1
|
Buffolo F, Monticone S, Pecori A, Pieroni J, Losano I, Cavaglià G, Tetti M, Veglio F, Mulatero P. The spectrum of low-renin hypertension. Best Pract Res Clin Endocrinol Metab 2020; 34:101399. [PMID: 32147420 DOI: 10.1016/j.beem.2020.101399] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Low-renin hypertension (LRH) is a frequent condition in patients with arterial hypertension, accounting for 30% of patients. Monogenic forms can cause LRH in a minority of cases. However, in the large majority of patients, LRH is caused by the combined effects of congenital and acquired factors, comprising dietary habits. Several genetic variants have been proposed as co-factors in the pathogenesis of LRH with normal-low serum aldosterone. Emerging evidences support the hypothesis that a large proportion of LRH with normal-high serum aldosterone is associated with subclinical primary aldosteronism (PA). The recent identification of aldosterone-producing cell clusters (APCCs) as the possible cause of subclinical PA, further supported the concept of a continuous spectrum of autonomous aldosterone secretion, from subclinical forms towards overt PA. In this review we describe the main aspects of LRH, focusing on molecular basis, clinical risk profile and patients' management.
Collapse
Affiliation(s)
- Fabrizio Buffolo
- Division of Internal Medicine and Hypertension Unit, Department of Medical Sciences, University of Torino, Via Genova 3, 10126, Torino, Italy
| | - Silvia Monticone
- Division of Internal Medicine and Hypertension Unit, Department of Medical Sciences, University of Torino, Via Genova 3, 10126, Torino, Italy
| | - Alessio Pecori
- Division of Internal Medicine and Hypertension Unit, Department of Medical Sciences, University of Torino, Via Genova 3, 10126, Torino, Italy
| | - Jacopo Pieroni
- Division of Internal Medicine and Hypertension Unit, Department of Medical Sciences, University of Torino, Via Genova 3, 10126, Torino, Italy
| | - Isabel Losano
- Division of Internal Medicine and Hypertension Unit, Department of Medical Sciences, University of Torino, Via Genova 3, 10126, Torino, Italy
| | - Giovanni Cavaglià
- Division of Internal Medicine and Hypertension Unit, Department of Medical Sciences, University of Torino, Via Genova 3, 10126, Torino, Italy
| | - Martina Tetti
- Division of Internal Medicine and Hypertension Unit, Department of Medical Sciences, University of Torino, Via Genova 3, 10126, Torino, Italy
| | - Franco Veglio
- Division of Internal Medicine and Hypertension Unit, Department of Medical Sciences, University of Torino, Via Genova 3, 10126, Torino, Italy
| | - Paolo Mulatero
- Division of Internal Medicine and Hypertension Unit, Department of Medical Sciences, University of Torino, Via Genova 3, 10126, Torino, Italy.
| |
Collapse
|
2
|
Zilbermint M, Hannah-Shmouni F, Stratakis CA. Genetics of Hypertension in African Americans and Others of African Descent. Int J Mol Sci 2019; 20:ijms20051081. [PMID: 30832344 PMCID: PMC6429313 DOI: 10.3390/ijms20051081] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 02/19/2019] [Accepted: 02/21/2019] [Indexed: 02/07/2023] Open
Abstract
Hypertension is the leading cause of cardiovascular disease in the United States, affecting up to one-third of adults. When compared to other ethnic or racial groups in the United States, African Americans and other people of African descent show a higher incidence of hypertension and its related comorbidities; however, the genetics of hypertension in these populations has not been studied adequately. Several genes have been identified to play a role in the genetics of hypertension. They include genes regulating the renin-aldosterone-angiotensin system (RAAS), such as Sodium Channel Epithelial 1 Beta Subunit (SCNN1B), Armadillo Repeat Containing 5 (ARMC5), G Protein-Coupled Receptor Kinase 4 (GRK4), and Calcium Voltage-Gated Channel Subunit Alpha1 D (CACNA1D). In this review, we focus on recent genetic findings available in the public domain for potential differences between African Americans and other populations. We also cover some recent and relevant discoveries in the field of low-renin hypertension from our laboratory at the National Institutes of Health. Understanding the different genetics of hypertension among various groups is essential for effective precision-guided medical therapy of high blood pressure.
Collapse
Affiliation(s)
- Mihail Zilbermint
- Section on Endocrinology and Genetics, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, BG 31 RM 2A46, 31 Center Dr, Bethesda, MD 20892, USA.
- Division of Endocrinology, Diabetes, and Metabolism, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
- Johns Hopkins Community Physicians at Suburban Hospital, Bethesda, MD 20814, USA.
- Johns Hopkins University Carey Business School, Baltimore, MD 21202, USA.
| | - Fady Hannah-Shmouni
- Section on Endocrinology and Genetics, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, BG 31 RM 2A46, 31 Center Dr, Bethesda, MD 20892, USA.
| | - Constantine A Stratakis
- Section on Endocrinology and Genetics, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, BG 31 RM 2A46, 31 Center Dr, Bethesda, MD 20892, USA.
| |
Collapse
|
3
|
Monticone S, Losano I, Tetti M, Buffolo F, Veglio F, Mulatero P. Diagnostic approach to low-renin hypertension. Clin Endocrinol (Oxf) 2018; 89:385-396. [PMID: 29758100 DOI: 10.1111/cen.13741] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 04/25/2018] [Accepted: 05/08/2018] [Indexed: 12/16/2022]
Abstract
Renin-angiotensin-aldosterone system (RAAS) plays a crucial role in maintaining water and electrolytes homoeostasis, and its deregulation contributes to the development of arterial hypertension. Since the historical description of the "classical" RAAS, a dramatic increase in our understanding of the molecular mechanisms underlying the development of both essential and secondary hypertension has occurred. Approximatively 25% of the patients affected by arterial hypertension display low-renin levels, a definition that is largely arbitrary and depends on the investigated population and the specific characteristics of the assay. Most often, low-renin levels are expression of a physiological response to sodium-volume overload, but also a significant number of secondary hereditary or acquired conditions falls within this category. In a context of suppressed renin status, the concomitant examination of plasma aldosterone levels (which can be inappropriately elevated, within the normal range or suppressed) and plasma potassium are essential to formulate a differential diagnosis. To distinguish between the different forms of low-renin hypertension is of fundamental importance to address the patient to the proper clinical management, as each subtype requires a specific and targeted therapy. The present review will discuss the differential diagnosis of the most common medical conditions manifesting with a clinical phenotype of low-renin hypertension, enlightening the novelties in genetics of the familial forms.
