1
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Bowen CJ, Jones MJ, Stein D, Fine AM, Carlston C, Lau J. Brief, Resolved, Unexplained Events Explained in a Two-Month Old Infant. J Pediatr 2024; 273:114127. [PMID: 38815744 DOI: 10.1016/j.jpeds.2024.114127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 05/06/2024] [Accepted: 05/22/2024] [Indexed: 06/01/2024]
Affiliation(s)
- Caitlin J Bowen
- Department of Pediatrics, Boston Children's Hospital, Boston, MA.
| | - Maggie J Jones
- Department of Pediatrics, Boston Children's Hospital, Boston, MA
| | - Deborah Stein
- Department of Pediatrics, Boston Children's Hospital, Boston, MA; Division of Nephrology, Boston Children's Hospital, Boston, MA
| | - Andrew M Fine
- Department of Pediatrics, Boston Children's Hospital, Boston, MA; Division of Emergency Medicine, Boston Children's Hospital, Boston, MA
| | - Colleen Carlston
- Department of Pediatrics, Boston Children's Hospital, Boston, MA; Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA
| | - Julianna Lau
- Department of Pediatrics, Boston Children's Hospital, Boston, MA
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2
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Dokurel Çetin İ, Betül Gerik-Çelebi H, Demiral M, Çetin O. Hereditary hypomagnesemia with secondary hypocalcemia caused by a novel mutation in TRPM6 gene. J Pediatr Endocrinol Metab 2024; 37:184-188. [PMID: 38084506 DOI: 10.1515/jpem-2023-0378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 11/27/2023] [Indexed: 02/09/2024]
Abstract
OBJECTIVES Hereditary hypomagnesemia with secondary hypocalcemia (HSH), which results from variations in the transient receptor potential melastatin 6 (TRPM6) genes, is a rare hereditary cause of extremely low serum magnesium levels. We describe an infant with triggered seizures due to hypomagnesemia and a novel mutation in TRPM6 gene was identified. CASE PRESENTATION A 10-month-old boy presented with multidrug resistant seizures, and axial hypotonia due to severe hypomagnesemia. Electroencephalography and neuroimaging of the patient was normal. He had a favorable outcome with magnesium supplement. In this study, the patient underwent clinical exome sequencing (CES) which detected a novel homozygous variant in the TRPM6 gene: NM_017662.5: c.5571-3C>G. After replacing his magnesium orally, he was free from seizures and had an encouraging outcome at the twelfth-month follow-up. CONCLUSIONS HSH often presents with developmental issues, treatment-resistant seizures, and increased neuromuscular excitability. Untreated hypomagnesemia can potentially be fatal and severely impair cognitive function. Clinical suspicion is essential for early diagnosis and treatment.
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Affiliation(s)
- İpek Dokurel Çetin
- Department of Pediatrics, Division of Pediatric Neurology, Balikesir University Medical Faculty, Balikesir, Türkiye
| | | | - Meliha Demiral
- Department of Pediatrics, Division of Pediatric Endocrinology, Ataturk City Hospital, Balikesir, Türkiye
| | - Orkun Çetin
- Department of Obstetrics and Gynecology, Division of Perinatology, Balikesir University Medical Faculty, Balıkesir, Türkiye
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3
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Khadse S, Takalikar VS, Ghildiyal R, Shah N. Rare cause of recurrent hypocalcaemia and functional hypoparathyroidism due to hypomagnesaemia caused by TRPM6 gene mutation. BMJ Case Rep 2024; 17:e257505. [PMID: 38413141 PMCID: PMC10900374 DOI: 10.1136/bcr-2023-257505] [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] [Indexed: 02/29/2024] Open
Abstract
Magnesium is essential for the functioning and release of parathyroid hormone. Therefore, its deficiency can present as functional hypoparathyroidism. This case report describes a rare inherited disorder called congenital hypomagnesaemia with secondary hypocalcaemia due to TRPM6 gene mutation. This disease clinically and biochemically mimics hypoparathyroidism. However, unlike hypoparathyroidism, it can be treated only by long-term oral magnesium supplements. The patient presented to us with recurrent hypocalcaemic convulsions. The laboratory picture in each admission was similar to that of hypoparathyroidism. However, the hypocalcaemia persisted, and it was noticed to be associated with persistent hypomagnesaemia. A defect in the tubular magnesium reabsorption was postulated and a genetic analysis of the patient was done, which revealed a TRPM6 mutation causing hypomagnesaemia by excessive renal excretion of magnesium. The child responded well to oral magnesium supplements and is currently developmentally appropriate for her age and thriving well.
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Affiliation(s)
- Savita Khadse
- Pediatrics, Lokmanya Tilak Municipal General Hospital and Lokmanya Tilak Municipal Medical College, Mumbai, Maharashtra, India
| | - Vrushali Satish Takalikar
- Pediatrics, Lokmanya Tilak Municipal General Hospital and Lokmanya Tilak Municipal Medical College, Mumbai, Maharashtra, India
| | - Radha Ghildiyal
- Pediatrics, Lokmanya Tilak Municipal General Hospital and Lokmanya Tilak Municipal Medical College, Mumbai, Maharashtra, India
| | - Nikhil Shah
- Pediatrics, Lokmanya Tilak Municipal General Hospital and Lokmanya Tilak Municipal Medical College, Mumbai, Maharashtra, India
- Division Of Pediatric Endocrinology, Department of Pediatrics, Surya Children's Hospital, Mumbai, India
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4
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Rios FJ, Sarafian RD, Camargo LL, Montezano AC, Touyz RM. Recent Advances in Understanding the Mechanistic Role of Transient Receptor Potential Ion Channels in Patients With Hypertension. Can J Cardiol 2023; 39:1859-1873. [PMID: 37865227 DOI: 10.1016/j.cjca.2023.10.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 10/17/2023] [Accepted: 10/17/2023] [Indexed: 10/23/2023] Open
Abstract
The transient receptor potential (TRP) channel superfamily is a group of nonselective cation channels that function as cellular sensors for a wide range of physical, chemical, and environmental stimuli. According to sequence homology, TRP channels are categorized into 6 subfamilies: TRP canonical, TRP vanilloid, TRP melastatin, TRP ankyrin, TRP mucolipin, and TRP polycystin. They are widely expressed in different cell types and tissues and have essential roles in various physiological and pathological processes by regulating the concentration of ions (Ca2+, Mg2+, Na+, and K+) and influencing intracellular signalling pathways. Human data and experimental models indicate the importance of TRP channels in vascular homeostasis and hypertension. Furthermore, TRP channels have emerged as key players in oxidative stress and inflammation, important in the pathophysiology of cardiovascular diseases, including hypertension. In this review, we present an overview of the TRP channels with a focus on their role in hypertension. In particular, we highlight mechanisms activated by TRP channels in vascular smooth muscle and endothelial cells and discuss their contribution to processes underlying vascular dysfunction in hypertension.
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Affiliation(s)
- Francisco J Rios
- Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada.
| | - Raquel D Sarafian
- Institute of Biosciences, Department of Genetics and Evolutionary Biology, University of Sao Paulo, Sao Paulo, Brazil
| | - Livia L Camargo
- Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Augusto C Montezano
- Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Rhian M Touyz
- Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada; Department of Medicine, McGill University, Montreal, Quebec, Canada.
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5
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Kamali F, Jamee M, Sayer JA, Sadeghi-Bojd S, Golchehre Z, Dehghanzad R, Keramatipour M, Mohkam M. Intestinal hypomagnesemia in an Iranian patient with a novel TRPM6 variant: a case report and review of the literature. CEN Case Rep 2023; 12:413-418. [PMID: 36967423 PMCID: PMC10620355 DOI: 10.1007/s13730-023-00785-8] [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: 09/24/2022] [Accepted: 03/13/2023] [Indexed: 03/28/2023] Open
Abstract
TRPM6 is predominantly expressed in the kidney and colon and encodes a protein containing an ion channel domain and a protein kinase domain. It is crucial for magnesium homeostasis and plays important roles in epithelial magnesium transport and the active magnesium absorption. In this study, we present a 70-day-old Iranian female patient from consanguineous parents with hypomagnesemia and secondary hypocalcemia. She presented with seizures 19 days after birth and refractory watery non-bloody diarrhea. She consequently had failure to thrive. Other features included hypotonia, wide anterior fontanel, ventriculomegaly, and pseudotumor cerebri following administration of nalidixic acid. She had severe hypomagnesemia and hypocalcemia which were treated with magnesium and calcium supplementation. Despite initial unstable response to supplemental magnesium, she eventually improved and the diarrhea discontinued. The patient was discharged by magnesium and calcium therapy. At the last follow-up at age 2.5 years, the patient remained well without any recurrence or complication. Genetic testing by whole-exome sequencing revealed a novel homozygous frameshift insertion-deletion (indel) variant in exon 26 of the TRPM6 gene, c.3693-3699del GCAAGAG ins CTGCTGTTGACATCTGCT, p.L1231Ffs*36. Segregation analysis revealed the TRPM6 heterozygous variant in both parents. Patients with biallelic TRPM6 pathogenic variants typically exhibit hypomagnesemia with secondary hypocalcemia and present with neurologic manifestations including seizures. In some patients, this is also complicated by chronic diarrhea and failure to thrive. Long-term complications are rare and most of the patients show a good prognosis with supplemental magnesium therapy.
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Affiliation(s)
- Farnaz Kamali
- Pediatric Nephrology Research Center, Research Institute for Children's Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Student Research Committee, Alborz University of Medical Sciences, Karaj, Iran
| | - Mahnaz Jamee
- Pediatric Nephrology Research Center, Research Institute for Children's Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - John A Sayer
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Central Parkway, Newcastle Upon Tyne, NE1 3BZ, UK
- Renal Services, The Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, NE7 7DN, UK
- NIHR Newcastle Biomedical Research Centre, Newcastle University, Newcastle Upon Tyne, NE45PL, Tyne and Wear, UK
| | - Simin Sadeghi-Bojd
- Genetics of Non-Communicable Disease Research Center, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Zahra Golchehre
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Reyhaneh Dehghanzad
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Keramatipour
- Watson Genetic Laboratory, North Kargar Street, Tehran, Iran.
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
| | - Masoumeh Mohkam
- Pediatric Nephrology Research Center, Research Institute for Children's Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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6
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Vydra Bousova K, Zouharova M, Jiraskova K, Vetyskova V. Interaction of Calmodulin with TRPM: An Initiator of Channel Modulation. Int J Mol Sci 2023; 24:15162. [PMID: 37894842 PMCID: PMC10607381 DOI: 10.3390/ijms242015162] [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: 08/19/2023] [Revised: 10/05/2023] [Accepted: 10/11/2023] [Indexed: 10/29/2023] Open
Abstract
Transient receptor potential melastatin (TRPM) channels, a subfamily of the TRP superfamily, constitute a diverse group of ion channels involved in mediating crucial cellular processes like calcium homeostasis. These channels exhibit complex regulation, and one of the key regulatory mechanisms involves their interaction with calmodulin (CaM), a cytosol ubiquitous calcium-binding protein. The association between TRPM channels and CaM relies on the presence of specific CaM-binding domains in the channel structure. Upon CaM binding, the channel undergoes direct and/or allosteric structural changes and triggers down- or up-stream signaling pathways. According to current knowledge, ion channel members TRPM2, TRPM3, TRPM4, and TRPM6 are directly modulated by CaM, resulting in their activation or inhibition. This review specifically focuses on the interplay between TRPM channels and CaM and summarizes the current known effects of CaM interactions and modulations on TRPM channels in cellular physiology.
