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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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Inden M, Kimura Y, Nishii K, Masaka T, Takase N, Tsutsui M, Ohuchi K, Kurita H, Hozumi I. Role of phosphate transporter PiT-2 in the pathogenesis of primary brain calcification. Biochem Biophys Res Commun 2023; 640:21-25. [PMID: 36495606 DOI: 10.1016/j.bbrc.2022.11.106] [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: 11/04/2022] [Accepted: 11/30/2022] [Indexed: 12/07/2022]
Abstract
Primary brain calcification (PBC), also known as idiopathic basal ganglia calcification (IBGC), primary familial brain calcification (PFBC) and so on, is a rare intractable disease characterized by abnormal mineral deposits, including mostly calcium in the basal ganglia, thalamus, and cerebellum. The causative gene of familial PBC is SLC20A2, which encodes the phosphate transporter PiT-2. Despite this knowledge, the molecular mechanism underlying SLC20A2-associated PBC remains unclear. In the present study, we investigated whether haploinsufficiency or a dominant-negative mechanism reduced Pi uptake in two PiT-2 variants (T115 M and R467X). We demonstrated that the presence of T115 M or R467X had no dominant-negative effect on Pi transport activity of wild-type (WT). In addition, the subcellular localization of R467X completely differed from that of WT, indicating that there is no interaction between R467X and WT. Conversely, T115 M and WT showed almost the same localization. Therefore, we examined the interaction between T115 M and WT using the bioluminescence resonance energy transfer (BRET) method. Although WT and T115 M interact with each other, T115 M does not inhibit WT's Pi transport activity. These results suggest that the role of SLC20A2 in the pathogenesis of PBC may involve decreased intracellular Pi uptake by a haploinsufficiency mechanism rather than a dominant-negative mechanism; agents promoting PiT-2 dimerization may be promising potential therapeutic agents for PBC.
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Affiliation(s)
- Masatoshi Inden
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan.
| | - Yuna Kimura
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan
| | - Kazuya Nishii
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan
| | - Tomohiko Masaka
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan
| | - Naoko Takase
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan
| | - Mai Tsutsui
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan
| | - Kazuki Ohuchi
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan
| | - Hisaka Kurita
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan
| | - Isao Hozumi
- Laboratory of Medical Therapeutics and Molecular Therapeutics, Department Biomedical Pharmaceutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi Gifu City, Gifu, 501-1196, Japan
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Characteristics and therapeutic potential of sodium-dependent phosphate cotransporters in relation to idiopathic basal ganglia calcification. J Pharmacol Sci 2021; 148:152-155. [PMID: 34924120 DOI: 10.1016/j.jphs.2021.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/30/2021] [Accepted: 11/08/2021] [Indexed: 12/18/2022] Open
Abstract
Type-III sodium-dependent phosphate transporters 1 and 2 (PiT 1 and PiT 2, respectively) are proteins encoded by SLC20A1 and SLC20A2, respectively. The ubiquitous distribution of SLC20A1 and SLC20A2 mRNAs in mammalian tissues supports the housekeeping maintenance and homeostasis of intracellular inorganic phosphate (Pi), which is absorbed from interstitial fluid for normal cellular functions. SLC20A2 variants have been found in patients with idiopathic basal ganglia calcification (IBGC), also known as Fahr's disease or primary familial brain calcification (PFBC). Thus, disrupted Pi homeostasis is considered one of the major factors in the pathogenic mechanism of IBGC. In this paper, among the causative genes of IBGC, we focused specifically on PiT2, and its potential for a therapeutic target of IBGC.