Collapse
Affiliation(s)
- Silvia Monticone
- Division of Internal Medicine and Hypertension, Department of Medical Sciences, University of Torino, Torino, Italy
| | - Isabel Losano
- Division of Internal Medicine and Hypertension, Department of Medical Sciences, University of Torino, Torino, Italy
| | - Martina Tetti
- Division of Internal Medicine and Hypertension, Department of Medical Sciences, University of Torino, Torino, Italy
| | - Fabrizio Buffolo
- Division of Internal Medicine and Hypertension, Department of Medical Sciences, University of Torino, Torino, Italy
| | - Franco Veglio
- Division of Internal Medicine and Hypertension, Department of Medical Sciences, University of Torino, Torino, Italy
| | - Paolo Mulatero
- Division of Internal Medicine and Hypertension, Department of Medical Sciences, University of Torino, Torino, Italy
| |
Collapse
|
4
|
Abstract
Liddle syndrome is an inherited form of low-renin hypertension, transmitted with an autosomal dominant pattern. The molecular basis of Liddle syndrome resides in germline mutations of the SCNN1A, SCNN1B and SCNN1G genes, encoding the α, β, and γ-subunits of the epithelial Na+ channel (ENaC), respectively. To date, 31 different causative mutations have been reported in 72 families from four continents. The majority of the substitutions cause an increased expression of the channel at the distal nephron apical membrane, with subsequent enhanced renal sodium reabsorption. The most common clinical presentation of the disease is early onset hypertension, hypokalemia, metabolic alkalosis, suppressed plasma renin activity and low plasma aldosterone. Consequently, treatment of Liddle syndrome is based on the administration of ENaC blockers, amiloride and triamterene. Herein, we discuss the genetic basis, clinical presentation, diagnosis and treatment of Liddle syndrome. Finally, we report a new case in an Italian family, caused by a SCNN1B p.Pro618Leu substitution.
Collapse
|
5
|
Jones ES, Spence JD, Mcintyre AD, Nondi J, Gogo K, Akintunde A, Hackam DG, Rayner BL. High Frequency of Variants of Candidate Genes in Black Africans with Low Renin-Resistant Hypertension. Am J Hypertens 2017; 30:478-483. [PMID: 28052878 DOI: 10.1093/ajh/hpw167] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 12/05/2016] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVES Black subjects tend to retain salt and water, be more sensitive to aldosterone, and have suppression of plasma renin activity. Variants of the renal sodium channel (ENaC, SCNN1B) account for approximately 6% of resistant hypertension (RHT) in Blacks; other candidate genes may be important. METHODS Six candidate genes associated with low renin-resistant hypertension were sequenced in Black Africans from clinics in Kenya and South Africa. CYP11B2 was sequenced if the aldosterone level was high (primary aldosteronism phenotype); SCNN1B, NEDD4L, GRK4, UMOD, and NPPA genes were sequenced if the aldosterone level was low (Liddle phenotype). RESULTS There were 14 nonsynonymous variants (NSVs) of CYP11B2: 3 previously described and associated with alterations in aldosterone synthase production (R87G, V386A, and G435S). Out of 14, 9 variants were found in all 9 patients sequenced. There were 4 NSV of GRK4 (R65L, A116T, A142V, V486A): at least one was found in all 9 patients; 3 were previously described and associated with hypertension. There were 3 NSV of SCNN1B (R206Q, G442V, and R563Q); 2 previously described and 1 associated with hypertension. NPPA was found to have 1 NSV (V32M), not previously described and NEDD4L did not have any variants. UMOD had 3 NSV: D25G, L180V, and T585I. CONCLUSIONS A phenotypic approach to investigating the genetic architecture of RHT uncovered a surprisingly high yield of variants in candidate genes. These preliminary findings suggest that this novel approach may assist in understanding the genetic architecture of RHT in Blacks and explain their two fold risk of stroke.
Collapse
Affiliation(s)
- Erika S Jones
- Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa
| | - J D Spence
- Stroke Prevention & Atherosclerosis Research Centre, Robarts Research Institute, Western University, London, Canada
| | - Adam D Mcintyre
- Regional Genomics Centre, Robarts Research Institute, Western University, London, Canada
| | | | | | - Adeseye Akintunde
- Ladoke Akintola University of Technology Teaching Hospital, Ogbomoso, Oyo State, Nigeria
| | - Daniel G Hackam
- Departments of Medicine and Biostatistics and Epidemiology, Western University, London, Canada
| | - Brian L Rayner
- Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa
| |
Collapse
|
6
|
Cappuccio FP, Barbato A, Kerry SM. Hypertension, diabetes and cardiovascular risk in ethnic minorities in the UK. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/14746514030030041101] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mortality from coronary heart disease (CHD), stroke and end-stage renal failure (ESRF) is high in South Asian (Indo-Asian) migrants in the UK. This is associated with a high prevalence of diabetes and hypertension. Mortality from stroke and ESRF is also high in migrants to the UK of black African origin. However, CHD mortality is low in this group. This pattern of mortality is also associated with a high prevalence of hypertension and diabetes. Conventional risk factors, such as cigarette smoking and hypercholesterolaemia, are less prevalent in ethnic minority populations in the UK and unlikely to explain the differences seen between groups, although each risk factor is likely to contribute to the variation in vascular disease within each group.