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7
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Cabezas-Bratesco D, Mcgee FA, Colenso CK, Zavala K, Granata D, Carnevale V, Opazo JC, Brauchi SE. Sequence and structural conservation reveal fingerprint residues in TRP channels. eLife 2022; 11:73645. [PMID: 35686986 PMCID: PMC9242649 DOI: 10.7554/elife.73645] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 05/19/2022] [Indexed: 11/13/2022] Open
Abstract
Transient receptor potential (TRP) proteins are a large family of cation-selective channels, surpassed in variety only by voltage-gated potassium channels. Detailed molecular mechanisms governing how membrane voltage, ligand binding, or temperature can induce conformational changes promoting the open state in TRP channels are still a matter of debate. Aiming to unveil distinctive structural features common to the transmembrane domains within the TRP family, we performed phylogenetic reconstruction, sequence statistics, and structural analysis over a large set of TRP channel genes. Here, we report an exceptionally conserved set of residues. This fingerprint is composed of twelve residues localized at equivalent three-dimensional positions in TRP channels from the different subtypes. Moreover, these amino acids are arranged in three groups, connected by a set of aromatics located at the core of the transmembrane structure. We hypothesize that differences in the connectivity between these different groups of residues harbor the apparent differences in coupling strategies used by TRP subgroups.
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Affiliation(s)
| | - Francisco A Mcgee
- Department of Biology, Temple University, Philadelphia, United States
| | - Charlotte K Colenso
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | - Kattina Zavala
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Valdivia, Chile
| | - Daniele Granata
- Department of Biology, Temple University, Philadelphia, United States
| | | | - Juan C Opazo
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Valdivia, Chile
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8
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Vargas-Poussou R, Claverie-Martin F, Prot-Bertoye C, Carotti V, van der Wijst J, Perdomo-Ramirez A, Fraga-Rodriguez GM, Hureaux M, Bos C, Latta F, Houillier P, Hoenderop JGJ, de Baaij JHF. Possible role for rare TRPM7 variants in patients with hypomagnesaemia with secondary hypocalcaemia. Nephrol Dial Transplant 2022; 38:679-690. [PMID: 35561741 PMCID: PMC9976740 DOI: 10.1093/ndt/gfac182] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Hypomagnesaemia with secondary hypocal-caemia (HSH) is a rare autosomal recessive disorder caused by pathogenic variants in TRPM6, encoding the channel-kinase transient receptor potential melastatin type 6. Patients have very low serum magnesium (Mg2+) levels and suffer from muscle cramps and seizures. Despite genetic testing, a subgroup of HSH patients remains without a diagnosis. METHODS In this study, two families with an HSH phenotype but negative for TRPM6 pathogenic variants were subjected to whole exome sequencing. Using a complementary combination of biochemical and functional analyses in overexpression systems and patient-derived fibroblasts, the effect of the TRPM7-identified variants on Mg2+ transport was examined. RESULTS For the first time, variants in TRPM7 were identified in two families as a potential cause for hereditary HSH. Patients suffer from seizures and muscle cramps due to magnesium deficiency and episodes of hypocalcaemia. In the first family, a splice site variant caused the incorporation of intron 1 sequences into the TRPM7 messenger RNA and generated a premature stop codon. As a consequence, patient-derived fibroblasts exhibit decreased cell growth. In the second family, a heterozygous missense variant in the pore domain resulted in decreased TRPM7 channel activity. CONCLUSIONS We establish TRPM7 as a prime candidate gene for autosomal dominant hypomagnesaemia and secondary hypocalcaemia. Screening of unresolved patients with hypocalcaemia and secondary hypocalcaemia may further establish TRPM7 pathogenic variants as a novel Mendelian disorder.
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Affiliation(s)
| | | | | | - Valentina Carotti
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jenny van der Wijst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ana Perdomo-Ramirez
- Unidad de Investigación, Renal Tube Group, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | | | - Marguerite Hureaux
- Département de Génétique, Centre de référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Hôpital Européen Georges Pompidou, Paris, France
| | - Caro Bos
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Femke Latta
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Pascal Houillier
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, Université de Paris, CNRS, Paris, France,Department of Physiology, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Paris, France
| | - Joost G J Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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McGinn RJ, Von Stein EL, Summers Stromberg JE, Li Y. Precision medicine in epilepsy. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2022; 190:147-188. [DOI: 10.1016/bs.pmbts.2022.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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Song J, Lei J, Zhang J, Zhang A, Gan W, Zheng B, Wang C, Gong J. Case Report: A Novel Non-Canonical Splice Site Variant (c.1638+7T>C) in TRPM6 Cause Primary Homagnesemia With Secondary Hocalcemia. Front Pediatr 2022; 10:834241. [PMID: 35692977 PMCID: PMC9174589 DOI: 10.3389/fped.2022.834241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 04/11/2022] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE Primary hypomagnesemia with secondary hypocalcemia (HSH) is caused by loss-of-function mutations in the TRPM6 gene encoding the epithelial magnesium channel. It is characterized by hypomagnesemia and secondary hypocalcemia associated with neurological symptoms. Here, we aimed to investigate the genetic defects of the TRPM6 gene found in a girl from China. METHODS The genomic DNA of the proband and the parents was extracted for whole-exome sequencing. Sanger sequencing was further performed to validate the candidate variants. Subsequently, the TRPM6 gene deletion was verified by quantitative PCR (qPCR) experiment. The effect of the variant on mRNA splicing was analyzed through a minigene splice assay and reverse transcription PCR (RT-PCR) in vitro. RESULTS The proband presented with the symptoms of generalized seizures, tetany, and muscle spasms, which were refractory to anticonvulsant treatment. Phenotypic data indicated that the patient had hypomagnesemia, poor parathyroid hormone response, and resultant hypocalcemia. The trio whole-exome sequencing identified that the proband carried compound heterozygous variants in the TRPM6 gene, a paternally derived exon 6 deletion, and a maternally derived splicing variant (c.1638+7T>C) in exon 14. The minigene splice assay confirmed that the c.1638+7T>C variant resulted in exon 14 skipping, which caused the alteration of TRPM6 mRNA splicing. CONCLUSION Our results support that the compound heterozygous variants in TRPM6 are responsible for HSH in this patient. A novel pathogenic splicing variant (c.1638+7T>C) in the intron 14 disturbs the normal TRPM6 mRNA splicing, suggesting that the non-classical splice variant plays a critical role in HSH. This variant is essential for future effective genetic diagnosis.
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Affiliation(s)
- Jiayu Song
- Department of Pediatric Nephrology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Juan Lei
- Department of Pediatric Nephrology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Jianxia Zhang
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Aiqing Zhang
- Department of Pediatric Nephrology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Weihua Gan
- Department of Pediatric Nephrology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Bixia Zheng
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Chunli Wang
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Jing Gong
- Department of Pediatric Nephrology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
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11
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Han Y, Zhao Y, Wang H, Huo L. Case Report: Novel TRPM6 Mutations Cause Hereditary Hypomagnesemia With Secondary Hypocalcemia in a Chinese Family and a Literature Review. Front Pediatr 2022; 10:912524. [PMID: 35903165 PMCID: PMC9315244 DOI: 10.3389/fped.2022.912524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/14/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Hereditary hypomagnesemia with secondary hypocalcemia (HSH) is a rare autosomal recessive disease due to biallelic TRPM6 mutations. Although the reports of HSH caused by TRPM6 mutations are not very rare, the age of onset in previously reported HSH cases were <1 year. METHODS We collected and analyzed the clinical data of twin brothers with onset age over 1 year old and performed whole exome sequencing in the patients and their parents. Confirmed by Sanger sequencing, missense mutation was analyzed in silico. We also searched Pubmed, and extracted clinical data from case reports and case series with full text in English, reporting original data of patients with TRPM6 mutations. RESULTS The twin patients had canonical HSH phenotype with compound novel TRPM6 mutations, p.T87K and c.705dupT, inherited from their father and mother, respectively. T87 is a highly conserved site and T87K is predicted to cause hydrogen bond disruption. We identified 26 articles published between May 28, 2002 to December 31, 2021 which reported a total of 88 patients with TRPM6 mutation. We found that the most common clinical phenotypes were hypomagnesemia, hypocalcemia, and convulsions. However, the age of onset in HSH patients almost always occurred under 12 months old, the twin patients of our study were 18 and 26 months old at onset. CONCLUSION We identified two novel TRPM6 mutations in a Chinses family with HSH, and showed that the age of onset with c.704c-c.705(exon7)insT and c.260(exon4)C>A mutation in TRPM6 was much later than other mutations and would be much less serious.
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Affiliation(s)
- Yiran Han
- Department of Pediatrics, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yajuan Zhao
- Department of Pediatrics, Shengjing Hospital of China Medical University, Shenyang, China
| | - Hua Wang
- Department of Pediatrics, Shengjing Hospital of China Medical University, Shenyang, China
| | - Liang Huo
- Department of Pediatrics, Shengjing Hospital of China Medical University, Shenyang, China
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12
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Lei M, Wang P, Li H, Liu X, Shu J, Zhang Q, Cai C, Li D, Zhang Y. Case Report: Recurrent Hemiplegic Migraine Attacks Accompanied by Intractable Hypomagnesemia Due to a de novo TRPM7 Gene Variant. Front Pediatr 2022; 10:880242. [PMID: 35712613 PMCID: PMC9194527 DOI: 10.3389/fped.2022.880242] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 04/29/2022] [Indexed: 11/13/2022] Open
Abstract
Transient receptor potential melastatin 7 (TRPM7) is a ubiquitously expressed chanzyme comprised of a divalent cation channel permeable to calcium and magnesium and a cytosolic serine-threonine α-kinase domain. TRPM7 has a crucial role in magnesium ion homeostasis and anoxic neuronal death, which was identified as a potential non-glutamate target for hypoxic-ischemic neuronal injury. TRPM7 is implicated in ischemic stroke and hypomagnesemia in many studies, but it has not been associated with disease in the OMIM database. No clinical cases between TRPM7 gene variants and hypomagnesemia have been reported, so far. One patient with recurrent hemiplegic migraine attacks accompanied by intractable hypomagnesemia was followed up at Tianjin Children's Hospital from 2018 to 2021. We systematically summarized and analyzed the clinical manifestations, imaging features, and serum magnesium changes of the patient. Genetic analysis was performed by whole-exome sequencing and Sanger sequencing to infer the etiology of hemiplegic migraine attacks and hypomagnesemia in this patient. Gene sequencing revealed a novel heterozygous variant of the TRPM7 gene (c.2998A>G, p. Met1000Val), which has not been reported previously; this is also a de novo variant that is not inherited from his parents. We described a novel variant p. Met1000Val (c.2998A>G) located in the transmembrane region of TRPM7 protein, which is possibly crucial for the normal function of the ion channel. Our study expands the variation spectrum of the TRPM7 gene, highlights the importance of molecular genetic evaluation in patients with TRPM7 gene deficiency, and demonstrates the causal relationship between TRPM7 gene variants and disease manifestations.
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Affiliation(s)
- Meifang Lei
- Department of Neurology, Tianjin Children's Hospital (Tianjin University Children's Hospital), Tianjin, China
| | - Ping Wang
- Tianjin Pediatric Research Institute, Tianjin Children's Hospital (Tianjin University Children's Hospital), Tianjin, China.,Tianjin Key Laboratory of Birth Defects for Prevention and Treatment, Tianjin, China
| | - Hong Li
- Department of Neurology, Tianjin Children's Hospital (Tianjin University Children's Hospital), Tianjin, China
| | - Xiaojun Liu
- Department of Neurology, Tianjin Children's Hospital (Tianjin University Children's Hospital), Tianjin, China
| | - Jianbo Shu
- Tianjin Pediatric Research Institute, Tianjin Children's Hospital (Tianjin University Children's Hospital), Tianjin, China.,Tianjin Key Laboratory of Birth Defects for Prevention and Treatment, Tianjin, China
| | - Qianqian Zhang
- Department of Neurology, Tianjin Children's Hospital (Tianjin University Children's Hospital), Tianjin, China
| | - Chunquan Cai
- Tianjin Pediatric Research Institute, Tianjin Children's Hospital (Tianjin University Children's Hospital), Tianjin, China.,Tianjin Key Laboratory of Birth Defects for Prevention and Treatment, Tianjin, China.,Department of Neurosurgery, Tianjin Children's Hospital (Tianjin University Children's Hospital), Tianjin, China
| | - Dong Li
- Department of Neurology, Tianjin Children's Hospital (Tianjin University Children's Hospital), Tianjin, China
| | - Yuqin Zhang
- Department of Neurology, Tianjin Children's Hospital (Tianjin University Children's Hospital), Tianjin, China
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13
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Gazzaz N, Alghamdi M. Familial Hypomagnesemia With Secondary Hypocalcemia: A Case Report. Cureus 2021; 13:e19847. [PMID: 34963857 PMCID: PMC8702611 DOI: 10.7759/cureus.19847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2021] [Indexed: 11/07/2022] Open
Abstract
Familial hypomagnesemia with secondary hypocalcemia is a rare genetic disorder of magnesium metabolism that presents with refractory seizures during infancy. It is caused by loss-of-function mutations in the gene encoding transient receptor potential cation channel member 6 (TRPM6). Herein we report an infant who presented with refractory seizures that were brought under control by normalizing the magnesium level. Genetic analysis revealed a nonsense variant in the TRPM6 gene. Our case highlights the importance of evaluation for familial hypomagnesemia in any child with recurrent or refractory seizures.
