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Tüysüz B, Usluer E, Uludağ Alkaya D, Ocak S, Saygılı S, Şeker A, Apak H. The molecular spectrum of Turkish osteopetrosis and related osteoclast disorders with natural history, including a candidate gene, CCDC120. Bone 2023; 177:116897. [PMID: 37704070 DOI: 10.1016/j.bone.2023.116897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 08/21/2023] [Accepted: 09/08/2023] [Indexed: 09/15/2023]
Abstract
BACKGROUND Osteopetrosis and related osteoclastic disorders are a heterogeneous group of inherited diseases characterized by increased bone density. The aim of this study is to investigate the molecular spectrum and natural history of the clinical and radiological features of these disorders. METHODS 28 patients from 20 families were enrolled in the study; 20 of them were followed for a period of 1-16 years. Targeted gene analysis and whole-exome sequencing (WES) were performed. RESULTS Biallelic mutations in CLCN7 and TCIRG1 were detected in three families each, in TNFRSF11A and CA2 in two families each, and in SNX10 in one family in the osteopetrosis group. A heterozygous variant in CLCN7 was also found in one family. In the osteopetrosis and related osteoclast disorders group, three different variants in CTSK were detected in five families with pycnodysostosis and a SLC29A3 variant causing dysosteosclerosis was detected in one family. In autosomal recessive osteopetrosis (ARO), a malignant infantile form, four patients died during follow-up, two of whom had undergone hematopoietic stem cell transplantation. Interestingly, all patients had osteopetrorickets of the long bone metaphyses in infancy, typical skeletal features such as Erlenmeyer flask deformity and bone-in-bone appearance that developed toward the end of early childhood. Two siblings with a biallelic missense mutation in CLCN7 and one patient with the compound heterozygous novel splicing variants in intron 15 and 17 in TCIRG1 corresponded to the intermediate form of ARO (IARO); there was intrafamilial clinical heterogeneity in the family with the CLCN7 variant. One of two patients with IARO and distal tubular acidosis was found to have a large deletion in CA2. In one family, two siblings with a heterozygous mutation in CLCN7 were affected, whereas the father with the same mutation was asymptomatic. In WES analysis of three brothers from a family without mutations in osteopetrosis genes, a hemizygous missense variant in CCDC120, a novel gene, was found to be associated with high bone mass. CONCLUSION This study extended the natural history of the different types of osteopetrosis and also introduced a candidate gene, CCDC120, potentially causing osteopetrosis.
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Affiliation(s)
- Beyhan Tüysüz
- Istanbul University-Cerrahpasa, Cerrahpasa Faculty of Medicine, Department of Pediatric Genetics, Istanbul, Turkey.
| | - Esra Usluer
- Istanbul University-Cerrahpasa, Cerrahpasa Faculty of Medicine, Department of Pediatric Genetics, Istanbul, Turkey
| | - Dilek Uludağ Alkaya
- Istanbul University-Cerrahpasa, Cerrahpasa Faculty of Medicine, Department of Pediatric Genetics, Istanbul, Turkey
| | - Süheyla Ocak
- Istanbul University-Cerrahpasa, Cerrahpasa Faculty of Medicine, Department of Pediatric Hematology, Istanbul, Turkey
| | - Seha Saygılı
- Istanbul University-Cerrahpasa, Cerrahpasa Faculty of Medicine, Department of Pediatric Nephrology, Istanbul, Turkey
| | - Ali Şeker
- Istanbul University-Cerrahpasa, Cerrahpasa Faculty of Medicine, Department of Orthopedics and Traumatology, Istanbul, Turkey
| | - Hilmi Apak
- Istanbul University-Cerrahpasa, Cerrahpasa Faculty of Medicine, Department of Pediatric Hematology, Istanbul, Turkey
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The Role of the Lysosomal Cl−/H+ Antiporter ClC-7 in Osteopetrosis and Neurodegeneration. Cells 2022; 11:cells11030366. [PMID: 35159175 PMCID: PMC8833911 DOI: 10.3390/cells11030366] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/16/2022] [Accepted: 01/19/2022] [Indexed: 12/04/2022] Open
Abstract
CLC proteins comprise Cl− channels and anion/H+ antiporters involved in several fundamental physiological processes. ClC-7 is a lysosomal Cl−/H+ antiporter that together with its beta subunit Ostm1 has a critical role in the ionic homeostasis of lysosomes and of the osteoclasts’ resorption lacuna, although the specific underlying mechanism has so far remained elusive. Mutations in ClC-7 cause osteopetrosis, but also a form of lysosomal storage disease and neurodegeneration. Interestingly, both loss-of- and gain-of-function mutations of ClC-7 can be pathogenic, but the mechanistic implications of this finding are still unclear. This review will focus on the recent advances in our understanding of the biophysical properties of ClC-7 and of its role in human diseases with a focus on osteopetrosis and neurodegeneration.