Collapse
Affiliation(s)
- Francesco P Cappuccio
- Department of Community Health Sciences, St Georges Hospital Medical School, Cranmer Terrace, London, SW17 0RE, UK,
| | | | | |
Collapse
|
7
|
Associations of epithelial sodium channel genes with blood pressure: the GenSalt study. J Hum Hypertens 2014; 29:224-8. [PMID: 25231509 PMCID: PMC4357546 DOI: 10.1038/jhh.2014.78] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 06/25/2014] [Accepted: 07/18/2014] [Indexed: 01/19/2023]
Abstract
In order to investigate associations of SCNN1A, SCNN1G and SCNN1B genes with blood pressure (BP) in Han Chinese population, we included 2 880 participants did not use antihypertensive medication in the month prior to the baseline survey in the current analysis. Forty-four tag-SNPs in epithelial sodium channel (ENaC) genes were selected and genotyped and nine BP measurements were obtained during 3-day examination. In single-marker analyses, we identified significant associations of SCNN1A marker rs13306613 with diastolic BP (DBP) and SCNN1B marker rs12447134 with systolic BP (SBP) under codominant model after Bonferroni correction (P= 2.82×10−5 and 4.63×10−4, respectively). In addition, 5 SNPs in SCNN1G and 4 SNPs in SCNN1B achieved nominal significance for SBP, DBP or mean arterial pressure (MAP) under the additive model. For example, the minor C allele of rs5735 in SCNN1G gene was associated with decreased SBP, DBP and MAP (P=0.016, 5.41×10−3, and 4.36×10−3, respectively). Gene-based results showed significant associations of SCNN1G and SCNN1Bwith BP levels. This study suggested that ENaC genes play important roles in BP regulation in the Han Chinese population. Future studies are warranted to replicate these findings and functional studies are needed to identify true causal variants in ENaC genes.
Collapse
|
8
|
Gupta MD, Girish MP, Sikdar S, Ahuja R, Shah D, Kumar R, Rain M, Nejatizadeh A, Tyagi S, Pasha Q. β-T594M epithelial sodium channel gene polymorphism and essential hypertension in individuals of Indo-Aryan ancestry in Northern India. Indian Heart J 2014; 66:397-400. [PMID: 25173196 DOI: 10.1016/j.ihj.2014.05.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 07/31/2013] [Accepted: 05/15/2014] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND The T594M variant of the β-subunit of the sodium epithelial channel (ENaC) gene may contribute to hypertension in individuals of Indo-Aryan origin. METHODS Present study was performed to assess the role of the ENaC gene variant as an independent risk factor for hypertension in subjects of Indo-Aryan ancestry. A total of 150 patients of recently detected essential hypertension and 150 matched controls were genotyped for the T594M polymorphism of the ENaC gene by PCR-RFLP method. RESULTS β-T594M mutation was found to be non-polymorphic. There was major genotype call in both the groups i.e. cases and controls. Other phenotypic parameters like age, sex and body mass index were also similar among hypertensive patients and controls (P > 0.05). Hypertensive patients had significantly higher total cholesterol and triglycerides compared with controls (P < 0.0001). CONCLUSION These results do not suggest an important role for the T594M variant of the ENaC gene contributing to either the development or severity of hypertension in subjects of Indo-Aryan ancestry.
Collapse
Affiliation(s)
- Mohit D Gupta
- Associate Professor of Cardiology, Department of Cardiology, G.B. Pant Hospital, New Delhi, India.
| | - M P Girish
- Department of Cardiology, G.B. Pant Hospital, New Delhi, India
| | - Sunandan Sikdar
- Department of Cardiology, G.B. Pant Hospital, New Delhi, India
| | - Ramandeep Ahuja
- Department of Cardiology, G.B. Pant Hospital, New Delhi, India
| | - Dhaval Shah
- Department of Cardiology, G.B. Pant Hospital, New Delhi, India
| | - Rahul Kumar
- Functional Genomics Unit, CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | - Manjari Rain
- Functional Genomics Unit, CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | - Azim Nejatizadeh
- Research Center for Molecular Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Sanjay Tyagi
- Department of Cardiology, G.B. Pant Hospital, New Delhi, India
| | - Qadar Pasha
- Functional Genomics Unit, CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| |
Collapse
|
9
|
Genetics, genomics and other molecular approaches: example of salt-sensitive hypertension. J Hypertens 2012; 30:877-9. [PMID: 22495129 DOI: 10.1097/hjh.0b013e3283530957] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
10
|
Butterworth MB. Regulation of the epithelial sodium channel (ENaC) by membrane trafficking. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1166-77. [PMID: 20347969 DOI: 10.1016/j.bbadis.2010.03.010] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 03/15/2010] [Accepted: 03/20/2010] [Indexed: 02/07/2023]
Abstract
The epithelial Na(+) channel (ENaC) is a major regulator of salt and water reabsorption in a number of epithelial tissues. Abnormalities in ENaC function have been directly linked to several human disease states including Liddle syndrome, psuedohypoaldosteronism, and cystic fibrosis and may be implicated in salt-sensitive hypertension. ENaC activity in epithelial cells is regulated both by open probability and channel number. This review focuses on the regulation of ENaC in the cells of the kidney cortical collecting duct by trafficking and recycling. The trafficking of ENaC is discussed in the broader context of epithelial cell vesicle trafficking. Well-characterized pathways and protein interactions elucidated using epithelial model cells are discussed, and the known overlap with ENaC regulation is highlighted. In following the life of ENaC in CCD epithelial cells the apical delivery, internalization, recycling, and destruction of the channel will be discussed. While a number of pathways presented still need to be linked to ENaC regulation and many details of the regulation of ENaC trafficking remain to be elucidated, knowledge of these mechanisms may provide further insights into ENaC activity in normal and disease states.