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Affiliation(s)
- Nour Gazzaz
- Department of Pediatrics, King Abdulaziz University Faculty of Medicine, Jeddah, SAU
| | - Maha Alghamdi
- Department of Pediatrics, King Abdulaziz University Faculty of Medicine, Jeddah, SAU
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Acar S, Schlingmann KP, Nalbantoğlu Ö, Köprülü Ö, Arslan G, Özkaya B, Özkan B. A novel synonymous homozygous variant [c.2538G>A (p.Thr846Thr)] in TRPM6 in a patient with hypomagnesemia with secondary hypocalcemia. J Pediatr Endocrinol Metab 2021; 34:1481-1486. [PMID: 34261199 DOI: 10.1515/jpem-2021-0165] [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: 03/09/2021] [Accepted: 06/20/2021] [Indexed: 11/15/2022]
Abstract
OBJECTIVES Hypomagnesemia 1, intestinal (HOMG1) is characterized by neurological symptoms that occur due to hypocalcemia and hypomagnesemia and caused by mutations in the TRPM6. Most of the identified variants in TRPM6 lead to premature termination: nonsense, frameshift, deletion, and splice site mutations. CASE PRESENTATION Herein, we report a 1.5 month-old case who presented with convulsion due to hypocalcemia and hypomagnesemia in the early infancy. Sequencing of TRPM6 revealed a novel homozygous synonymous variant [c.2538G > A (p.Thr846Thr)] in the last codon of exon 19, which is most likely to affect the splicing. We report a novel homozygous synonymous variant in the TRPM6 leading to HOMG1, expanding the mutational spectrum. CONCLUSIONS Synonymous mutations that were previously considered as harmless should be evaluated at the nucleotide level, keeping in mind that they may affect splicing and cause to the disease.
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Affiliation(s)
- Sezer Acar
- Division of Pediatric Endocrinology, Dr. Behçet Uz Children's Education and Research Hospital, Izmir, Turkey
| | | | - Özlem Nalbantoğlu
- Division of Pediatric Endocrinology, Dr. Behçet Uz Children's Education and Research Hospital, Izmir, Turkey
| | - Özge Köprülü
- Division of Pediatric Endocrinology, Dr. Behçet Uz Children's Education and Research Hospital, Izmir, Turkey
| | - Gülçin Arslan
- Division of Pediatric Endocrinology, Dr. Behçet Uz Children's Education and Research Hospital, Izmir, Turkey
| | - Beyhan Özkaya
- Division of Pediatric Endocrinology, Dr. Behçet Uz Children's Education and Research Hospital, Izmir, Turkey
| | - Behzat Özkan
- Division of Pediatric Endocrinology, Dr. Behçet Uz Children's Education and Research Hospital, Izmir, Turkey
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Bayramoğlu E, Keskin M, Aycan Z, Savaş-Erdeve Ş, Çetinkaya S. Long-term Clinical Follow-up of Patients with Familial Hypomagnesemia with Secondary Hypocalcemia. J Clin Res Pediatr Endocrinol 2021; 13:300-307. [PMID: 33565749 PMCID: PMC8388043 DOI: 10.4274/jcrpe.galenos.2021.2020.0192] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
OBJECTIVE Familial hypomagnesemia with secondary hypocalcemia (HSH) is an autosomal recessive disease caused by a mutation in the transient receptor potential melastatin 6 (TRPM6) gene and is characterized by selective magnesium malabsorption. Affected cases are usually diagnosed during infancy and usually present with seizures due to hypocalcemia and hypomagnesemia. Irreversible neurological deficits and arrhythmias can be observed without appropriate treatment. The aim was to evaluate the long-term follow-up of patients with genetically confirmed HSH. METHODS A total of six patients with HSH, two of whom were siblings, were included. Age at diagnosis, clinical, laboratory and follow-up data on admission were recorded. All 39 exons of the TRPM6 gene and flanking exon-intron junctions from genomic DNA were amplified and sequenced in all cases. RESULTS The median (range) follow-up duration was 12.1 (7.6-21.7) years. All cases were diagnosed in infancy. Four different mutations, three of which had not been previously reported, were detected in the TRPM6 gene. Treatment compliance was good and there were no severe complications in the long-term follow-up of cases. However, mental retardation, specific learning difficulty and attention deficit/hyperactive disorder were observed as comorbidities. CONCLUSION Of the four different TRPM6 mutations in this small cohort, three had not been previously reported. The long-term prognosis of HSH appears to be good, given early diagnosis and good treatment compliance. This long-term follow-up and prognostic data and the three novel mutations will contribute to the published evidence concerning this rare condition, HSH, and it is hoped will prevent negative outcomes.
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Affiliation(s)
- Elvan Bayramoğlu
- University of Health Sciences Turkey, Ankara Dr. Sami Ulus Obstetrics and Gynecology and Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey,* Address for Correspondence: University of Health Sciences Turkey, Ankara Dr. Sami Ulus Obstetrics and Gynecology and Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey Phone: +90 312 305 65 13 E-mail:
| | - Melikşah Keskin
- University of Health Sciences Turkey, Ankara Dr. Sami Ulus Obstetrics and Gynecology and Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey
| | - Zehra Aycan
- University of Health Sciences Turkey, Ankara Dr. Sami Ulus Obstetrics and Gynecology and Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey
| | - Şenay Savaş-Erdeve
- University of Health Sciences Turkey, Ankara Dr. Sami Ulus Obstetrics and Gynecology and Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey
| | - Semra Çetinkaya
- University of Health Sciences Turkey, Ankara Dr. Sami Ulus Obstetrics and Gynecology and Child Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey
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Rare Inherited Hypomagnesemias — An Endocrine Case Series. Indian Pediatr 2021. [DOI: 10.1007/s13312-021-2222-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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17
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Advances in the Development of Biomarkers for Poststroke Epilepsy. BIOMED RESEARCH INTERNATIONAL 2021; 2021:5567046. [PMID: 33959658 PMCID: PMC8075663 DOI: 10.1155/2021/5567046] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 03/26/2021] [Accepted: 04/09/2021] [Indexed: 12/23/2022]
Abstract
Stroke is the main cause of acquired epilepsy in elderly people. Poststroke epilepsy (PSE) not only affects functional recovery after stroke but also brings considerable social consequences. While some factors such as cortical involvement, hemorrhagic transformation, and stroke severity are associated with increased seizure risk, so far that remains controversial. In recent years, there are an increasing number of studies on potential biomarkers of PSE as tools for diagnosing and predicting epileptic seizures. Biomarkers such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), glutamate, and S100 calcium-binding protein B (S100B) in blood are associated with the occurrence of PSE. This review is aimed at summarizing the progress on potential biomarkers of PSE.
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Yücel H, Genç Sel Ç, Kasapkara ÇS, Karacan Küçükali G, Savas-Erdeve S, Öztoprak Ü, Ceylaner S, Şenel S, Akçaboy M. Treatment Difficulties in Hypomagnesemia Secondary to the Transient Receptor Potential Melastatin 6 Gene: A Case Report with Novel Mutation. J Clin Res Pediatr Endocrinol 2021; 13:114-118. [PMID: 32302086 PMCID: PMC7947728 DOI: 10.4274/jcrpe.galenos.2020.2020.0004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Hypomagnesemia is a rare cause of seizures in childhood but should be kept in mind in recurrent and intractable seizures and hypocalcemia in communities where consanguineous marriages are common. Familial hypomagnesemia with secondary hypocalcemia is a rare genetic cause of hypomagnesemia, due to variants in the transient receptor potential melastatin 6 (TRPM6) genes. Here, a three year-old boy with a novel variant in this gene and had difficulties with enteral hypomagnesemia treatment is presented. He had recurrent seizures since two years of age and was diagnosed with epilepsy and treated with multiple antiepileptic drugs. Subsequently, he was diagnosed with rickets due to severe hypocalcemia at another center. The patient was hypotonic and neurodevelopmentally poor. The most prominent laboratory finding was of hypomagnesemia with secondary hypocalcemia. The genetic analysis revealed a novel variant in the TRPM6 gene. After parental treatment of intravenous magnesium (Mg2+) sulfate and calcium, the treatment was switched to enteral Mg2+ medications, due to persistent hypomagnesemia and the gastrointestinal side-effects, different oral preparations were used. The patient was stable on an oral maintenance dose of Mg2+ oxide with borderline blood Mg2+ levels and resolution of hypocalcemia. Hypomagnesemia is one of the causes of hypocalcemia. Enteral replacement is the key treatment but the treatment should be individualized for each patient. Normalization of hypomagnesemia is not always easy and should not be the aim of the treatment.
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Affiliation(s)
- Hüsniye Yücel
- Dr. Sami Ulus Maternity and Children’s Health and Diseases Training and Research Hospital, Clinic of Pediatrics, Ankara, Turkey
| | - Çiğdem Genç Sel
- Dr. Sami Ulus Maternity and Children’s Health and Diseases Training and Research Hospital, Clinic of Pediatric Neurology, Ankara, Turkey
| | - Çiğdem Seher Kasapkara
- Dr. Sami Ulus Maternity and Children’s Health and Diseases Training and Research Hospital, Clinic of Pediatric Metabolism, Ankara, Turkey
| | - Gülin Karacan Küçükali
- Sami Ulus Maternity and Children’s Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey
| | - Senay Savas-Erdeve
- Sami Ulus Maternity and Children’s Health and Diseases Training and Research Hospital, Clinic of Pediatric Endocrinology, Ankara, Turkey
| | - Ülkühan Öztoprak
- Dr. Sami Ulus Maternity and Children’s Health and Diseases Training and Research Hospital, Clinic of Pediatric Neurology, Ankara, Turkey
| | | | - Saliha Şenel
- Dr. Sami Ulus Maternity and Children’s Health and Diseases Training and Research Hospital, Clinic of Pediatrics, Ankara, Turkey
| | - Meltem Akçaboy
- Dr. Sami Ulus Maternity and Children’s Health and Diseases Training and Research Hospital, Clinic of Pediatrics, Ankara, Turkey,* Address for Correspondence: Dr. Sami Ulus Maternity and Children’s Health and Diseases Training and Research Hospital, Clinic of Pediatrics, Ankara, Turkey Phone: +90 312 305 60 00 E-mail:
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Song Q, Zhang Y, Bai H, Zhong L, Li X, Zhao W, Chang G, Chen G. Mineral Element Deposition and Gene Expression across Different Tissues of Cherry Valley Ducks. Animals (Basel) 2021; 11:238. [PMID: 33477854 PMCID: PMC7832843 DOI: 10.3390/ani11010238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 01/11/2021] [Accepted: 01/14/2021] [Indexed: 01/14/2023] Open
Abstract
This study was conducted to investigate the deposition of several mineral elements and the mRNA levels of mineral-related genes across different tissues of cherry valley ducks. The contents of magnesium (Mg), potassium (K), zinc (Zn), and selenium (Se) in ducks' breast muscle, thigh muscle, liver, skin, and tibia at the age of 0, 21, 35, 49, and 63 days, respectively, were measured using an atomic fluorescence spectrophotometer, while the mRNA levels of mineral-related genes were detected by qRT-PCR. The results revealed that the dynamics of Mg and K were generally similar in each tissue, with a significant positive correlation (p < 0.05). In the breast muscle, thigh muscle, and liver, the contents of almost all mineral elements reached their peak values (p < 0.05) at the age of 49 to 63 days. Interestingly, the expression of most mineral-related genes was the highest at birth (p < 0.05). In addition, there was a significant negative correlation between the expression of ATP1A1 and the deposition of K (r = -0.957, p < 0.05), and a similar result was found for the expression of ATP8 and the deposition of Zn (r = -0.905, p < 0.05). Taken together, Mg and K could be used as joint indicators for the precise breeding of the high-quality strain of cherry valley ducks, while the age of 49 to 63 days could be used as the reference for the best marketing age. In addition, ATP1A1 and ATP8 could be used as the key genes to detect K and Zn, respectively. Hence, the findings of this study can be used to improve the production and breeding efficiency of high-quality meat ducks.