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Shen Y, Shu S, Ren Y, Xia W, Chen J, Dong L, Ge H, Fan S, Shi L, Peng B, Zhang X. Case Report: Two Novel Frameshift Mutations in SLC20A2 and One Novel Splice Donor Mutation in PDGFB Associated With Primary Familial Brain Calcification. Front Genet 2021; 12:643452. [PMID: 34025715 PMCID: PMC8138311 DOI: 10.3389/fgene.2021.643452] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 04/08/2021] [Indexed: 12/14/2022] Open
Abstract
Primary familial brain calcification (PFBC, OMIM#213600), also known as Fahr's disease, is characterized by bilateral and symmetric brain calcification in the basal ganglia (globus pallidus, caudate nucleus, and putamen), thalamus, subcortical white matter, and cerebellum. PFBC can be caused by loss-of-function mutations in any of the six known causative genes. The most common clinical manifestations include movement disorders, cognitive impairment, and neuropsychiatric signs that gradually emerge in middle-aged patients. To broaden the PFBC mutation spectrum, we examined nine members of a family with PFBC and two sporadic cases from clinical departments, and sequenced all PFBC-causative genes in the index case. Two novel frameshift mutations in SLC20A2 [NM_001257180.2; c.806delC, p.(Pro269Glnfs*49) and c.1154delG, p.(Ser385Ilefs*70)] and one novel splice donor site mutation (NM_002608.4, c.456+1G>C, r.436_456del) in PDGFB were identified in the patient cohort. c.806delC co-segregated with brain calcification and led to SLC20A2 haploinsufficiency among the affected family members. The c.456+1G>C mutation in PDGFB resulted in aberrant mRNA splicing, thereby forming mature transcripts containing an in-frame 21 base pair (bp) deletion, which might create a stably truncated protein [p.(Val146_Gln152del)] and exert a dominant negative effect on wild-type PDGFB. All three mutations were located in highly conserved regions among multiple species and predicted to be pathogenic, as evaluated by at least eight common genetic variation scoring systems. This study identified three novel mutations in SLC20A2 and PDGFB, which broadened and enriched the PFBC mutation spectrum.
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Affiliation(s)
- Yuqi Shen
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS&PUMC), Beijing, China
| | - Shi Shu
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS&PUMC), Beijing, China.,Department of Neurology, Peking Union Medical College Hospital (PUMCH), CAMS&PUMC, Beijing, China
| | - Yaqiong Ren
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS&PUMC), Beijing, China
| | - Weibo Xia
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, PUMCH, CAMS&PUMC, Beijing, China
| | - Jianhua Chen
- Department of Neurology, Peking Union Medical College Hospital (PUMCH), CAMS&PUMC, Beijing, China
| | - Liling Dong
- Department of Neurology, Peking Union Medical College Hospital (PUMCH), CAMS&PUMC, Beijing, China
| | - Haijun Ge
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS&PUMC), Beijing, China
| | - Shiqi Fan
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS&PUMC), Beijing, China
| | - Lei Shi
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS&PUMC), Beijing, China.,National Health Commission (NHC) and CAMS Key Laboratory of Molecular Probe and Targeted Theranostics, Harbin Medical University, Harbin, China
| | - Bin Peng
- Department of Neurology, Peking Union Medical College Hospital (PUMCH), CAMS&PUMC, Beijing, China
| | - Xue Zhang
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS&PUMC), Beijing, China.,National Health Commission (NHC) and CAMS Key Laboratory of Molecular Probe and Targeted Theranostics, Harbin Medical University, Harbin, China
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Ren Y, Shen Y, Si N, Fan S, Zhang Y, Xu W, Shi L, Zhang X. Slc20a2-Deficient Mice Exhibit Multisystem Abnormalities and Impaired Spatial Learning Memory and Sensorimotor Gating but Normal Motor Coordination Abilities. Front Genet 2021; 12:639935. [PMID: 33889180 PMCID: PMC8056086 DOI: 10.3389/fgene.2021.639935] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 03/03/2021] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Primary familial brain calcification (PFBC, OMIM#213600), also known as Fahr's disease, is a rare autosomal dominant or recessive neurodegenerative disorder characterized by bilateral and symmetrical microvascular calcifications affecting multiple brain regions, particularly the basal ganglia (globus pallidus, caudate nucleus, and putamen) and thalamus. The most common clinical manifestations include cognitive impairment, neuropsychiatric signs, and movement disorders. Loss-of-function mutations in SLC20A2 are the major genetic causes of PFBC. OBJECTIVE This study aimed to investigate whether Slc20a2 knockout mice could recapitulate the dynamic processes and patterns of brain calcification and neurological symptoms in patients with PFBC. We comprehensively evaluated brain calcifications and PFBC-related behavioral abnormalities in Slc20a2-deficient mice. METHODS Brain calcifications were analyzed using classic calcium-phosphate staining methods. The Morris water maze, Y-maze, and fear conditioning paradigms were used to evaluate long-term spatial learning memory, working memory, and episodic memory, respectively. Sensorimotor gating was mainly assessed using the prepulse inhibition of the startle reflex program. Spontaneous locomotor activity and motor coordination abilities were evaluated using the spontaneous activity chamber, cylinder test, accelerating rotor-rod, and narrowing balance beam tests. RESULTS Slc20a2 homozygous knockout (Slc20a2-HO) mice showed congenital and global developmental delay, lean body mass, skeletal malformation, and a high proportion of unilateral or bilateral eye defects. Brain calcifications were detected in the hypothalamus, ventral thalamus, and midbrain early at postnatal day 80 in Slc20a2-HO mice, but were seldom found in Slc20a2 heterozygous knockout (Slc20a2-HE) mice, even at extremely old age. Slc20a2-HO mice exhibited spatial learning memory impairments and sensorimotor gating deficits while exhibiting normal working and episodic memories. The general locomotor activity, motor balance, and coordination abilities were not statistically different between Slc20a2-HO and wild-type mice after adjusting for body weight, which was a major confounding factor in our motor function evaluations. CONCLUSION The human PFBC-related phenotypes were highly similar to those in Slc20a2-HO mice. Therefore, Slc20a2-HO mice might be suitable for the future evaluation of neuropharmacological intervention strategies targeting cognitive and neuropsychiatric impairments.