Collapse
Affiliation(s)
- Michael B Butterworth
- Department Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, PA 15261, USA.
| |
Collapse
|
11
|
Lu M, Wang X, Wang F, Wang S, Lin R, Wang S, Wen H, Jin L. WNK4 Polymorphisms and Essential Hypertension in the Uyghur Population. Clin Exp Hypertens 2009; 31:179-85. [DOI: 10.1080/10641960802621325] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
12
|
Mutesa L, Azad AK, Verhaeghe C, Segers K, Vanbellinghen JF, Ngendahayo L, Rusingiza EK, Mutwa PR, Rulisa S, Koulischer L, Cassiman JJ, Cuppens H, Bours V. Genetic analysis of Rwandan patients with cystic fibrosis-like symptoms: identification of novel cystic fibrosis transmembrane conductance regulator and epithelial sodium channel gene variants. Chest 2008; 135:1233-1242. [PMID: 19017867 DOI: 10.1378/chest.08-2246] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND The defect in chloride and sodium transport in cystic fibrosis (CF) patients is a consequence of CF transmembrane conductance regulator (CFTR) loss of function and an abnormal interaction between CFTR and the epithelial sodium channel (ENaC). A few patients were described with CF-like symptoms, a single CFTR mutation, and an ENaC mutation. METHODS To study African patients with CF-like symptoms and to relate the disease to gene mutations of both CFTR and ENaC genes, we collected clinical data and DNA samples from 60 African patients with a CF phenotype. The CFTR gene was first analyzed in all patients by denaturing high-performance liquid chromatography followed by direct sequencing; whereas, the sodium channel non-voltage-gated 1 alpha (SCNN1A), sodium channel non-voltage-gated 1 beta (SCNN1B), and sodium channel non-voltage-gated 1 gamma (SCNN1G) subunits of the ENaC gene were analyzed by sequencing in the five patients who carried only one CF mutation. The frequency of all identified ENaC variants was established in a control group of 200 healthy individuals and in the 55 CF-like patients without any CFTR mutation. RESULTS Three CFTR mutants, including one previously undescribed missense mutation (p.A204T), and a 5T/7T variant were identified in five patients. ENaC gene sequencing in these five patients detected the following eight ENaC variants: c.72T>C and p.V573I in SCNN1A; p.V348M, p.G442V, c.1473 + 28C>T, and p.T577T in SCNN1B; and p.S212S and c.1176 + 30G>C in SCNN1G. In the 55 CF-like patients without any CFTR mutation, we identified five of these eight ENaC variants, including the frequent p.G442V polymorphism, but we did not detect the presence of the p.V348M, p.T577T, and c.1176 + 30G>C ENaC variants. Moreover, these last three ENaC variants, p.V348M, p.T577T, and c.1176 + 30G>C, were not found in the control group. CONCLUSION Our data suggest that CF-like syndrome in Africa could be associated with CFTR and ENaC mutations.
Collapse
Affiliation(s)
- Léon Mutesa
- Department of Human Genetics, Centre Hospitalier Universitaire-Sart-Tilman, Grappe Interdisciplinaire de Genoprotéomique Appliquée-Research, University of Liège, Liège, Belgium
| | - Abul Kalam Azad
- Department of Human Genetics, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Catherine Verhaeghe
- Department of Human Genetics, Centre Hospitalier Universitaire-Sart-Tilman, Grappe Interdisciplinaire de Genoprotéomique Appliquée-Research, University of Liège, Liège, Belgium
| | - Karin Segers
- Department of Human Genetics, Centre Hospitalier Universitaire-Sart-Tilman, Grappe Interdisciplinaire de Genoprotéomique Appliquée-Research, University of Liège, Liège, Belgium
| | - Jean-François Vanbellinghen
- Department of Human Genetics, Centre Hospitalier Universitaire-Sart-Tilman, Grappe Interdisciplinaire de Genoprotéomique Appliquée-Research, University of Liège, Liège, Belgium
| | - Louis Ngendahayo
- Department of Pathology, Centre Hospitalier Universitaire-Butare, National University of Rwanda, Butare, Rwanda
| | - Emmanuel Kamanzi Rusingiza
- Department of Pediatrics, Centre Hospitalier Universitaire-Kigali, National University of Rwanda, Kigali, Rwanda
| | - Philippe Rutwaza Mutwa
- Department of Pediatrics, Centre Hospitalier Universitaire-Kigali, National University of Rwanda, Kigali, Rwanda
| | - Stephen Rulisa
- Department of Pediatrics, Centre Hospitalier Universitaire-Kigali, National University of Rwanda, Kigali, Rwanda
| | - Lucien Koulischer
- Department of Human Genetics, Centre Hospitalier Universitaire-Sart-Tilman, Grappe Interdisciplinaire de Genoprotéomique Appliquée-Research, University of Liège, Liège, Belgium
| | | | - Harry Cuppens
- Department of Human Genetics, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Vincent Bours
- Department of Human Genetics, Centre Hospitalier Universitaire-Sart-Tilman, Grappe Interdisciplinaire de Genoprotéomique Appliquée-Research, University of Liège, Liège, Belgium.