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Affiliation(s)
| | | | - Hao Bai
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, The Ministry of Education of China, Yangzhou University, Yangzhou 225009, China; (Q.S.); (Y.Z.); (L.Z.); (X.L.); (W.Z.); (G.C.)
| | | | | | | | | | - Guohong Chen
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, The Ministry of Education of China, Yangzhou University, Yangzhou 225009, China; (Q.S.); (Y.Z.); (L.Z.); (X.L.); (W.Z.); (G.C.)
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Rivas VN, Magdesian KG, Fagan S, Slovis NM, Luethy D, Javsicas LH, Caserto BG, Miller AD, Dahlgren AR, Peterson J, Hales EN, Peng S, Watson KD, Khokha MK, Finno CJ. A nonsense variant in Rap Guanine Nucleotide Exchange Factor 5 (RAPGEF5) is associated with equine familial isolated hypoparathyroidism in Thoroughbred foals. PLoS Genet 2020; 16:e1009028. [PMID: 32986719 PMCID: PMC7544121 DOI: 10.1371/journal.pgen.1009028] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 10/08/2020] [Accepted: 08/05/2020] [Indexed: 11/18/2022] Open
Abstract
Idiopathic hypocalcemia in Thoroughbred (TB) foals causes tetany and seizures and is invariably fatal. Based upon the similarity of this disease with human familial hypoparathyroidism and occurrence only in the TB breed, we conducted a genetic investigation on two affected TB foals. Familial hypoparathyroidism was identified, and pedigree analysis suggested an autosomal recessive (AR) mode of inheritance. We performed whole-genome sequencing of the two foals, their unaffected dams and four unaffected, unrelated TB horses. Both homozygosity mapping and an association analysis were used to prioritize potential genetic variants. Of the 2,808 variants that significantly associated with the phenotype using an AR mode of inheritance (P<0.02) and located within a region of homozygosity, 1,507 (54%) were located in a 9.7 Mb region on chr4 (44.9-54.6 Mb). Within this region, a nonsense variant (RAPGEF5 c.2624C>A,p.Ser875*) was significantly associated with the hypoparathyroid phenotype (Pallelic = 0.008). Affected foals were homozygous for the variant, with two additional affected foals subsequently confirmed in 2019. Necropsies of all affected foals failed to identify any histologically normal parathyroid glands. Because the nonsense mutation in RAPGEF5 was near the C-terminal end of the protein, the impact on protein function was unclear. Therefore, we tested the variant in our Xenopus overexpression model and demonstrated RAPGEF5 loss-of-function. This RAPGEF5 variant represents the first genetic variant for hypoparathyroidism identified in any domestic animal species.
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Affiliation(s)
- Victor N. Rivas
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, California, United States of America
| | - K. Gary Magdesian
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, California, United States of America
| | - Sophia Fagan
- Pediatric Genomics Discovery Program, Department of Pediatrics and Genetics, Yale School of Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Nathan M. Slovis
- Hagyard Equine Medical Hospital, Lexington, Kentucky, United States of America
| | - Daniela Luethy
- Department of Clinical Studies–New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Laura H. Javsicas
- Rhinebeck Equine L.L.P., Rhinebeck, New York, United States of America
| | | | - Andrew D. Miller
- Department of Biomedical Sciences, Section of Anatomic Pathology, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - Anna R. Dahlgren
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, California, United States of America
| | - Janel Peterson
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, California, United States of America
| | - Erin N. Hales
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, California, United States of America
| | - Sichong Peng
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, California, United States of America
| | - Katherine D. Watson
- Department of Anatomic Pathology, Veterinary Medical Teaching Hospital, University of California-Davis, Davis, California, United States of America
| | - Mustafa K. Khokha
- Pediatric Genomics Discovery Program, Department of Pediatrics and Genetics, Yale School of Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Carrie J. Finno
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, California, United States of America
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21
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Lomelino-Pinheiro S, Margarida B, Lages ADS. A novel TRPM6 variant (c.3179T>A) causing familial hypomagnesemia with secondary hypocalcemia. Endocrinol Diabetes Metab Case Rep 2020; 2020:EDM200005. [PMID: 32369769 PMCID: PMC7219130 DOI: 10.1530/edm-20-0005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 04/06/2020] [Indexed: 11/24/2022] Open
Abstract
SUMMARY Familial hypomagnesemia with secondary hypocalcemia (FHSH) is a rare autosomal recessive disorder (OMIM# 602014) characterized by profound hypomagnesemia associated with hypocalcemia. It is caused by mutations in the gene encoding transient receptor potential cation channel member 6 (TRPM6). It usually presents with neurological symptoms in the first months of life. We report a case of a neonate presenting with recurrent seizures and severe hypomagnesemia. The genetic testing revealed a novel variant in the TRPM6 gene. The patient has been treated with high-dose magnesium supplementation, remaining asymptomatic and without neurological sequelae until adulthood. Early diagnosis and treatment are important to prevent irreversible neurological damage. LEARNING POINTS Loss-of-function mutations of TRPM6 are associated with FHSH. FHSH should be considered in any child with refractory hypocalcemic seizures, especially in cases with serum magnesium levels as low as 0.2 mM. Normocalcemia and relief of clinical symptoms can be assured by administration of high doses of magnesium. Untreated, the disorder may be fatal or may result in irreversible neurological damage.
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Affiliation(s)
- Sara Lomelino-Pinheiro
- Endocrinology Department, Instituto Português de Oncologia de Lisboa Francisco Gentil, Lisboa, Portugal
| | - Bastos Margarida
- Endocrinology, Diabetes and Metabolism Department, Centro Hospitalar Universitário de Coimbra, Coimbra, Portugal
| | - Adriana de Sousa Lages
- Endocrinology, Diabetes and Metabolism Department, Centro Hospitalar Universitário de Coimbra, Coimbra, Portugal
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Willows J, Al Badi M, Richardson C, Al Sinani A, Edwards N, Rice S, Sayer JA. Case Report: Investigation and molecular genetic diagnosis of familial hypomagnesaemia. F1000Res 2019; 8:666. [PMID: 31448104 PMCID: PMC6694456 DOI: 10.12688/f1000research.19006.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/22/2019] [Indexed: 11/20/2022] Open
Abstract
Genetic mutations causing familial hypomagnesaemia syndromes are well-recognised. Affected patients can present with severe symptoms of hypomagnesaemia, such as seizures or cardiac arrhythmia. We report an affected child, from a consanguineous family, who presented in the first weeks of life with seizures secondary to hypomagnesaemia, without other associated clinical features. We performed whole exome sequencing in the affected child and segregation analysis within the family, which revealed a novel homozygous missense mutation in
TRPM6, which was confirmed as a heterozygous allele in both parents and two younger siblings who had transient hypomagnesaemia. Using
in silico modelling, we provide evidence that the missense variant p.(K1098E) in
TRPM6 is pathogenic, as it disrupts stabilising TRP domain interactions. Management of familial hypomagnesaemia relies on prompt recognition, early magnesium replacement and lifelong monitoring.
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Affiliation(s)
- Jamie Willows
- Renal Services, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE7 7DN, UK
| | - Maryam Al Badi
- National Diabetes and Endocrine Center, Royal Hospital, Ministry of Health, Muscat, Oman
| | - Chloe Richardson
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Aisha Al Sinani
- National Diabetes and Endocrine Center, Royal Hospital, Ministry of Health, Muscat, Oman
| | - Noel Edwards
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Sarah Rice
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - John A Sayer
- Renal Services, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE7 7DN, UK.,Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK.,NIHR Newcastle Biomedical Research Centre, Newcastle University, Newcastle upon Tyne, NE4 5PL, UK
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Mild hypotonia and recurrent seizures in an 8-month-old boy: Answers. Pediatr Nephrol 2019; 34:1729-1731. [PMID: 30903374 DOI: 10.1007/s00467-019-04236-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 02/10/2019] [Accepted: 03/07/2019] [Indexed: 10/27/2022]
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van der Wijst J, Belge H, Bindels RJM, Devuyst O. Learning Physiology From Inherited Kidney Disorders. Physiol Rev 2019; 99:1575-1653. [PMID: 31215303 DOI: 10.1152/physrev.00008.2018] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The identification of genes causing inherited kidney diseases yielded crucial insights in the molecular basis of disease and improved our understanding of physiological processes that operate in the kidney. Monogenic kidney disorders are caused by mutations in genes coding for a large variety of proteins including receptors, channels and transporters, enzymes, transcription factors, and structural components, operating in specialized cell types that perform highly regulated homeostatic functions. Common variants in some of these genes are also associated with complex traits, as evidenced by genome-wide association studies in the general population. In this review, we discuss how the molecular genetics of inherited disorders affecting different tubular segments of the nephron improved our understanding of various transport processes and of their involvement in homeostasis, while providing novel therapeutic targets. These include inherited disorders causing a dysfunction of the proximal tubule (renal Fanconi syndrome), with emphasis on epithelial differentiation and receptor-mediated endocytosis, or affecting the reabsorption of glucose, the handling of uric acid, and the reabsorption of sodium, calcium, and magnesium along the kidney tubule.
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Affiliation(s)
- Jenny van der Wijst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - Hendrica Belge
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - Olivier Devuyst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
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Spires D, Manis AD, Staruschenko A. Ion channels and transporters in diabetic kidney disease. CURRENT TOPICS IN MEMBRANES 2019; 83:353-396. [PMID: 31196609 PMCID: PMC6815098 DOI: 10.1016/bs.ctm.2019.01.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Type 1 and 2 diabetes mellitus are major medical epidemics affecting millions of patients worldwide. Diabetes mellitus is the leading cause of diabetic kidney disease (DKD), which is the most common cause of end-stage renal disease (ESRD). DKD is associated with significant changes in renal hemodynamics and electrolyte transport. Alterations in renal ion transport triggered by pathophysiological conditions in diabetes can exacerbate hypertension, accelerate renal injury, and are integral to the development of DKD. Renal ion transporters and electrolyte homeostasis play a fundamental role in functional changes and injury to the kidney during DKD. With the large number of ion transporters involved in DKD, understanding the roles of individual transporters as well as the complex cascades through which they interact is essential in the development of effective treatments for patients suffering from this disease. This chapter aims to gather current knowledge of the major renal ion transporters with altered expression and activity under diabetic conditions, and provide a comprehensive overview of their interactions and collective functions in DKD.
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Affiliation(s)
- Denisha Spires
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Anna D Manis
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Alexander Staruschenko
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States; Clement J. Zablocki VA Medical Center, Milwaukee, WI, United States.