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Affiliation(s)
- Yaqiong Ren
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Yuqi Shen
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Nuo Si
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Shiqi Fan
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
| | - Yi Zhang
- National Health Commission and Chinese Academy of Medical Sciences Key Laboratory of Molecular Probe and Targeted Theranostics, Harbin Medical University, Harbin, China
| | - Wanhai Xu
- National Health Commission and Chinese Academy of Medical Sciences Key Laboratory of Molecular Probe and Targeted Theranostics, Harbin Medical University, Harbin, China
| | - Lei Shi
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
- National Health Commission and Chinese Academy of Medical Sciences Key Laboratory of Molecular Probe and Targeted Theranostics, Harbin Medical University, Harbin, China
| | - Xue Zhang
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
- National Health Commission and Chinese Academy of Medical Sciences Key Laboratory of Molecular Probe and Targeted Theranostics, Harbin Medical University, Harbin, China
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Uno A, Tamune H, Kurita H, Hozumi I, Yamamoto N. SLC20A2-Associated Idiopathic Basal Ganglia Calcification-Related Recurrent Psychosis Response to Low-Dose Antipsychotics: A Case Report and Literature Review. Cureus 2020; 12:e12407. [PMID: 33532164 PMCID: PMC7845928 DOI: 10.7759/cureus.12407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Idiopathic basal ganglia calcification (IBGC), also known as Fahr’s disease or primary familial brain calcification, manifests as bilaterally symmetric calcifications in the brain. Clinical symptoms range from movement disorders to cognitive impairment and psychiatric symptoms. Since 2012, IBGC has been reported as an inherited disorder with several causative genes, including SLC20A2; however, the genotype-phenotype association remains unclear. Furthermore, longitudinal follow-up studies investigating the prognosis of neuropsychiatric symptoms in IBGC are lacking. A 36-year-old woman who experienced recurrent psychosis since the age of 30 years was admitted to our hospital. Her symptoms included delusions, hallucinations, disorganized speech, and grossly disorganized behavior. Cranial CT revealed calcification of the bilateral basal ganglia and dentate nucleus. The possibility of metabolic or endocrinological disorders causing secondary calcification was excluded via laboratory examinations. The genetic analysis revealed SLC20A2 mutation, and therefore, she was diagnosed with definite IBGC. At the age of 37, 42, and 43 years, similar psychosis recurred due to a decrease in medication. Each episode was relieved within one week with a low dose of risperidone (1.5-2 mg/day p.o.). Eventually, remission was maintained with risperidone (1.5 mg/day). To our knowledge, genetically confirmed case of IBGC with psychosis has been rarely reported. Recurrent psychosis can be the sole symptom of SLC20A2-associated IBGC and may be remitted with a low dose of risperidone. Literature review including eight case reports shows no superiority between medications. Although our case indicates that a low dose of antipsychotics can alleviate symptoms without any side effects and should be continued to prevent relapse in some patients with IBGC, there has been still shortage of the clinical evidence. Further longitudinal studies on genotype-phenotype associations may expedite personalized medicine for patients with IBGC.
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Affiliation(s)
- Akito Uno
- Department of Neuropsychiatry, Tokyo Metropolitan Tama Medical Center, Tokyo, JPN
| | - Hidetaka Tamune
- Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, Tokyo, JPN
| | - Hisaka Kurita
- Neurology, Gifu Pharmaceutical University, Gifu, JPN
| | - Isao Hozumi
- Neurology, Gifu Pharmaceutical University, Gifu, JPN
| | - Naoki Yamamoto
- Department of Neuropsychiatry, Tokyo Metropolitan Tama Medical Center, Tokyo, JPN
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