| |
Collapse
|
13
|
Zhu H, Guo D, Li K, Yan W, Tan Y, Wang X, Treiber FA, Chao J, Snieder H, Dong Y. Prostasin: a possible candidate gene for human hypertension. Am J Hypertens 2008; 21:1028-33. [PMID: 18583984 DOI: 10.1038/ajh.2008.224] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Prostasin, a serine protease, is suggested to be a novel mechanism regulating the epithelial sodium channel (ENaC) expressed in the distal nephron. This study aimed to evaluate whether the human prostasin gene is a novel candidate gene underlying blood pressure (BP) elevation. METHODS In a sample of healthy African-American (AA) and European-American (EA) twin subjects aged 17.6 +/- 3.3 years (n = 920, 45% AAs), race-specific tagging single-nucleotide polymorphisms (tSNPs) were identified to tag all the available SNPs +/- 2 kb up- and downstream of the prostasin gene from HapMap at r2 of 0.8-1.0. Selection yielded four tSNPs in AAs and one in EAs, with one tSNP (rs12597511: C to T) present in both AAs and EAs. RESULTS For rs12597511, CT and TT genotypes exhibited higher systolic BP (SBP) than CC genotype (115.9 +/- 1.1 mm Hg vs. 113.7 +/- 0.6 mm Hg, P = 0.025 (AAs); and 110.7 +/- 0.5 mm Hg vs. 109.6 +/- 0.6 mm Hg, P = 0.115 (EAs)). CT and TT genotypes compared with CC genotype showed a significant increase in diastolic BP (DBP) in both racial groups (62.5 +/- 0.7 mm Hg vs. 60.4 +/- 0.4 mm Hg, P = 0.003 (AAs); and 58.2 +/- 0.3 mm Hg vs. 56.7 +/- 0.4 mm Hg, P = 0.007 (EAs)). Furthermore, there was an increase in radial pulse wave velocity (PWV) in subjects with CT and TT genotype as compared with those with CC genotype (6.5 +/- 0.1 vs. 6.1 +/- 0.1 m/s, P < 0.0001) (EAs); and 6.7 +/- 0.1 vs. 6.6 +/- 0.1 m/s, P = 0.354 (AAs)). Analyses combining AAs and EAs consistently demonstrated a statistical significance of rs12597511 on all the phenotypes including SBP/DBP and PWV. CONCLUSION Genetic variation of the prostasin gene may be implicated in the development of hypertension in youths..
Collapse
|
14
|
Sirugo G, Hennig BJ, Adeyemo AA, Matimba A, Newport MJ, Ibrahim ME, Ryckman KK, Tacconelli A, Mariani-Costantini R, Novelli G, Soodyall H, Rotimi CN, Ramesar RS, Tishkoff SA, Williams SM. Genetic studies of African populations: an overview on disease susceptibility and response to vaccines and therapeutics. Hum Genet 2008; 123:557-98. [PMID: 18512079 DOI: 10.1007/s00439-008-0511-y] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Accepted: 05/07/2008] [Indexed: 01/13/2023]
Abstract
Africa is the ultimate source of modern humans and as such harbors more genetic variation than any other continent. For this reason, studies of the patterns of genetic variation in African populations are crucial to understanding how genes affect phenotypic variation, including disease predisposition. In addition, the patterns of extant genetic variation in Africa are important for understanding how genetic variation affects infectious diseases that are a major problem in Africa, such as malaria, tuberculosis, schistosomiasis, and HIV/AIDS. Therefore, elucidating the role that genetic susceptibility to infectious diseases plays is critical to improving the health of people in Africa. It is also of note that recent and ongoing social and cultural changes in sub-Saharan Africa have increased the prevalence of non-communicable diseases that will also require genetic analyses to improve disease prevention and treatment. In this review we give special attention to many of the past and ongoing studies, emphasizing those in Sub-Saharan Africans that address the role of genetic variation in human disease.
Collapse
Affiliation(s)
- Giorgio Sirugo
- Medical Research Council Laboratories, Fajara, The Gambia, West Africa.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Abstract
Plasma renin levels can be used to classify hypertension. A significant proportion of hypertensive individuals display a low-renin profile and thus low-renin hypertension (LRH) requires appropriate diagnosis and treatment. LRH includes essential, secondary and genetic forms, the most common of which are low-renin essential hypertension and primary aldosteronism. Several studies have investigated the relationship between PRA status and clinical response to different antihypertensive therapies. The present review will discuss the differential diagnosis of LRH subtypes and the most appropriate treatment options based on the pathophysiological background of this condition.
Collapse
Affiliation(s)
- Paolo Mulatero
- Department of Medicine and Experimental Oncology, Division of Internal Medicine and Hypertension, University of Torino, Italy.
| | | | | | | |
Collapse
|
16
|
Hollier JM, Martin DF, Bell DM, Li JL, Chirachanchai MG, Menon DV, Leonard D, Wu X, Cooper RS, McKenzie C, Victor RG, Auchus RJ. Epithelial sodium channel allele T594M is not associated with blood pressure or blood pressure response to amiloride. Hypertension 2006; 47:428-33. [PMID: 16432044 DOI: 10.1161/01.hyp.0000200704.45994.ff] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Accepted: 12/06/2005] [Indexed: 11/16/2022]
Abstract
The T594M allele of the epithelial sodium channel beta-subunit has been proposed as a gain-of-function mutation leading to salt-sensitive hypertension in blacks that is particularly responsive to the specific sodium channel antagonist amiloride. However, the positive associations derive from small convenience samples, and the amiloride challenge study lacked a control group. We determined whether the T594M allele was associated with hypertension and blood pressure (BP) response to amiloride in 2 well-characterized random population samples including 3137 Dallas County subjects and 1666 Jamaican blacks. In multivariate models, the T594M allele was not predictive of systolic BP (adjusted odds ratio for hypertension 1.1; 95% confidence interval, 0.7 to 1.8). Amiloride treatment did not lower the BP of 6 T594M heterozygotes significantly more than in 22 control subjects (P=0.8). We conclude that the T594M allele does not contribute significantly to BP in blacks and does not predict a significantly superior response to amiloride therapy.