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Fu CY, Chen SJ, Cai NH, Liu ZH, Zhang M, Wang PC, Zhao JN. Increased risk of post-stroke epilepsy in Chinese patients with a TRPM6 polymorphism. Neurol Res 2019; 41:378-383. [PMID: 30739590 DOI: 10.1080/01616412.2019.1568755] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVES We attempted to determine whether a functional polymorphism of TRPM6 (rs2274924) is associated with susceptibility to epilepsy following ischemic stroke, and to further explore the effect of this polymorphism on serum levels of Mg2+ in post-stroke patients. METHODS We carried out a case-control study on 378 post-stroke epilepsy patients and 420 controls (stroke patients without secondary epilepsy). We used DNA sequencing to determine the genotypes of the TRPM6 rs2274924 polymorphism, and used the ion selective electrode method to measure serum levels of Mg2+. RESULTS The distribution of the CC genotype and the frequency of the C allele were significantly higher in the post-stroke epilepsy patients than in the controls (P < 0.01). With regard to the post-stroke epilepsy patients, the serum levels of Mg2+ decreased significantly in the TRPM6 rs2274924 C allele carriers compared to the rs2274924 T allele carriers. CONCLUSION The TRPM6 rs2274924 polymorphism may be associated with susceptibility to epilepsy following stroke, and the C allele may be associated with increased risk of post-stroke epilepsy. The TRPM6 rs2274924 polymorphism may also influence serum levels of Mg2+ in post-stroke epilepsy patients.
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Affiliation(s)
- Chuan-Yi Fu
- a Department of Neurosurgery, The National Key Clinic Specialty, Hainan General Hospital , Hainan Clinical Medicine Research Institution , Haikou , Hainan , P.R. China
| | - Shui-Jie Chen
- a Department of Neurosurgery, The National Key Clinic Specialty, Hainan General Hospital , Hainan Clinical Medicine Research Institution , Haikou , Hainan , P.R. China
| | - Nan-Hua Cai
- a Department of Neurosurgery, The National Key Clinic Specialty, Hainan General Hospital , Hainan Clinical Medicine Research Institution , Haikou , Hainan , P.R. China
| | - Zhao-Hui Liu
- a Department of Neurosurgery, The National Key Clinic Specialty, Hainan General Hospital , Hainan Clinical Medicine Research Institution , Haikou , Hainan , P.R. China
| | - Mao Zhang
- a Department of Neurosurgery, The National Key Clinic Specialty, Hainan General Hospital , Hainan Clinical Medicine Research Institution , Haikou , Hainan , P.R. China
| | - Peng-Cheng Wang
- a Department of Neurosurgery, The National Key Clinic Specialty, Hainan General Hospital , Hainan Clinical Medicine Research Institution , Haikou , Hainan , P.R. China
| | - Jian-Nong Zhao
- a Department of Neurosurgery, The National Key Clinic Specialty, Hainan General Hospital , Hainan Clinical Medicine Research Institution , Haikou , Hainan , P.R. China
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Azim MK, Mehnaz A, Ahmed JZ, Mujtaba G. Exome sequencing identifies a novel frameshift variant causing hypomagnesemia with secondary hypocalcemia. CEN Case Rep 2019; 8:42-47. [PMID: 30144020 PMCID: PMC6361088 DOI: 10.1007/s13730-018-0362-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 08/20/2018] [Indexed: 12/12/2022] Open
Abstract
Hypomagnesemia with secondary hypocalcemia is a rare autosomal-recessive disorder characterized by intense hypomagnesemia associated with hypocalcemia (HSH). Mutations in the TRPM6 gene, encoding the epithelial Mg2+ channel TRPM6, have been proven to be the molecular cause of this disease. This study identified causal mutations in a 2-month-old male patient of hypomagnesemia from a consanguineous marriage. Biochemical analyses indicated the diagnosis of HSH due to primary gastrointestinal loss of magnesium. Whole exome sequencing of the trio (i.e. proband and both parents) was carried out with mean coverage of > 150×. ANNOVAR was used to annotate functional consequences of genetic variation from exome sequencing data. After variant filtering and annotation, a number of single nucleotide variants (SNVs) and 2 bp deletion at exon26:c.4402_4403delCT in TRPM6 gene were identified. This deletion which resulted in a novel frameshift mutation in exon 26 of this gene was confirmed by Sanger sequencing. With these investigations in hand, the patient was managed with magnesium sulphate. The patient remained asymptomatic and was developmentally and neurologically normal till his last follow up.
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Affiliation(s)
- M Kamran Azim
- International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan.
- Department of Biosciences, Mohammad Ali Jinnah University, Karachi, Pakistan.
| | - Aisha Mehnaz
- Department of Paediatrics, Dow Medical College, Dow University of Health Sciences, Karachi, Pakistan
| | - Javeria Z Ahmed
- Department of Paediatrics, Dow Medical College, Dow University of Health Sciences, Karachi, Pakistan
| | - Ghulam Mujtaba
- International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
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Schäffers OJM, Hoenderop JGJ, Bindels RJM, de Baaij JHF. The rise and fall of novel renal magnesium transporters. Am J Physiol Renal Physiol 2018; 314:F1027-F1033. [DOI: 10.1152/ajprenal.00634.2017] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Body Mg2+ balance is finely regulated in the distal convoluted tubule (DCT), where a tight interplay among transcellular reabsorption, mitochondrial exchange, and basolateral extrusion takes place. In the last decades, several research groups have aimed to identify the molecular players in these processes. A multitude of proteins have been proposed to function as Mg2+ transporter in eukaryotes based on phylogenetic analysis, differential gene expression, and overexpression studies. However, functional evidence for many of these proteins is lacking. The aim of this review is, therefore, to critically reconsider all putative Mg2+ transporters and put their presumed function in context of the renal handling of Mg2+. Sufficient experimental evidence exists to acknowledge transient receptor potential melastatin (TRPM) 6 and TRPM7, solute carrier family 41 (SLC41) A1 and SLC41A3, and mitochondrial RNA splicing 2 (MRS2) as Mg2+ transporters. TRPM6/7 facilitate Mg2+ influx, SLC41A1 mediates Mg2+ extrusion, and MRS2 and SLC41A3 are implicated in mitochondrial Mg2+ homeostasis. These proteins are highly expressed in the DCT. The function of cyclin M (CNNM) proteins is still under debate. For the other proposed Mg2+ transporters including Mg2+ transporter subtype 1 (MagT1), nonimprinted in Prader-Willi/Angelman syndrome (NIPA), membrane Mg2+ transport (MMgT), Huntingtin-interacting protein 14 (HIP14), and ATP13A4, functional evidence is limited, or functions alternative to Mg2+ transport have been suggested. Additional characterization of their Mg2+ transport proficiency should be provided before further claims about their role as Mg2+ transporter can be made.
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Affiliation(s)
- Olivier J. M. Schäffers
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G. J. Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - René J. M. Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jeroen H. F. de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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29
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Larsson SC, Burgess S, Michaëlsson K. Serum magnesium levels and risk of coronary artery disease: Mendelian randomisation study. BMC Med 2018; 16:68. [PMID: 29769070 PMCID: PMC5956816 DOI: 10.1186/s12916-018-1065-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 04/26/2018] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Observational studies have shown that serum magnesium levels are inversely associated with risk of cardiovascular disease, but whether this association is causal is unknown. We conducted a Mendelian randomisation study to investigate whether serum magnesium levels may be causally associated with coronary artery disease (CAD). METHODS This Mendelian randomisation analysis is based on summary-level data from the CARDIoGRAMplusC4D consortium's 1000 Genomes-based genome-wide association meta-analysis of 48 studies with a total of 60,801 CAD cases and 123,504 non-cases. Six single-nucleotide polymorphisms associated with serum magnesium levels at genome-wide significance were used as instrumental variables. RESULTS A genetic predisposition to higher serum magnesium levels was inversely associated with CAD. In conventional Mendelian randomisation analysis, the odds ratio of CAD was 0.88 (95% confidence interval [CI] 0.78 to 0.99; P = 0.03) per 0.1-mmol/L (about 1 standard deviation) increase in genetically predicted serum magnesium levels. Results were consistent in sensitivity analyses using the weighted median and heterogeneity-penalised model averaging methods, with odds ratios of 0.84 (95% CI 0.72 to 0.98; P = 0.03) and 0.83 (95% CI 0.71 to 0.96; P = 0.02), respectively. CONCLUSIONS This study based on genetics provides evidence that serum magnesium levels are inversely associated with risk of CAD. Randomised controlled trials elucidating whether magnesium supplementation lowers the risk of CAD, preferably in a setting at higher risk of hypomagnesaemia, are warranted.
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Affiliation(s)
- Susanna C Larsson
- Unit of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, 171 77, Stockholm, Sweden.
| | - Stephen Burgess
- MRC Biostatistics Unit, University of Cambridge, Cambridge, UK.,Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK
| | - Karl Michaëlsson
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
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30
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31
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Li H, Sun S, Chen J, Xu G, Wang H, Qian Q. Genetics of Magnesium Disorders. KIDNEY DISEASES 2017; 3:85-97. [PMID: 29344503 DOI: 10.1159/000477730] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 05/23/2017] [Indexed: 12/30/2022]
Abstract
Background Magnesium (Mg2+), the second most abundant cation in the cell, is woven into a multitude of cellular functions. Dysmagnesemia is associated with multiple diseases and, when severe, can be life-threatening. Summary This review discusses Mg2+ homeostasis and function with specific focus on renal Mg2+ handling. Intrarenal channels and transporters related to Mg2+ absorption are discussed. Unraveling the rare genetic diseases with manifestations of dysmagnesemia has greatly increased our understanding of the complex and intricate regulatory network in the kidney, specifically, functions of tight junction proteins including claudin-14, -16, -19, and -10; apical ion channels including: TRPM6, Kv1.1, and ROMK; small regulatory proteins including AC3 and ANK3; and basolateral proteins including EGF receptor, γ-subunit (FXYD2) of Na-K-ATPase, Kir4.1, CaSR, CNNM2, and SLC41A. Although our understanding of Mg2+ handling of the kidney has expanded considerably in the last two decades, many questions remain. Future studies are needed to elucidate a multitude of unknown aspects of Mg2+ handling in the kidney. Key Message Understanding rare and genetic diseases of Mg2+ dysregulation has expanded our knowledge and furthers the development of strategies for preventing and managing dysmagnesemia.
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Affiliation(s)
- Heng Li
- Kidney Disease Center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Shiren Sun
- Department of Nephrology, Xijing Hospital, The Fourth Military Medical University, Xian, China
| | - Jianghua Chen
- Kidney Disease Center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Goushuang Xu
- Department of Nephrology, Xijing Hospital, The Fourth Military Medical University, Xian, China
| | - Hanmin Wang
- Department of Nephrology, Xijing Hospital, The Fourth Military Medical University, Xian, China
| | - Qi Qian
- Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
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32
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Horinouchi T, Nozu K, Kamiyoshi N, Kamei K, Togawa H, Shima Y, Urahama Y, Yamamura T, Minamikawa S, Nakanishi K, Fujimura J, Morioka I, Ninchoji T, Kaito H, Nakanishi K, Iijima K. Diagnostic strategy for inherited hypomagnesemia. Clin Exp Nephrol 2017; 21:1003-1010. [DOI: 10.1007/s10157-017-1396-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 02/16/2017] [Indexed: 12/01/2022]
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33
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Mass Spectrometric Analysis of TRPM6 and TRPM7 Phosphorylation Reveals Regulatory Mechanisms of the Channel-Kinases. Sci Rep 2017; 7:42739. [PMID: 28220887 PMCID: PMC5318989 DOI: 10.1038/srep42739] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 01/12/2017] [Indexed: 01/23/2023] Open
Abstract
TRPM7 and TRPM6 were the first identified bifunctional channels to contain their own kinase domains, but how these channel-kinases are regulated is poorly understood. Previous studies identified numerous phosphorylation sites on TRPM7, but very little is known about TRPM6 phosphorylation or sites on TRPM7 transphosphorylated by TRPM6. Our mass spectrometric analysis of homomeric and heteromeric TRPM7 and TRPM6 channels identified phosphorylation sites on both proteins, as well as several prominent sites on TRPM7 that are commonly modified through autophosphorylation and transphosphorylation by TRPM6. We conducted a series of amino acid substitution analyses and identified S1777, in TRPM7’s catalytic domain, and S1565, in TRPM7’s exchange domain that mediates kinase dimerization, as potential regulatory sites. The phosphomimetic S1777D substitution disrupted catalytic activity, most likely by causing an electrostatic perturbation at the active site. The S1565D phosphomimetic substitution also inactivated the kinase but did so without interfering with kinase dimerization. Molecular modeling indicates that phosphorylation of S1565 is predicted to structurally affect TRPM7’s functionally conserved N/D loop, which is thought to influence the access of substrate to the active site pocket. We propose that phosphorylation of S1565 within the exchange domain functions as a regulatory switch to control TRPM7 catalytic activity.