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Overlapping Phenotypes in Osteopetrosis and Pycnodysostosis in Asian-Indians. Case Rep Genet 2021; 2021:7133508. [PMID: 34777883 PMCID: PMC8580671 DOI: 10.1155/2021/7133508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 10/04/2021] [Indexed: 11/17/2022] Open
Abstract
Osteopetrosis is a disorder characterized by high bone density, hepatosplenomegaly, visual and hearing loss, and anemia. Pycnodysostosis presents with short stature, acroosteolysis, and dense bones. We, hereby, present here a family with autosomal dominant osteopetrosis and also children with recessive osteopetrosis and pycnodysostosis. The molecular confirmation was done in 3 cases. Genetic heterogeneity in clinical presentation is discussed here. Further studies will help in identifying epigenetic alterations and population-specific variants and also developing targeted therapies.
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Squires KE, Montañez-Miranda C, Pandya RR, Torres MP, Hepler JR. Genetic Analysis of Rare Human Variants of Regulators of G Protein Signaling Proteins and Their Role in Human Physiology and Disease. Pharmacol Rev 2018; 70:446-474. [PMID: 29871944 DOI: 10.1124/pr.117.015354] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Regulators of G protein signaling (RGS) proteins modulate the physiologic actions of many neurotransmitters, hormones, and other signaling molecules. Human RGS proteins comprise a family of 20 canonical proteins that bind directly to G protein-coupled receptors/G protein complexes to limit the lifetime of their signaling events, which regulate all aspects of cell and organ physiology. Genetic variations account for diverse human traits and individual predispositions to disease. RGS proteins contribute to many complex polygenic human traits and pathologies such as hypertension, atherosclerosis, schizophrenia, depression, addiction, cancers, and many others. Recent analysis indicates that most human diseases are due to extremely rare genetic variants. In this study, we summarize physiologic roles for RGS proteins and links to human diseases/traits and report rare variants found within each human RGS protein exome sequence derived from global population studies. Each RGS sequence is analyzed using recently described bioinformatics and proteomic tools for measures of missense tolerance ratio paired with combined annotation-dependent depletion scores, and protein post-translational modification (PTM) alignment cluster analysis. We highlight selected variants within the well-studied RGS domain that likely disrupt RGS protein functions and provide comprehensive variant and PTM data for each RGS protein for future study. We propose that rare variants in functionally sensitive regions of RGS proteins confer profound change-of-function phenotypes that may contribute, in newly appreciated ways, to complex human diseases and/or traits. This information provides investigators with a valuable database to explore variation in RGS protein function, and for targeting RGS proteins as future therapeutic targets.