Collapse
Affiliation(s)
- John M Hollier
- Division of Hypertension, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-8857, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Hannila-Handelberg T, Kontula K, Tikkanen I, Tikkanen T, Fyhrquist F, Helin K, Fodstad H, Piippo K, Miettinen HE, Virtamo J, Krusius T, Sarna S, Gautschi I, Schild L, Hiltunen TP. Common variants of the beta and gamma subunits of the epithelial sodium channel and their relation to plasma renin and aldosterone levels in essential hypertension. BMC MEDICAL GENETICS 2005; 6:4. [PMID: 15661075 PMCID: PMC547905 DOI: 10.1186/1471-2350-6-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2004] [Accepted: 01/20/2005] [Indexed: 11/25/2022]
Abstract
Background Rare mutations of the epithelial sodium channel (ENaC) result in the monogenic hypertension form of Liddle's syndrome. We decided to screen for common variants in the ENaC βand γ subunits in patients with essential hypertension and to relate their occurrence to the activity of circulating renin-angiotensin-aldosterone system. Methods Initially, DNA samples from 27 patients with low renin/low aldosterone hypertension were examined. The DNA variants were subsequently screened for in 347 patients with treatment-resistant hypertension, 175 male subjects with documented long-lasting normotension and 301 healthy
Plasma renin and aldosterone levels were measured under baseline conditions and during postural and captopril challenge tests. Results Two commonly occurring βENaC variants (G589S and a novel intronic i12-17CT substitution) and one novel γENaC variant (V546I) were detected. One of these variants occurred in a heterozygous form in 32 patients, a prevalence (9.2%) significantly higher than that in normotensive males (2.9%, p = 0.007) and blood donors (3.0%, p = 0.001). βENaC i12-17CT was significantly more prevalent in the hypertension group than in the two control groups combined (4.6% vs. 1.1%, p = 0.001). When expressed in Xenopus oocytes, neither of the two ENaC amino acid-changing variants showed a significant difference in activity compared with ENaC wild-type. No direct evidence for a mRNA splicing defect could be obtained for the βENaC intronic variant. The ratio of daily urinary potassium excretion to upright and mean (of supine and upright values) plasma renin activity was higher in variant allele carriers than in non-carriers (p = 0.034 and p = 0.048). Conclusions At least 9% of Finnish patients with hypertension admitted to a specialized center carry genetic variants of β and γENaC, a three times higher prevalence than in the normotensive individuals or in random healthy controls. Patients with the variant alleles showed an increased urinary potassium excretion rate in relation to their renin levels.
Collapse
Affiliation(s)
- Tuula Hannila-Handelberg
- Department of Medicine, University of Helsinki, and Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland
| | - Kimmo Kontula
- Department of Medicine, University of Helsinki, and Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland
| | - Ilkka Tikkanen
- Department of Medicine, University of Helsinki, and Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland
| | - Tuula Tikkanen
- Department of Medicine, University of Helsinki, and Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland
| | - Frej Fyhrquist
- Department of Medicine, University of Helsinki, and Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland
| | - Karri Helin
- Department of Medicine, University of Helsinki, and Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland
| | - Heidi Fodstad
- Department of Medicine, University of Helsinki, and Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland
| | - Kirsi Piippo
- Department of Medicine, University of Helsinki, and Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland
| | - Helena E Miettinen
- Department of Medicine, University of Helsinki, and Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland
| | - Jarmo Virtamo
- Department of Epidemiology and Health Promotion, National Public Health Institute, 00300 Helsinki, Finland
| | - Tom Krusius
- The Finnish Red Cross Blood Service, 00310 Helsinki, Finland
| | - Seppo Sarna
- Department of Public Health, University of Helsinki, 00014 Helsinki, Finland
| | - Ivan Gautschi
- Institute of Pharmacology and Toxicology, University of Lausanne, 1005 Lausanne, Switzerland
| | - Laurent Schild
- Institute of Pharmacology and Toxicology, University of Lausanne, 1005 Lausanne, Switzerland
| | - Timo P Hiltunen
- Department of Medicine, University of Helsinki, and Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland
- Helsinki University Central Hospital, Jorvi Hospital, 02740 Espoo, Finland
| |
Collapse
|
18
|
Siani A, Russo P, Paolo Cappuccio F, Iacone R, Venezia A, Russo O, Barba G, Iacoviello L, Strazzullo P. Combination of renin-angiotensin system polymorphisms is associated with altered renal sodium handling and hypertension. Hypertension 2004; 43:598-602. [PMID: 14967847 DOI: 10.1161/01.hyp.0000117985.57001.b3] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Genes of the renin-angiotensin-aldosterone system (RAAS) are natural candidates for sodium homeostasis and blood pressure regulation. To investigate the effect of a combination of polymorphisms of RAAS genes on renal sodium handling and blood pressure, 918 participants to the Olivetti Heart Study were genotyped for the following polymorphisms: I/D of angiotensin converting enzyme (ACE), M235T of angiotensinogen (AGT), A1166C of angiotensin II type-1 receptor (AT1R), and C-344T of aldosterone synthase (CYP11B2). The segmental renal sodium handling was evaluated by the fractional excretions of exogenous lithium (FE-Li), uric acid (FE-UA), and sodium (FE-Na). Twenty-eight carriers of triple homozygosity for M (AGT), A (AT1R), and C (CYP11B2) in the presence of the D allele of ACE (DD/ID) showed lower FE-Li (20.0%+/-5.9% versus 25.0%+/-7.5%; P=0.004; mean+/-sD), FE-UA (6.3%+/-2.0% versus 8.2%+/-2.7%; P=0.001), and FE-Na (0.96%+/-0.41% versus 1.22%+/-0.61%; P=0.004) as compared with all other allelic combinations (n=890), independently from age and body mass, suggesting an enhanced rate of proximal tubular sodium reabsorption. The carriers of the MM, AA, CC, DD/ID combination showed a substantially higher probability of being hypertensive (OR: 3.4 [(99% CI: 1.1 to 10.1]), independently of age and body mass. This relatively rare combination of allelic variants of candidate genes of the RAAS is associated with a significant alteration in proximal renal sodium handling and with higher risk of hypertension, suggesting that a combination of polymorphic variants at different candidate loci may affect phenotypic expression even in the absence of detectable effects of each variant at any single locus.
Collapse
Affiliation(s)
- Alfonso Siani
- Institute of Food Sciences, CNR, Via Roma, 52 A/C, 83100 Avellino, Italy.