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34
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Patel S, Rayanagoudar G, Gelding S. Familial hypomagnesaemia with secondary hypocalcaemia. BMJ Case Rep 2016; 2016:bcr-2016-216870. [PMID: 27624449 DOI: 10.1136/bcr-2016-216870] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Magnesium is the second most abundant intracellular cation and plays an essential role in neuronal, skeletal and cardiac tissue. Hypomagnesaemia can cause hypocalcaemia by inhibiting parathyroid hormone release and inducing resistance at its receptor sites. Untreated hypomagnesaemia can lead to tetany, recurrent seizures, status epilepticus and life-threatening arrhythmias. Primary hypomagnesaemia with secondary hypocalcaemia (HSH) is a rare metabolic disorder of intestinal magnesium absorption. The condition typically presents in the neonatal period with neuromuscular excitability and seizures refractory to antiepileptic therapy. Early diagnosis and prompt magnesium replacement are essential to prevent death or long-term neurodevelopmental sequelae. Fewer than a hundred cases are reported in the literature. Recent advances have added significantly to our understanding of the genetic basis of HSH. We report the presentation and long-term follow-up of an affected female who was found to have a mutation in the transient receptor potential melastatin 6 (TRPM6) gene, encoding a transient receptor potential cation channel.
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Affiliation(s)
- Sabina Patel
- Department of Endocrinology, Barts Health NHS Trust, London, UK
| | | | - Susan Gelding
- Department of Endocrinology, Barts Health NHS Trust, London, UK
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35
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Bardet C, Courson F, Wu Y, Khaddam M, Salmon B, Ribes S, Thumfart J, Yamaguti PM, Rochefort GY, Figueres ML, Breiderhoff T, Garcia-Castaño A, Vallée B, Le Denmat D, Baroukh B, Guilbert T, Schmitt A, Massé JM, Bazin D, Lorenz G, Morawietz M, Hou J, Carvalho-Lobato P, Manzanares MC, Fricain JC, Talmud D, Demontis R, Neves F, Zenaty D, Berdal A, Kiesow A, Petzold M, Menashi S, Linglart A, Acevedo AC, Vargas-Poussou R, Müller D, Houillier P, Chaussain C. Claudin-16 Deficiency Impairs Tight Junction Function in Ameloblasts, Leading to Abnormal Enamel Formation. J Bone Miner Res 2016; 31:498-513. [PMID: 26426912 DOI: 10.1002/jbmr.2726] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 09/28/2015] [Accepted: 09/29/2015] [Indexed: 12/26/2022]
Abstract
Claudin-16 protein (CLDN16) is a component of tight junctions (TJ) with a restrictive distribution so far demonstrated mainly in the kidney. Here, we demonstrate the expression of CLDN16 also in the tooth germ and show that claudin-16 gene (CLDN16) mutations result in amelogenesis imperfecta (AI) in the 5 studied patients with familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC). To investigate the role of CLDN16 in tooth formation, we studied a murine model of FHHNC and showed that CLDN16 deficiency led to altered secretory ameloblast TJ structure, lowering of extracellular pH in the forming enamel matrix, and abnormal enamel matrix protein processing, resulting in an enamel phenotype closely resembling human AI. This study unravels an association of FHHNC owing to CLDN16 mutations with AI, which is directly related to the loss of function of CLDN16 during amelogenesis. Overall, this study indicates for the first time the importance of a TJ protein in tooth formation and underlines the need to establish a specific dental follow-up for these patients.
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Affiliation(s)
- Claire Bardet
- EA 2496, Laboratory Orofacial Pathologies, Imaging and Biotherapies, Dental School Paris Descartes University, Sorbonne Paris Cité, France
| | - Frédéric Courson
- Department of Odontology, AP-HP, and Reference Center for Rare Diseases of the Metabolism of Calcium and Phosphorus, Nord Val de Seine Hospital, Bretonneau, France
| | - Yong Wu
- EA 2496, Laboratory Orofacial Pathologies, Imaging and Biotherapies, Dental School Paris Descartes University, Sorbonne Paris Cité, France.,Department of Oral and Cranio-maxillofacial Science, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Mayssam Khaddam
- EA 2496, Laboratory Orofacial Pathologies, Imaging and Biotherapies, Dental School Paris Descartes University, Sorbonne Paris Cité, France
| | - Benjamin Salmon
- EA 2496, Laboratory Orofacial Pathologies, Imaging and Biotherapies, Dental School Paris Descartes University, Sorbonne Paris Cité, France.,Department of Odontology, AP-HP, and Reference Center for Rare Diseases of the Metabolism of Calcium and Phosphorus, Nord Val de Seine Hospital, Bretonneau, France
| | - Sandy Ribes
- EA 2496, Laboratory Orofacial Pathologies, Imaging and Biotherapies, Dental School Paris Descartes University, Sorbonne Paris Cité, France
| | - Julia Thumfart
- Department of Pediatric Nephrology, Charité University School of Medicine, Berlin, Germany
| | - Paulo M Yamaguti
- Division of Dentistry, Oral Care Center for Inherited Diseases, University Hospital of Brasilia, Faculty of Health Sciences, University of Brasilia (UnB), Brasilia, Brazil
| | - Gael Y Rochefort
- EA 2496, Laboratory Orofacial Pathologies, Imaging and Biotherapies, Dental School Paris Descartes University, Sorbonne Paris Cité, France
| | - Marie-Lucile Figueres
- INSERM UMRS 1138, Cordeliers Research Center, Paris-Diderot, Pierre et Marie Curie and Paris Descartes Universities, CNRS ERL 8228, Paris, France
| | - Tilman Breiderhoff
- Department of Pediatric Nephrology, Charité University School of Medicine, Berlin, Germany
| | - Alejandro Garcia-Castaño
- Department of Genetics, AP-HP, and Reference Center of Children and Adult Renal Hereditary Diseases (MARHEA), European Hospital Georges Pompidou, Paris, France
| | - Benoit Vallée
- Laboratory CRRET, Paris-Est University, CNRS, Créteil, France
| | - Dominique Le Denmat
- EA 2496, Laboratory Orofacial Pathologies, Imaging and Biotherapies, Dental School Paris Descartes University, Sorbonne Paris Cité, France
| | - Brigitte Baroukh
- EA 2496, Laboratory Orofacial Pathologies, Imaging and Biotherapies, Dental School Paris Descartes University, Sorbonne Paris Cité, France
| | - Thomas Guilbert
- Cochin Institute, Plate-Forme d'Imagerie Photonique, INSERM U1016, CNRS UMR8104, Paris Descartes University Sorbonne Paris Cité, Paris, France
| | - Alain Schmitt
- Cochin Institute, Transmission Electron Microscopy Platform, INSERM U1016, CNRS UMR8104, Paris Descartes University Sorbonne Paris Cité, Paris, France
| | - Jean-Marc Massé
- Cochin Institute, Transmission Electron Microscopy Platform, INSERM U1016, CNRS UMR8104, Paris Descartes University Sorbonne Paris Cité, Paris, France
| | - Dominique Bazin
- Laboratoire de Physique des Solides, CNRS, Paris Sud University, Orsay, and LCMCP-UPMC, Collège de France, Paris, France
| | - Georg Lorenz
- Fraunhofer Institute for Mechanics of Materials IWM, Halle, Germany
| | - Maria Morawietz
- Fraunhofer Institute for Mechanics of Materials IWM, Halle, Germany
| | - Jianghui Hou
- Division of Renal Diseases, Washington University School of Medicine, St. Louis, MO, USA
| | - Patricia Carvalho-Lobato
- Human Anatomy and Embryology, Health University of Barcelona Campus-Bellvitge, University of Barcelona, Barcelona, Spain
| | - Maria Cristina Manzanares
- Human Anatomy and Embryology, Health University of Barcelona Campus-Bellvitge, University of Barcelona, Barcelona, Spain
| | - Jean-Christophe Fricain
- CHU Bordeaux, Dental School, U1026 Tissue Bioengineering, University of Bordeaux/Inserm, Bordeaux, France
| | - Deborah Talmud
- Department of Pediatrics, Centre Hospitalier Régional (CHR) d'Orléans, Orleans, France
| | | | - Francisco Neves
- Laboratory of Molecular Pharmacology, Faculty of Health Sciences, University of Brasilia (UNB), Brasilia, Brazil
| | - Delphine Zenaty
- Department of Pediatric Endocrinology, AP-HP, Paris Diderot University, Robert Debré Hospital, Paris, France
| | - Ariane Berdal
- INSERM UMRS 1138, Cordeliers Research Center, Paris-Diderot, Pierre et Marie Curie and Paris Descartes Universities, CNRS ERL 8228, Paris, France
| | - Andreas Kiesow
- Fraunhofer Institute for Mechanics of Materials IWM, Halle, Germany
| | - Matthias Petzold
- Fraunhofer Institute for Mechanics of Materials IWM, Halle, Germany
| | - Suzanne Menashi
- Laboratory CRRET, Paris-Est University, CNRS, Créteil, France
| | - Agnes Linglart
- Department of Pediatric Endocrinology, AP-HP, Paris Sud University, School of Medicine, and Reference Center for Rare Diseases of the Metabolism of Calcium and Phosphorus, Paris, France
| | - Ana Carolina Acevedo
- Division of Dentistry, Oral Care Center for Inherited Diseases, University Hospital of Brasilia, Faculty of Health Sciences, University of Brasilia (UnB), Brasilia, Brazil
| | - Rosa Vargas-Poussou
- Department of Genetics, AP-HP, and Reference Center of Children and Adult Renal Hereditary Diseases (MARHEA), European Hospital Georges Pompidou, Paris, France
| | - Dominik Müller
- Department of Pediatric Nephrology, Charité University School of Medicine, Berlin, Germany
| | - Pascal Houillier
- INSERM UMRS 1138, Cordeliers Research Center, Paris-Diderot, Pierre et Marie Curie and Paris Descartes Universities, CNRS ERL 8228, Paris, France.,Department of Physiology, AP-HP, and Reference Center of Children and Adult Renal Hereditary Diseases (MARHEA), Georges Pompidou European Hospital, Paris, France
| | - Catherine Chaussain
- EA 2496, Laboratory Orofacial Pathologies, Imaging and Biotherapies, Dental School Paris Descartes University, Sorbonne Paris Cité, France.,Department of Odontology, AP-HP, and Reference Center for Rare Diseases of the Metabolism of Calcium and Phosphorus, Nord Val de Seine Hospital, Bretonneau, France
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Altıncık A, Schlingmann KP, Tosun MS. A Novel Homozygous Mutation in the Transient Receptor Potential Melastatin 6 Gene: A Case Report. J Clin Res Pediatr Endocrinol 2016; 8:101-4. [PMID: 26759217 PMCID: PMC4805040 DOI: 10.4274/jcrpe.2254] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Hereditary hypomagnesemia with secondary hypocalcemia (HSH) is a rare autosomal recessive disease caused by mutations in the transient receptor potential melastatin 6 (TRPM6) gene. Affected individuals present in early infancy with seizures caused by the severe hypocalcemia and hypomagnesemia. By presenting this case report, we also aimed to highlight the need for molecular genetic analysis in inbred or familial cases with hypomagnesemia. A Turkish inbred girl, now aged six years, had presented to another hospital at age two months with seizures diagnosed to be due to hypomagnesemia. She was on magnesium replacement therapy when she was admitted to our clinic with complaints of chronic diarrhea at age 3.6 years. During her follow-up in our clinic, she showed an age-appropriate physical and neurological development. In molecular genetic analysis, a novel homozygous frame-shift mutation (c.3447delT>p.F1149fs) was identified in the TRPM6 gene. This mutation leads to a truncation of the TRPM6 protein, thereby complete loss of function. We present the clinical follow-up findings of a pediatric HSH case due to a novel mutation in the TRPM6 gene and highlight the need for molecular genetic analysis in inbred or familial cases with hypomagnesemia.
