHP1B patients have dizygotic twins, and 4 have IVF/ICSI-conceived siblings, all with normal GNAS methylation; 2 unaffected younger siblings were conceived naturally. CONCLUSION Sporadic and IVF/ICSI-conceived PHP1B patients revealed indistinguishable epigenetic changes at all 4 GNAS DMRs, thus suggesting a similar underlying disease mechanism. Given that remethylation at the 3 maternal DMRs occurs during oogenesis, male factors are unlikely to cause LOM postfertilization. Instead, at least some of the sporPHP1B variants could be caused by a defect or defects in an oocyte-expressed gene that is required for fertility and for re-establishing maternal GNAS methylation imprints. It remains uncertain, however, whether the lack of GNAS remethylation alone and the resulting reduction in Gsα expression is sufficient to impair oocyte maturation.
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Affiliation(s)
- Angelo Milioto
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Monica Reyes
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Patrick Hanna
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Zentaro Kiuchi
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Serap Turan
- Department of Pediatric Endocrinology, Marmara University School of Medicine, Istanbul, Turkey
| | - Daniel Zeve
- Division of Endocrinology, Boston Children’s Hospital, Boston, MA, USA
| | | | - Giedre Grigelioniene
- Department of Molecular Medicine and Surgery, Karolinska Institutet, and Department of Clinical Genetics, Karolinska University Hospital Stockholm, Stockholm, Sweden
| | - Ang Chen
- Any Chen, Arizona Kidney Disease and Hypertension Center, Flagstaff, AZ, USA
| | - Veronica Mericq
- Institute of Maternal and Child Research (IDIMI), University of Chile, Santiago, Chile
| | | | - Svetlana Ten
- Consultant of Pediatric Endocrinology, Richmond University Medical Center, Staten Island, NY, USA
| | - Giovanna Mantovani
- Endocrinology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Isidro B Salusky
- Division of Nephrology, Department of Pediatrics, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Peter Tebben
- Department of Internal Medicine and Pediatrics, Division of Endocrinology and Metabolism, Mayo Clinic, Rochester, MN, USA
| | - Harald Jüppner
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Pediatric Nephrology Unit, Department of Pediatrics, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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11
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Kiuchi Z, Reyes M, Hanna P, Sharma A, DeClue T, Olney RC, Tebben P, Jüppner H. Progression of PTH Resistance in Autosomal Dominant Pseudohypoparathyroidism Type Ib Due to Maternal STX16 Deletions. J Clin Endocrinol Metab 2022; 107:e681-e687. [PMID: 34477200 PMCID: PMC8899049 DOI: 10.1210/clinem/dgab660] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 08/04/2021] [Indexed: 11/19/2022]
Abstract
CONTEXT Maternally inherited STX16 deletions that cause loss of methylation at GNAS exon A/B and thereby reduce Gsα expression are the most frequent cause of autosomal dominant pseudohypoparathyroidism type Ib (AD-PHP1B). Early identification of these disease-causing variants in the children of affected and unaffected female carriers would prompt treatment with calcium and calcitriol once parathyroid hormone (PTH) levels increase, thereby preventing hypocalcemia and associated complications. OBJECTIVE This study aimed to determine when PTH and calcium abnormalities develop after birth if a STX16 deletion is inherited maternally. METHODS Forty-four children of affected (n = 7) or unaffected (n = 7) females with a STX16 deletion were investigated for the presence of these variants. If a deletion was identified, measurement of PTH, calcium, phosphate, and thyrotropin (TSH) was advised. RESULTS The STX16 deletion that causes AD-PHP1B was identified in 25 children. Pretreatment laboratory results were available for 19 of those cases. Elevated PTH levels were detected by 2 years of age, and these were progressively higher if laboratory testing was first performed after establishing the genetic defect later in life. Total serum calcium levels remained within normal limits until about 5 years of age. TSH levels showed no consistent rise over time. CONCLUSION Establishing whether a STX16 deletion is inherited from a female carrier of a disease-causing variant rapidly establishes the diagnosis of AD-PHP1B. Several years before overt hypocalcemia developed, PTH levels increased, thereby establishing the onset of PTH resistance. Our findings provide diagnostic guidance and when treatment with calcium and calcitriol should be considered in order to prevent hypocalcemia and associated sequelae.
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Affiliation(s)
- Zentaro Kiuchi
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Monica Reyes
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Patrick Hanna
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Anu Sharma
- Division of Diabetes, Endocrinology and Metabolism, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Terry DeClue
- St Joseph’s Children’s Hospital, Tampa, FL 33607, USA
| | - Robert C Olney
- Nemours Children’s Specialty Care, Jacksonville, FL 32207, USA
| | - Peter Tebben
- Departments of Internal Medicine and Pediatrics, Divisions of Endocrinology and Metabolism, Mayo Clinic, Rochester, MN 55905, USA
| | - Harald Jüppner
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
- Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
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