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Barbato A, Cappuccio FP, Folkerd EJ, Strazzullo P, Sampson B, Cook DG, Alberti KGMM. Metabolic syndrome and renal sodium handling in three ethnic groups living in England. Diabetologia 2004; 47:40-6. [PMID: 14618235 DOI: 10.1007/s00125-003-1260-z] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2003] [Revised: 09/03/2003] [Indexed: 11/29/2022]
Abstract
AIM/HYPOTHESIS Increased proximal renal sodium re-absorption is associated with central adiposity and insulin resistance in white men. Our study examined whether this association also exists in other ethnic groups with different prevalences of insulin resistance and associated metabolic abnormalities. METHODS We studied the association between fractional renal excretion of endogenous lithium (FELi) and metabolic syndrome in a population study of 1190 randomly selected men and women who where 40 to 59 years of age (426 white, 397 of African and 367 of South Asian origin). Anthropometric values, blood pressure, biochemical values, questionnaire data and timed urine collections were obtained with standardised techniques. Endogenous lithium in serum and urine was measured by absorption spectrophotometry. Metabolic markers were the homeostasis model assessment (HOMA) index, waist circumference, serum triglycerides, serum HDL cholesterol and metabolic syndrome as defined by Adult Treatment Panel III criteria. RESULTS In white men and women a higher rate of proximal sodium re-absorption was inversely associated with higher waist circumference, serum triglycerides and HOMA index, and with lower serum HDL cholesterol (all p< or =0.001). No associations were found in people of African or South Asian origin. The former had lower FELi than the other groups. White people with the metabolic syndrome had a lower FELi than those without (15.9% vs 19.0%; p=0.003). No difference was found in people of African or South Asian origin. CONCLUSIONS/INTERPRETATION Increased proximal sodium re-absorption is associated with the metabolic syndrome in white men and women. This relationship is not seen in people of African or South Asian origin, despite a greater degree of insulin resistance.
Collapse
Affiliation(s)
- A Barbato
- Department of Community Health Sciences, St George's Hospital Medical School, Cranmer Terrace, SW17 0RE, London, UK
| | | | | | | | | | | | | |
Collapse
|
20
|
Kamide K, Tanaka C, Takiuchi S, Miwa Y, Yoshii M, Horio T, Kawano Y, Miyata T. Six Missense Mutations of the Epithelial Sodium Channel .BETA. and .GAMMA. Subunits in Japanese Hypertensives. Hypertens Res 2004; 27:333-8. [PMID: 15198480 DOI: 10.1291/hypres.27.333] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Liddle's syndrome is an autosomal dominant disease characterized by sodium-sensitive early hypertension and mutations in either the beta- or gamma-subunit of the amiloride-sensitive epithelial sodium channel encoded by SCNN1B and SCNN1G. We sequenced the 381 bp-coding regions in exon 13 of SCNN1B and the 381 bp-coding regions in exon 12 of SCNN1G in 948 and 953 Japanese patients with hypertension, respectively. In the SCNN1B gene, we identified three missense mutations, P592S (n=3), T594M (n=2), and E632K (n=1) in a heterozygous state in addition to four synonymous ones, Ile515 (n=1), Ser520 (n=19), Ser533 (n=1), and Thr594 (n=11). In the SCNN1G gene, we identified three missense mutations, A578V (n=1), P603S (n=1), and L609F (n=1) in a heterozygous state in addition to two synonymous ones, Ile550 (n=1) and Leu649 (n= 91, heterozygous; n=2, homozygous). We did not identify the same mutations previously reported in Liddle's syndrome kindreds. Two of the six hypertensive patients with missense mutation in the SCNN1B gene showed atypical renin and aldosterone levels, though one of them was diagnosed with renovascular hypertension. One patient with T594M in the SCNN1B gene was resistant to hypertension. The roles of these missense mutations in the SCNN1B or SCNN1G gene identified in hypertensive patients are not clear in the pathogenesis of hypertension and the regulation of electrolytes. Thus, further investigation of these mutations, including functional analyses, will be needed.
Collapse
Affiliation(s)
- Kei Kamide
- Division of Hypertension and Nephrology, National Cardiovascular Center, Suita, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Swift PA, Macgregor GA. Genetic variation in the epithelial sodium channel: a risk factor for hypertension in people of african origin. ACTA ACUST UNITED AC 2004; 11:76-86. [PMID: 14730541 DOI: 10.1053/j.arrt.2003.10.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
High blood pressure occurs commonly in individuals of African origin, leading to an increased risk of cardiovascular and end-stage renal disease (ESRD). Black individuals frequently have low plasma renin activity, and their blood pressure responds well to salt reduction, suggesting that abnormalities in renal sodium handling may be important in the etiology of hypertension in this population. The epithelial sodium channel (ENaC) has a central role in sodium transport across membranes, and in the kidney it contributes to the regulation of blood pressure via changes in sodium balance and blood volume. Rare monogenetic disorders have been described in association with hypertension, such as Liddle's syndrome. In addition, other ENaC polymorphisms have also been described, some of which are more common in black individuals. The T594M polymorphism of ENaC occurs exclusively in black individuals and is associated with hypertension in a black South London population. There is preliminary evidence that amiloride is effective as monotherapy in hypertensives with the T594M polymorphism, and a further study is underway to determine whether this is indeed a safe and specific treatment. If so, then amiloride may provide an important new strategy for blood pressure control in affected black hypertensives.