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Affiliation(s)
- Katherine E Squires
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
| | - Carolina Montañez-Miranda
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
| | - Rushika R Pandya
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
| | - Matthew P Torres
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
| | - John R Hepler
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
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Khan MA, Ullah A, Naeem M. Whole exome sequencing identified two novel homozygous missense variants in the same codon of CLCN7 underlying autosomal recessive infantile malignant osteopetrosis in a Pakistani family. Mol Biol Rep 2018; 45:565-570. [PMID: 29926385 DOI: 10.1007/s11033-018-4194-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 05/16/2018] [Indexed: 01/05/2023]
Abstract
Autosomal recessive osteopetrosis is a severe fatal disorder with an average incidence of around 1:250,000. It is diagnosed soon after birth or within the 1st year of life with severe symptoms of abnormal bone remodelling. This study was aimed to identify the underlying genetic cause of the disease in a Pakistani family segregating infantile malignant osteopetrosis in autosomal recessive pattern. Whole exome sequencing of the proband was performed using the 51 Mb SureSelect V4 library kit and sequenced using the Illumina HiSeq2500 sequencing system. The reads were analysed using standard bioinformatic data analysis pipeline. The genotype of candidate variants was confirmed in the proband and his normal parents by Sanger sequencing. Two novel homozygous missense variants were found in the same codon 204 of CLCN7 NM_001287.5:c.[610A>T;612C>G] predicting p.(Ser204Trp) variant in the protein. Sanger sequencing and RFLP assay verified that both these variants were heterozygous in the unaffected parents. Moreover, these variants were not detected in the unrelated healthy Pakistani subjects (200 chromosomes), ExAC, dbSNP, or the 1000 Genomes Project data. Multiple bioinformatics tools unanimously predicted the p.(Ser204Trp) variant as deleterious. CLCN7 mutation p.(Ser204Trp) is the likely cause of the osteopetrosis disease in the Pakistani family. This study expands the restricted spectrum of CLCN7 mutations associated with infantile malignant osteopetrosis and indicates clinical significance of whole exome sequencing in the diagnosis of clinically and genetically heterogenous osteopetrosis phenotype. These data should be helpful in the improved genetic counselling, carrier identification and prenatal diagnosis of the affected family.
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Affiliation(s)
- Muhammad Aman Khan
- Medical Genetics Research Laboratory, Department of Biotechnology, Quaid-i-Azam University, Islamabad, 45320, Pakistan
- Department of Pathology and Laboratory Medicine, Lady Reading Hospital, Peshawar, Pakistan
| | - Aman Ullah
- Medical Genetics Research Laboratory, Department of Biotechnology, Quaid-i-Azam University, Islamabad, 45320, Pakistan
| | - Muhammad Naeem
- Medical Genetics Research Laboratory, Department of Biotechnology, Quaid-i-Azam University, Islamabad, 45320, Pakistan.
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Abstract
PURPOSE OF REVIEW The term osteopetrosis refers to a group of rare skeletal diseases sharing the hallmark of a generalized increase in bone density owing to a defect in bone resorption. Osteopetrosis is clinically and genetically heterogeneous, and a precise molecular classification is relevant for prognosis and treatment. Here, we review recent data on the pathogenesis of this disorder. RECENT FINDINGS Novel mutations in known genes as well as defects in new genes have been recently reported, further expanding the spectrum of molecular defects leading to osteopetrosis. Exploitation of next-generation sequencing tools is ever spreading, facilitating differential diagnosis. Some complex phenotypes in which osteopetrosis is accompanied by additional clinical features have received a molecular classification, also involving new genes. Moreover, novel types of mutations have been recognized, which for their nature or genomic location are at high risk being neglected. Yet, the causative mutation is unknown in some patients, indicating that the genetics of osteopetrosis still deserves intense research efforts.
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Affiliation(s)
- Eleonora Palagano
- Humanitas Clinical and Research Institute, via Manzoni 113, 20089, Rozzano, MI, Italy
- Department of Medical Biotechnologies and Translational Medicine, University of Milan, Milan, Italy
| | - Ciro Menale
- Humanitas Clinical and Research Institute, via Manzoni 113, 20089, Rozzano, MI, Italy
- Milan Unit, CNR-IRGB, Milan, Italy
| | - Cristina Sobacchi
- Humanitas Clinical and Research Institute, via Manzoni 113, 20089, Rozzano, MI, Italy.
- Milan Unit, CNR-IRGB, Milan, Italy.
| | - Anna Villa
- Humanitas Clinical and Research Institute, via Manzoni 113, 20089, Rozzano, MI, Italy
- Milan Unit, CNR-IRGB, Milan, Italy
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