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Zhao T, Xu S, Liu S, Xu J, Zhang X, Zhan Y. Fahr's disease linked to a novel mutation in MYORG variants manifesting as paroxysmal limb stiffness and dysarthria: Case report and literature review. Mol Genet Genomic Med 2023; 11:e2276. [PMID: 37680026 PMCID: PMC10724521 DOI: 10.1002/mgg3.2276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 07/24/2023] [Accepted: 08/17/2023] [Indexed: 09/09/2023] Open
Abstract
BACKGROUND Primary familial brain calcification (PFBC) is a rare hereditary neurodegenerative disorder associated with the MYORG gene; however, the clinical and radiological characteristics of MYORG-PFBC remain unclear. METHODS We present relevant medical data obtained from a patient affected by PFBC with a novel MYORG variant and conducted a mutational analysis of MYORG in her family members. We reviewed all reported PFBC cases with biallelic MYORG mutations until April 1, 2023, and summarized the associated clinical and radiological features and mutation sites. RESULTS The patient (22-year-old woman) exhibited paroxysmal limb stiffness and dysarthria for 3 years. Computed tomography revealed calcifications in the paraventricular white matter, basal ganglia, thalamus, and cerebellum. Whole-exome sequencing revealed a novel homozygous frameshift variant (c.743delG: p.G248Afs*32) in exon 2 of the MYORG gene (NM_020702.5). To date, 62 families and 64 mutation sites have been reported. Among the reported biallelic MYORG mutations, 57% were homozygous and 43% were compound heterozygous. Individuals with biallelic MYORG mutations experience more severe brain calcification with approximately 100% clinical penetrance. Ten single heterozygous mutation sites are associated with significant brain calcifications. CONCLUSION All patients with primary brain calcification, particularly younger patients without a family history of the disease, should be screened for MYORG mutations.
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Affiliation(s)
- Tianxue Zhao
- Department of Endocrinology, Affiliated Hangzhou First People's HospitalZhejiang University School of MedicineHangzhouChina
| | - Shaokun Xu
- Department of GeriatricsZhejiang Provincial People's HospitalHangzhouChina
| | - Siyue Liu
- Department of Endocrinology, Affiliated Hangzhou First People's HospitalZhejiang University School of MedicineHangzhouChina
| | - Juan Xu
- Department of Endocrinology, Affiliated Hangzhou First People's HospitalZhejiang University School of MedicineHangzhouChina
| | - Xianfeng Zhang
- Department of Endocrinology, Affiliated Hangzhou First People's HospitalZhejiang University School of MedicineHangzhouChina
| | - Yuhong Zhan
- Department of Endocrinology, Affiliated Hangzhou First People's HospitalZhejiang University School of MedicineHangzhouChina
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Chen SY, Ho CJ, Lu YT, Lin CH, Lan MY, Tsai MH. The Genetics of Primary Familial Brain Calcification: A Literature Review. Int J Mol Sci 2023; 24:10886. [PMID: 37446066 DOI: 10.3390/ijms241310886] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 06/21/2023] [Accepted: 06/22/2023] [Indexed: 07/15/2023] Open
Abstract
Primary familial brain calcification (PFBC), also known as Fahr's disease, is a rare inherited disorder characterized by bilateral calcification in the basal ganglia according to neuroimaging. Other brain regions, such as the thalamus, cerebellum, and subcortical white matter, can also be affected. Among the diverse clinical phenotypes, the most common manifestations are movement disorders, cognitive deficits, and psychiatric disturbances. Although patients with PFBC always exhibit brain calcification, nearly one-third of cases remain clinically asymptomatic. Due to advances in the genetics of PFBC, the diagnostic criteria of PFBC may need to be modified. Hitherto, seven genes have been associated with PFBC, including four dominant inherited genes (SLC20A2, PDGFRB, PDGFB, and XPR1) and three recessive inherited genes (MYORG, JAM2, and CMPK2). Nevertheless, around 50% of patients with PFBC do not have pathogenic variants in these genes, and further PFBC-associated genes are waiting to be identified. The function of currently known genes suggests that PFBC could be caused by the dysfunction of the neurovascular unit, the dysregulation of phosphate homeostasis, or mitochondrial dysfunction. An improved understanding of the underlying pathogenic mechanisms for PFBC may facilitate the development of novel therapies.