Collapse
Affiliation(s)
- Pauline A Swift
- Blood Pressure Unit, St. George's Hospital Medical School, Cranmer Terrace, London, SW17 0RE, UK.
| | | |
Collapse
|
22
|
Vormfelde SV, Burckhardt G, Zirk A, Wojnowski L, Brockmöller J. Pharmacogenomics of diuretic drugs: data on rare monogenic disorders and on polymorphisms and requirements for further research. Pharmacogenomics 2003; 4:701-34. [PMID: 14596636 DOI: 10.1517/phgs.4.6.701.22817] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
This review summarizes the current status of our knowledge about the role of pharmacogenetic variation in response to diuretics and suggests future research topics for the field. Genes with a role in the pharmacokinetics of most diuretics are renal drug transporters, especially OAT1, OAT3 and OCT2 (genes SLC22A6, SLC22A8 and SLC22A2) whereas variants in carbonic anhydrase (CA), cytochrome P450 enzymes and sulfotransferases are relevant only for specific substances. Genes on the pharmacodynamic side include the primary targets of thiazide, loop, K+-sparing and aldosterone antagonistic diuretics: NCC, NKCC2, ENaC and the mineralocorticoid receptor (genes SLC12A3, SLC12A1, SCNN1A, B, G and NR3C2). Rare variants of these proteins cause Gitelman’s syndrome, Bartter’s syndrome, Liddle’s syndrome or pregnancy-induced hypertension. Polymorphisms in these and in associated proteins such as GNB3, α-adducin and angiotensin-converting enzyme (ACE) seem to be clinically relevant. In conclusion, first knowledge has evolved that efficacy of diuretic drugs may be determined by genetic polymorphisms in genes determining pharmacokinetics and pharmacodynamics of this drug class. In the future, the selection of a diuretic drug or the dosing schedules may be individually chosen based on pharmacogenetic parameters, however, many questions remain to be answered before this fantasy becomes reality.
Collapse
Affiliation(s)
- Stefan Viktor Vormfelde
- Department of Clinical Pharmacology & Department of Vegetative Physiology, Georg August University Göttingen, Robert-Koch-Str. 40, D-37075 Göttingen, Germany.
| | | | | | | | | |
Collapse
|
23
|
Abstract
The epithelial sodium channel (ENaC) is a membrane protein made of three different but homologous subunits (a, b, and g) present in the apical membrane of epithelial cells of, for example, the distal nephron. This channel is responsible for salt reabsorption in the kidney and can cause human diseases by increasing channel function in Liddle's syndrome, a form of hereditary hypertension, or by decreasing channel function in pseudohypoaldosteronism type I, a salt-wasting disease in infancy. This review briefly discusses recent advances in understanding the implication of ENaC in Liddle's syndrome and in pseudohypoaldosteronism type I, both caused by mutations in the SCNN1 (ENaC) genes. Furthermore, it is still an open question to which extent SCNN1 genes coding for ENaC might be implicated in essential hypertension. The development of Scnn1 genetically engineered mouse models will provide the opportunity to test the effect of environmental factors, like salt intake, on the development of this kind of salt- sensitive hypertension.
Collapse
Affiliation(s)
- Edith Hummler
- Institut de Pharmacologie et de Toxicologie, Université de Lausanne, Rue du Bugnon 27, CH-1005 Lausanne, Switzerland.
| |
Collapse
|
24
|
Dong YB, Plange-Rhule J, Owusu I, Micah F, Eastwood JB, Carter ND, Saggar-Malik AK, Cappuccio FP, Jeffery S. T594M mutation of the beta-subunit of the epithelial sodium channel in Ghanaian populations from Kumasi and London and a possible association with hypertension. GENETIC TESTING 2002; 6:63-5. [PMID: 12180079 DOI: 10.1089/109065702760093942] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We have tested 186 individuals from Ghana, 95 indigenous and 91 who have settled in the United Kingdom, for the presence of the T594M mutation in the beta-subunit of the epithelial sodium channel, which is associated with hypertension in black populations. The group living in Ghana had a mean age of 27 years and were normotensive, but had an increased frequency of the T allele compared to the London-based population. If this is reflected in larger studies, and the link with hypertension is maintained in the Ghanaian population, this mutation could be a significant cause of hypertension in Ghana.
Collapse
Affiliation(s)
- Y B Dong
- Medical Genetics Unit, St. George's Medical School, Cranmer Terrace, Tooting, London, SW17ORE, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Baker EH, Duggal A, Dong Y, Ireson NJ, Wood M, Markandu ND, MacGregor GA. Amiloride, a specific drug for hypertension in black people with T594M variant? Hypertension 2002; 40:13-7. [PMID: 12105131 DOI: 10.1161/01.hyp.0000022570.02119.75] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The T594M polymorphism of the epithelial sodium channel is found in approximately 5% of people of African origin and is significantly associated with high blood pressure. Although the T594M polymorphism could increase renal sodium absorption through affected channels, it is not known whether this polymorphism causes hypertension. Amiloride specifically inhibits overactive sodium channels and effectively controls blood pressure in Liddle's syndrome, in which hypertension is caused by separate epithelial sodium channel mutations. The aim of this study was to determine whether amiloride was effective in lowering blood pressure in individuals with the T594M polymorphism. In an open, controlled study, 14 black hypertensive individuals with the T594M polymorphism were withdrawn from their usual medication and treated with amiloride. On entry to the study, individuals taking a mean of 2 drugs had blood pressure of 142/89+/-3/3 mm Hg. Amiloride alone (10 mg BID) controlled blood pressure effectively to the same level (140/91+/-4/2 mm Hg). When amiloride was withdrawn for 2 weeks, there was a large increase in blood pressure of 17/8+/-4/2 mm Hg (systolic, P<0.05; diastolic, P<0.01). On restarting amiloride, blood pressure was again controlled to 140/88+/-6/2 mm Hg. These results demonstrate that 10 mg BID amiloride is effective in controlling blood pressure in hypertensive individuals of African origin who have the T594M polymorphism. Our study supports the concept that the T594M polymorphism contributes to the elevation of blood pressure and suggests that consideration should be given to the use of amiloride in affected individuals.
Collapse
Affiliation(s)
- Emma H Baker
- Department of Physiological Medicine, St George's Hospital Medical School, Cranmer Terrace, London, United Kingdom.
| | | | | | | | | | | | | |
Collapse
|