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Affiliation(s)
- Ayça Altıncık
- Denizli State Hospital, Clinic of Pediatric Endocrinology, Denizli, Turkey, E-mail: ,
| | | | - Mahya Sultan Tosun
- Denizli State Hospital, Clinic of Pediatric Gastroenterology, Denizli, Turkey
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37
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Chen BB, Prasad C, Kobrzynski M, Campbell C, Filler G. Seizures Related to Hypomagnesemia: A Case Series and Review of the Literature. Child Neurol Open 2016; 3:2329048X16674834. [PMID: 28503619 PMCID: PMC5417264 DOI: 10.1177/2329048x16674834] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Revised: 09/13/2016] [Accepted: 09/22/2016] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Childhood seizures have various nonneurological etiologies. The patient's magnesium levels should be measured when evaluating afebrile seizures. The purpose of the current case series is to describe a systematic approach for diagnosing hypomagnesemia using 3 recent patient cases. METHODS This case series describes 3 patients with unprovoked hypomagnesemia-associated seizures. The authors describe the differential diagnosis, pathophysiology, and the workup of hypomagnesemia-associated seizures. RESULTS Hypomagnesemia contributed to the cause of the seizures in all 3 cases. Various causes of hypomagnesemia were investigated, including genetic etiologies. All 3 patients were maintained at a magnesium level >0.65 mmol/L, which improved or eliminated the seizures. SIGNIFICANCE Magnesium levels should always be measured when trying to determine the etiology of seizures. Hypomagnesemia and afebrile seizures should be treated with the goal of maintaining a magnesium concentration >0.65 mmol/L. Although rare, genetic causes of hypomagnesemia should be considered, once common causes of hypomagnesemia are ruled out.
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Affiliation(s)
- Becky Biqi Chen
- Department of Pediatrics, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Chitra Prasad
- Department of Pediatrics, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Children’s Health Research Institute, London, Ontario, Canada
| | - Marta Kobrzynski
- Department of Pediatrics, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Craig Campbell
- Department of Pediatrics, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Children’s Health Research Institute, London, Ontario, Canada
- Department of Epidemiology and Clinical Neurological Sciences, Western University, London, Ontario, Canada
| | - Guido Filler
- Department of Pediatrics, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Children’s Health Research Institute, London, Ontario, Canada
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
- Department of Medicine, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
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Astor MC, Løvås K, Wolff ASB, Nedrebø B, Bratland E, Steen-Johnsen J, Husebye ES. Hypomagnesemia and functional hypoparathyroidism due to novel mutations in the Mg-channel TRPM6. Endocr Connect 2015; 4:215-22. [PMID: 26273099 PMCID: PMC4566842 DOI: 10.1530/ec-15-0066] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Accepted: 08/13/2015] [Indexed: 11/26/2022]
Abstract
Primary hypomagnesemia with secondary hypocalcemia (HSH) is an autosomal recessive disorder characterized by neuromuscular symptoms in infancy due to extremely low levels of serum magnesium and moderate to severe hypocalcemia. Homozygous mutations in the magnesium transporter gene transient receptor potential cation channel member 6 (TRPM6) cause the disease. HSH can be misdiagnosed as primary hypoparathyroidism. The aim of this study was to describe the genetic, clinical and biochemical features of patients clinically diagnosed with HSH in a Norwegian cohort. Five patients in four families with clinical features of HSH were identified, including one during a national survey of hypoparathyroidism. The clinical history of the patients and their families were reviewed and gene analyses of TRPM6 performed. Four of five patients presented with generalized seizures in infancy and extremely low levels of serum magnesium accompanied by moderate hypocalcemia. Two of the patients had an older sibling who died in infancy. Four novel mutations and one large deletion in TRPM6 were identified. In one patient two linked homozygous mutations were located in exon 22 (p.F978L) and exon 23 (p.G1042V). Two families had an identical mutation in exon 25 (p.E1155X). The fourth patient had a missense mutation in exon 4 (p.H61N) combined with a large deletion in the C-terminal end of the gene. HSH is a potentially lethal condition that can be misdiagnosed as primary hypoparathyroidism. The diagnosis is easily made if serum magnesium is measured. When treated appropriately with high doses of oral magnesium supplementation, severe hypomagnesemia is uncommon and the long-term prognosis seems to be good.
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Affiliation(s)
- Marianne C Astor
- Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway
| | - Kristian Løvås
- Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway
| | - Anette S B Wolff
- Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway
| | - Bjørn Nedrebø
- Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway
| | - Eirik Bratland
- Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway
| | - Jon Steen-Johnsen
- Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway
| | - Eystein S Husebye
- Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway Department of Clinical ScienceUniversity of Bergen, Bergen, NorwayDepartment of MedicineHaukeland University Hospital, Bergen, NorwayDepartment of MedicineHaugesund Hospital, Haugesund, NorwayPediatric DepartmentTelemark County Hospital, Skien, Norway
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Lambie EJ, Bruce RD, Zielich J, Yuen SN. Novel Alleles of gon-2, a C. elegans Ortholog of Mammalian TRPM6 and TRPM7, Obtained by Genetic Reversion Screens. PLoS One 2015; 10:e0143445. [PMID: 26606136 PMCID: PMC4659536 DOI: 10.1371/journal.pone.0143445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 11/04/2015] [Indexed: 11/19/2022] Open
Abstract
TRP (Transient Receptor Potential) cation channels of the TRPM subfamily have been found to be critically important for the regulation of Mg2+ homeostasis in both protostomes (e.g., the nematode, C. elegans, and the insect, D. melanogaster) and deuterostomes (e.g., humans). Although significant progress has been made toward understanding how the activities of these channels are regulated, there are still major gaps in our understanding of the potential regulatory roles of extensive, evolutionarily conserved, regions of these proteins. The C. elegans genes, gon-2, gtl-1 and gtl-2, encode paralogous TRP cation channel proteins that are similar in sequence and function to human TRPM6 and TRPM7. We isolated fourteen revertants of the missense mutant, gon-2(q338), and these mutations affect nine different residues within GON-2. Since eight of the nine affected residues are situated within regions that have high similarity to human TRPM1,3,6 and 7, these mutations identify sections of these channels that are potentially critical for channel regulation. We also isolated a single mutant allele of gon-2 during a screen for revertants of the Mg2+-hypersensitive phenotype of gtl-2(-) mutants. This allele of gon-2 converts a serine to phenylalanine within the highly conserved TRP domain, and is antimorphic against both gon-2(+) and gtl-1(+). Interestingly, others have reported that mutation of the corresponding residue in TRPM7 to glutamate results in deregulated channel activity.
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Affiliation(s)
- Eric J. Lambie
- Department of Cell and Developmental Biology, Ludwig Maximilian University, Munich, Germany
- * E-mail:
| | - Robert D. Bruce
- Dept. of Internal Medicine, Madigan Army Medical Center, Fort Lewis-McChord, Washington, United States of America
| | - Jeffrey Zielich
- Department of Cell and Developmental Biology, Ludwig Maximilian University, Munich, Germany
| | - Sonia N. Yuen
- Department of Otolaryngology, Boston Children’s Hospital, Boston, Massachusetts, United States of America
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Tomilin V, Mamenko M, Zaika O, Pochynyuk O. Role of renal TRP channels in physiology and pathology. Semin Immunopathol 2015; 38:371-83. [PMID: 26385481 DOI: 10.1007/s00281-015-0527-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 09/04/2015] [Indexed: 01/05/2023]
Abstract
Kidneys critically contribute to the maintenance of whole-body homeostasis by governing water and electrolyte balance, controlling extracellular fluid volume, plasma osmolality, and blood pressure. Renal function is regulated by numerous systemic endocrine and local mechanical stimuli. Kidneys possess a complex network of membrane receptors, transporters, and ion channels which allows responding to this wide array of signaling inputs in an integrative manner. Transient receptor potential (TRP) channel family members with diverse modes of activation, varied permeation properties, and capability to integrate multiple downstream signals are pivotal molecular determinants of renal function all along the nephron. This review summarizes experimental data on the role of TRP channels in a healthy mammalian kidney and discusses their involvement in renal pathologies.
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Affiliation(s)
- Viktor Tomilin
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, 6431 Fannin, Houston, TX, 77030, USA.,Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russian Federation
| | - Mykola Mamenko
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, 6431 Fannin, Houston, TX, 77030, USA
| | - Oleg Zaika
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, 6431 Fannin, Houston, TX, 77030, USA
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, 6431 Fannin, Houston, TX, 77030, USA.
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Blanchard MG, Kittikulsuth W, Nair AV, de Baaij JHF, Latta F, Genzen JR, Kohan DE, Bindels RJM, Hoenderop JGJ. Regulation of Mg2+ Reabsorption and Transient Receptor Potential Melastatin Type 6 Activity by cAMP Signaling. J Am Soc Nephrol 2015; 27:804-13. [PMID: 26150606 DOI: 10.1681/asn.2014121228] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 05/21/2015] [Indexed: 01/14/2023] Open
Abstract
The transient receptor potential melastatin type 6 (TRPM6) epithelial Mg(2+) channels participate in transcellular Mg(2+) transport in the kidney and intestine. Previous reports suggested a hormonal cAMP-dependent regulation of Mg(2+) reabsorption in the kidney. The molecular details of this process are, however, unknown. Adenylate cyclase 3 (Adcy3) has been shown to colocalize with the Na(+)/Cl(-) cotransporter, a marker of the distal convoluted segment of the kidney, the principal site of TRPM6 expression. Given the critical role of TRPM6 in Mg(2+) reabsorption, an inducible kidney-specific Adcy3 deletion mouse model was characterized for blood and urinary electrolyte disturbances under a normal--and low--Mg(2+) diet. Increased urinary Mg(2+) wasting and Trpm6 mRNA levels were observed in the urine and kidney of Adcy3-deleted animals compared with wild-type controls. Serum Mg(2+) concentration was significantly lower in Adcy3-deleted animals at day 7 on the low Mg(2+) diet. Using patch clamp electrophysiology, cell surface biotinylation, and total internal reflection fluorescence live cell imaging of transfected HEK293 cells, we demonstrated that cAMP signaling rapidly potentiates TRPM6 activity by promoting TRPM6 accumulation at the plasma membrane and increasing its single-channel conductance. Comparison of electrophysiological data from cells expressing the phosphorylation-deficient S1252A or phosphomimetic S1252D TRPM6 mutants suggests that phosphorylation at this intracellular residue participates in the observed stimulation of channel activity. Altogether, these data support a physiologically relevant magnesiotropic role of cAMP signaling in the kidney by a direct stimulatory action of protein kinase A on the plasma membrane trafficking and function of TRPM6 ion channels.