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Affiliation(s)
- Shih-Ying Chen
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Kaohsiung 833401, Taiwan
| | - Chen-Jui Ho
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Kaohsiung 833401, Taiwan
| | - Yan-Ting Lu
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Kaohsiung 833401, Taiwan
| | - Chih-Hsiang Lin
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Kaohsiung 833401, Taiwan
| | - Min-Yu Lan
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Kaohsiung 833401, Taiwan
- Center for Parkinson's Disease, Kaohsiung Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Kaohsiung 833401, Taiwan
- Center for Mitochondrial Research and Medicine, Kaohsiung Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Kaohsiung 833401, Taiwan
| | - Meng-Han Tsai
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Kaohsiung 833401, Taiwan
- School of Medicine, College of Medicine, Chang Gung University, Taoyuan 333323, Taiwan
- Department of Medical Research, Kaohsiung Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Kaohsiung 833401, Taiwan
- Genomics and Proteomics Core Laboratory, Kaohsiung Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Kaohsiung 833401, Taiwan
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Song T, Zhao Y, Wen G, Du J, Xu Q. A novel MYORG mutation causes primary familial brain calcification with migraine: Case report and literature review. Front Neurol 2023; 14:1110227. [PMID: 36816548 PMCID: PMC9932805 DOI: 10.3389/fneur.2023.1110227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 01/13/2023] [Indexed: 02/05/2023] Open
Abstract
Primary familial brain calcification (PFBC) is a disorder in which pathologic calcification of the basal ganglia, cerebellum, or other brain regions with bilateral symmetry occurs. Common clinical symptoms include dysarthria, cerebellar symptoms, motor deficits, and cognitive impairment. Genetic factors are an important cause of the disease; however autosomal recessive (AR) inheritance is rare. In 2018, the myogenesis-regulated glycosidase (MYORG) gene was the first to be associated with AR-PFBC. The present case is a 24-year-old woman with AR-PFBC that presented with migraine at the age of 16 years. Symmetrical patchy calcifications were seen in the bilateral cerebellopontine nuclei, thalamus, basal ganglia, and radiocoronal area on computed tomography and magnetic resonance imaging. AR-PFBC with migraine as the main clinical symptom is rare. Whole-exome sequencing revealed a compound heterozygous mutation in the MYORG gene, one of which has not been previously reported. Our case highlights the pathogenic profile of the MYORG gene, and demonstrates the need for exclusion of calcium deposits in the brain for migraine patients with AR inheritance.
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Affiliation(s)
- Tingwei Song
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Yuwen Zhao
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, China,Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, China
| | - Guo Wen
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, China
| | - Juan Du
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, China
| | - Qian Xu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, China,Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, China,*Correspondence: Qian Xu ✉
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The Pathology of Primary Familial Brain Calcification: Implications for Treatment. Neurosci Bull 2022; 39:659-674. [PMID: 36469195 PMCID: PMC10073384 DOI: 10.1007/s12264-022-00980-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 07/10/2022] [Indexed: 12/08/2022] Open
Abstract
AbstractPrimary familial brain calcification (PFBC) is an inherited neurodegenerative disorder mainly characterized by progressive calcium deposition bilaterally in the brain, accompanied by various symptoms, such as dystonia, ataxia, parkinsonism, dementia, depression, headaches, and epilepsy. Currently, the etiology of PFBC is largely unknown, and no specific prevention or treatment is available. During the past 10 years, six causative genes (SLC20A2, PDGFRB, PDGFB, XPR1, MYORG, and JAM2) have been identified in PFBC. In this review, considering mechanistic studies of these genes at the cellular level and in animals, we summarize the pathogenesis and potential preventive and therapeutic strategies for PFBC patients. Our systematic analysis suggests a classification for PFBC genetic etiology based on several characteristics, provides a summary of the known composition of brain calcification, and identifies some potential therapeutic targets for PFBC.
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Meek RW, Brockerman J, Fordwour OB, Zandberg WF, Davies GJ, Vocadlo DJ. The primary familial brain calcification-associated protein MYORG is an α-galactosidase with restricted substrate specificity. PLoS Biol 2022; 20:e3001764. [PMID: 36129849 PMCID: PMC9491548 DOI: 10.1371/journal.pbio.3001764] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 07/25/2022] [Indexed: 11/18/2022] Open
Abstract
Primary familial brain calcification (PFBC) is characterised by abnormal deposits of calcium phosphate within various regions of the brain that are associated with severe cognitive impairments, psychiatric conditions, and movement disorders. Recent studies in diverse populations have shown a link between mutations in myogenesis-regulating glycosidase (MYORG) and the development of this disease. MYORG is a member of glycoside hydrolase (GH) family 31 (GH31) and, like the other mammalian GH31 enzyme α-glucosidase II, this enzyme is found in the lumen of the endoplasmic reticulum (ER). Though presumed to act as an α-glucosidase due to its localization and sequence relatedness to α-glucosidase II, MYORG has never been shown to exhibit catalytic activity. Here, we show that MYORG is an α-galactosidase and present the high-resolution crystal structure of MYORG in complex with substrate and inhibitor. Using these structures, we map detrimental mutations that are associated with MYORG-associated brain calcification and define how these mutations may drive disease progression through loss of enzymatic activity. Finally, we also detail the thermal stabilisation of MYORG afforded by a clinically approved small molecule ligand, opening the possibility of using pharmacological chaperones to enhance the activity of mutant forms of MYORG. MYORG is an enzyme genetically linked to primary familial brain calcification that has historically been presumed to act as an α-glucosidase. This study describes the crystal structure of dimeric MYORG and, surprisingly, reveals it to be an α-galactosidase with restricted specificity.
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Affiliation(s)
- Richard W. Meek
- Department of Chemistry. University of York, York, United Kingdom
| | - Jacob Brockerman
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Osei B. Fordwour
- Department of Chemistry, Irving K. Barber Faculty of Science, University of British Columbia, Kelowna, British Columbia, Canada
| | - Wesley F. Zandberg
- Department of Chemistry, Irving K. Barber Faculty of Science, University of British Columbia, Kelowna, British Columbia, Canada
| | - Gideon J. Davies
- Department of Chemistry. University of York, York, United Kingdom
- * E-mail: (GJD); (DJV)
| | - David J. Vocadlo
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada
- * E-mail: (GJD); (DJV)
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A novel loss-of-function compound heterozygous mutation of MYORG causes idiopathic basal ganglia calcification 7. Parkinsonism Relat Disord 2022; 97:65-67. [PMID: 35334423 DOI: 10.1016/j.parkreldis.2022.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 02/26/2022] [Accepted: 03/13/2022] [Indexed: 11/23/2022]
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