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Affiliation(s)
- Maxime G Blanchard
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Anil V Nair
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands; Center for Systems Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Jeroen H F de Baaij
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Femke Latta
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jonathan R Genzen
- Department of Pathology, School of Medicine, University of Utah, Salt Lake City, Utah; and
| | | | - René J M Bindels
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G J Hoenderop
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands;
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de Baaij JHF, Hoenderop JGJ, Bindels RJM. Magnesium in man: implications for health and disease. Physiol Rev 2015; 95:1-46. [PMID: 25540137 DOI: 10.1152/physrev.00012.2014] [Citation(s) in RCA: 870] [Impact Index Per Article: 96.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Magnesium (Mg(2+)) is an essential ion to the human body, playing an instrumental role in supporting and sustaining health and life. As the second most abundant intracellular cation after potassium, it is involved in over 600 enzymatic reactions including energy metabolism and protein synthesis. Although Mg(2+) availability has been proven to be disturbed during several clinical situations, serum Mg(2+) values are not generally determined in patients. This review aims to provide an overview of the function of Mg(2+) in human health and disease. In short, Mg(2+) plays an important physiological role particularly in the brain, heart, and skeletal muscles. Moreover, Mg(2+) supplementation has been shown to be beneficial in treatment of, among others, preeclampsia, migraine, depression, coronary artery disease, and asthma. Over the last decade, several hereditary forms of hypomagnesemia have been deciphered, including mutations in transient receptor potential melastatin type 6 (TRPM6), claudin 16, and cyclin M2 (CNNM2). Recently, mutations in Mg(2+) transporter 1 (MagT1) were linked to T-cell deficiency underlining the important role of Mg(2+) in cell viability. Moreover, hypomagnesemia can be the consequence of the use of certain types of drugs, such as diuretics, epidermal growth factor receptor inhibitors, calcineurin inhibitors, and proton pump inhibitors. This review provides an extensive and comprehensive overview of Mg(2+) research over the last few decades, focusing on the regulation of Mg(2+) homeostasis in the intestine, kidney, and bone and disturbances which may result in hypomagnesemia.
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Affiliation(s)
- Jeroen H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G J Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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Abstract
PURPOSE OF REVIEW The tight control of blood magnesium (Mg) levels is of central importance for numerous physiological processes. A persistent low Mg status (hypomagnesemia) is associated with severe health risks and is involved in the pathogenesis of type 2 diabetes mellitus, osteoporosis, asthma, and heart and vascular diseases. The current view has expanded significantly as a result of the identification of novel genes and regulatory pathways involved in hypomagnesemic disorders. This review aims to give an up-to-date overview of transient receptor potential melastatin 6 (TRPM6) regulation and its role in the maintenance of Mg homeostasis. RECENT FINDINGS The epithelial Mg channel TRPM6 is considered to be the Mg entry pathway in the distal convoluted tubule of the kidney, where it functions as gatekeeper for controlling the body's Mg balance. Various factors and hormones contribute not only to the function, but also to the dysregulation of TRPM6, which has a substantial impact on renal Mg handling. Recent genetic and molecular studies have further elucidated the signaling processes of epithelial Mg transport, including their effect on the expression and function of TRPM6. SUMMARY Knowledge of TRPM6 functioning is of vital importance to decipher its role in Mg handling and will, in particular, provide a molecular basis for achieving a better understanding of Mg mal(re)absorption and hence systemic Mg balance.
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44
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Zipursky J, Macdonald EM, Hollands S, Gomes T, Mamdani MM, Paterson JM, Lathia N, Juurlink DN. Proton pump inhibitors and hospitalization with hypomagnesemia: a population-based case-control study. PLoS Med 2014; 11:e1001736. [PMID: 25268962 PMCID: PMC4181956 DOI: 10.1371/journal.pmed.1001736] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 08/12/2014] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Some evidence suggests that proton pump inhibitors (PPIs) are an under-appreciated risk factor for hypomagnesemia. Whether hospitalization with hypomagnesemia is associated with use of PPIs is unknown. METHODS AND FINDINGS We conducted a population-based case-control study of multiple health care databases in Ontario, Canada, from April 2002 to March 2012. Patients who were enrolled as cases were Ontarians aged 66 years or older hospitalized with hypomagnesemia. For each individual enrolled as a case, we identified up to four individuals as controls matched on age, sex, kidney disease, and use of various diuretic classes. Exposure to PPIs was categorized according to the most proximate prescription prior to the index date as current (within 90 days), recent (within 91 to 180 days), or remote (within 181 to 365 days). We used conditional logistic regression to estimate the odds ratio for the association of outpatient PPI use and hospitalization with hypomagnesemia. To test the specificity of our findings we examined use of histamine H2 receptor antagonists, drugs with no causal link to hypomagnesemia. We studied 366 patients hospitalized with hypomagnesemia and 1,464 matched controls. Current PPI use was associated with a 43% increased risk of hypomagnesemia (adjusted odds ratio, 1.43; 95% CI 1.06-1.93). In a stratified analysis, the risk was particularly increased among patients receiving diuretics, (adjusted odds ratio, 1.73; 95% CI 1.11-2.70) and not significant among patients not receiving diuretics (adjusted odds ratio, 1.25; 95% CI 0.81-1.91). We estimate that one excess hospitalization with hypomagnesemia will occur among 76,591 outpatients treated with a PPI for 90 days. Hospitalization with hypomagnesemia was not associated with the use of histamine H2 receptor antagonists (adjusted odds ratio 1.06; 95% CI 0.54-2.06). Limitations of this study include a lack of access to serum magnesium levels, uncertainty regarding diagnostic coding of hypomagnesemia, and generalizability of our findings to younger patients. CONCLUSIONS PPIs are associated with a small increased risk of hospitalization with hypomagnesemia among patients also receiving diuretics. Physicians should be aware of this association, particularly for patients with hypomagnesemia. Please see later in the article for the Editors' Summary.
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Affiliation(s)
- Jonathan Zipursky
- Department of Medicine, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
| | - Erin M. Macdonald
- Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
| | - Simon Hollands
- Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
| | - Tara Gomes
- Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
- Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada
- Institute of Health Policy, Management, and Evaluation, University of Toronto, Toronto, Ontario, Canada
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Muhammad M. Mamdani
- Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
- Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada
- Institute of Health Policy, Management, and Evaluation, University of Toronto, Toronto, Ontario, Canada
- Applied Health Research Centre, St. Michael's Hospital, Toronto, Ontario, Canada
- King Saud University, Riyadh, Saudi Arabia
| | - J. Michael Paterson
- Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
- Institute of Health Policy, Management, and Evaluation, University of Toronto, Toronto, Ontario, Canada
- Department of Family Medicine, McMaster University, Hamilton, Ontario, Canada, Canada
| | - Nina Lathia
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - David N. Juurlink
- Department of Medicine, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
- Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
- Institute of Health Policy, Management, and Evaluation, University of Toronto, Toronto, Ontario, Canada
- Sunnybrook Research Institute, Toronto, Ontario, Canada
- * E-mail:
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Toh JWT, Ong E, Wilson R. Hypomagnesaemia associated with long-term use of proton pump inhibitors. Gastroenterol Rep (Oxf) 2014; 3:243-53. [PMID: 25138239 PMCID: PMC4527261 DOI: 10.1093/gastro/gou054] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Accepted: 07/15/2014] [Indexed: 12/13/2022] Open
Abstract
Hypomagnesaemia and associated hypocalcaemia and hypoparathyroidism have been increasingly recognised as rare long-term side-effects of proton pump inhibitors (PPIs). The PPIs may inhibit active magnesium (Mg) absorption by interfering with transcellular transient receptor potential melastatin-6 and -7 (TRPM 6 and 7) channels. More recent cell culture studies have suggested concomitant inhibition of passive Mg absorption by omeprazole. After being treated with a range of PPIs, the four patients in our case series developed hypomagnesaemia, which responded to withdrawal of therapy and initiation of Mg replacement. Their clinical course and management demonstrate key aspects of hypomagnesaemia associated with long-term use of PPIs.
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Affiliation(s)
- James Wei Tatt Toh
- General Surgery, Liverpool Hospital, University of New South Wales, Liverpool, New South Wales, Australia,
| | - Evonne Ong
- University of New South Wales Clinical School, Liverpool, New South Wales, Australia and
| | - Robert Wilson
- Upper Gastrointestinal Surgery, Liverpool Hospital, University of New South Wales, Liverpool, New South Wales, Australia
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Kinase and channel activity of TRPM6 are co-ordinated by a dimerization motif and pocket interaction. Biochem J 2014; 460:165-75. [PMID: 24650431 PMCID: PMC4019984 DOI: 10.1042/bj20131639] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mutations in the gene that encodes the atypical channel-kinase TRPM6 (transient receptor potential melastatin 6) cause HSH (hypomagnesaemia with secondary hypocalcaemia), a disorder characterized by defective intestinal Mg2+ transport and impaired renal Mg2+ reabsorption. TRPM6, together with its homologue TRPM7, are unique proteins as they combine an ion channel domain with a C-terminally fused protein kinase domain. How TRPM6 channel and kinase activity are linked is unknown. Previous structural analysis revealed that TRPM7 possesses a non-catalytic dimerization motif preceding the kinase domain. This interacts with a dimerization pocket lying within the kinase domain. In the present study, we provide evidence that the dimerization motif in TRPM6 plays a critical role in regulating kinase activity as well as ion channel activity. We identify mutations within the TRPM6 dimerization motif (Leu1718 and Leu1721) or dimerization pocket (L1743A, Q1832K, A1836N, L1840A and L1919Q) that abolish dimerization and establish that these mutations inhibit protein kinase activity. We also demonstrate that kinase activity of a dimerization motif mutant can be restored by addition of a peptide encompassing the dimerization motif. Moreover, we observe that mutations that disrupt the dimerization motif and dimerization pocket interaction greatly diminish TRPM6 ion channel activity, in a manner that is independent of kinase activity. Finally, we analyse the impact on kinase activity of ten disease-causing missense mutations that lie outwith the protein kinase domain of TRPM6. This revealed that one mutation lying nearby the dimerization motif (S1754N), found previously to inhibit channel activity, abolished kinase activity. These results provide the first evidence that there is structural co-ordination between channel and kinase activity, which is mediated by the dimerization motif and pocket interaction. We discuss that modulation of this interaction could comprise a major regulatory mechanism by which TRPM6 function is controlled. We show that TRPM6 kinase activity is linked to channel activity. This occurs through a kinase-independent mechanism involving the dimerization motif binding to a pocket within the kinase domain. A disease-causing mutation (S1754N) lying nearby the dimerization pocket inactivates kinase activity.
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Dokuyucu R, Gogebakan B, Yumrutas O, Bozgeyik I, Gokce H, Demir T. Expressions of TRPM6 and TRPM7 and histopathological evaluation of tissues in ischemia reperfusion performed rats. Ren Fail 2014; 36:932-6. [PMID: 24679001 DOI: 10.3109/0886022x.2014.900405] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
There is very little work on the expression of TRPM6/7 in ischemia reperfusion models. In previous studies, after ischemia, reperfusion had been kept limited to 24 h, yet in our study, expressions of these channels were elucidated after its modification to 48 h to establish what kind of changes renal tissues undergo. For the current study, 20 Wistar albino rats were divided into two groups equally. Group I: control group, Group II = I/R group (60 min ischemia + 48 h reperfusion). For the mRNA analysis, right kidneys of I/R group was used as a reference in order to eliminate genetic differences. The left renal artery (I/R generated part) of I/R area was removed from all rats in the second group. Likewise, normal tissues of right renal artery were removed from all rats. Histopathologic scoring of the tissue samples were achieved semi-quantitatively according to normal tissue composition. Consequently, both TRPM6 and TRPM7 expression levels were decreased in all groups according to control groups, yet results were not counted as significant (p > 0.05). Additionally, correlation analysis confirmed these results. Also, I/R performed kidneys had more tissue damage compared to control group. To conclude, our study results suggest that TRPM6/7 expressions may be increased and after 48 h of reperfusion expression levels of these two stored to normal levels. At the same time, damages have occurred in renal tissues after ischemia. These damages were considered to be resulted from the oxidative effects as previously reported.
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Affiliation(s)
- Recep Dokuyucu
- Department of Physiology, Faculty of Medicine, Mustafa Kemal University , Hatay , Turkey
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