RNA sequencing reveals induction of specific renal inflammatory pathways in a rat model of malignant hypertension.

In malignant hypertension, far more severe kidney injury occurs than in the "benign" form of the disease. The role of high blood pressure and the renin-angiotensin-aldosterone system is well recognized, but the pathogenesis of the renal injury of malignant hypertension (MH) remains incompletely understood. Using the rat model of two-kidney, one-clip renovascular hypertension in which some but not all animals develop MH, we performed a transcriptomic analysis of gene expression by RNA sequencing to identify transcriptional changes in the kidney cortex specific for MH. Differential gene expression was assessed in three groups: MH, non-malignant hypertension (NMH), and normotensive, sham-operated controls. To distinguish MH from NMH, we considered two factors: weight loss and typical renovascular lesions. Mean blood pressure measured intraarterially was elevated in MH (220 ± 6.5 mmHg) as well as in NMH (192 ± 6.4 mmHg), compared to controls (119 ± 1.7 mmHg, p < 0.05). Eight hundred eighty-six genes were exclusively regulated in MH only. Principal component analysis revealed a separated clustering of the three groups. The data pointed to an upregulation of many inflammatory mechanisms in MH including pathways which previously attracted relatively little attention in the setting of hypertensive kidney injury: Transcripts from all three complement activation pathways were upregulated in MH compared to NMH but not in NMH compared with controls; immunohistochemistry confirmed complement deposition in MH exclusively. The expression of chemokines attracting neutrophil granulocytes (CXCL6) and infiltration of myeloperoxidase-positive cells were increased only in MH rats. The data suggest that these pathways, especially complement deposition, may contribute to kidney injury under MH. KEY MESSAGES: The most severe hypertension-induced kidney injury occurs in malignant hypertension. In a rat model of malignant hypertension, we assessed transcriptional responses in the kidney exposed to high blood pressure. A broad stimulation of inflammatory mechanisms was observed, but a few specific pathways were activated only in the malignant form of the disease, notably activation of the complement cascades. Complement inhibitors may alleviate the thrombotic microangiopathy of malignant hypertension even in the absence of primary complement abnormalities.

Thrombotic microangiopathy in aHUS and beyond: clinical clues from complement genetics.

Studies of complement genetics have changed the landscape of thrombotic microangiopathies (TMAs), particularly atypical haemolytic uraemic syndrome (aHUS). Knowledge of complement genetics paved the way for the design of the first specific treatment for aHUS, eculizumab, and is increasingly being used to aid decisions regarding discontinuation of anti-complement treatment in this setting. Complement genetic studies have also been used to investigate the pathogenic mechanisms that underlie other forms of HUS and provided evidence that contributed to the reclassification of pregnancy- and postpartum-associated HUS within the spectrum of complement-mediated aHUS. By contrast, complement genetics has not provided definite evidence of a link between constitutional complement dysregulation and secondary forms of HUS. Therefore, the available data do not support systematic testing of complement genes in patients with typical HUS or secondary HUS. The potential relevance of complement genetics for distinguishing the underlying mechanisms of malignant hypertension-associated TMA should be assessed with caution owing to the overlap between aHUS and other causes of malignant hypertension. In all cases, the interpretation of complement genetics results remains complex, as even complement-mediated aHUS is not a classical monogenic disease. Such interpretation requires the input of trained geneticists and experts who have a comprehensive view of complement biology.

Severe and malignant hypertension are common in primary atypical hemolytic uremic syndrome.

Malignant hypertension is listed among the causes of secondary thrombotic microangiopathy, but pathogenic mutations in complement genes have been reported in patients with hypertension-induced thrombotic microangiopathy. Here we investigated the frequency and severity of hypertension in 55 patients with primary atypical hemolytic uremic syndrome (aHUS). A genetic analysis was performed in all patients, and funduscopic examination was performed in all the patients with Grades 2 and 3 hypertension. A cohort of 110 patients with malignant hypertension caused by diseases other than aHUS served as control. Thirty-six patients with aHUS presented Grade 2 or Grade 3 hypertension and funduscopic examination showed malignant hypertension in 19. Genetic abnormalities in complement were found in 19 patients (37% among patients with malignant hypertension). Plasmapheresis was performed in 46 patients and 26 received eculizumab. Renal and hematological responses were significantly lower after plasmapheresis (24%) than after eculizumab (81%). Renal survival was significantly higher in patients treated with eculizumab (85% at one, three and five years) compared to patients who did not receive this treatment (54%, 46% and 41%), respectively. Response to eculizumab was independent of hypertension severity and the presence of complement genetic abnormalities. Among patients with malignant hypertension caused by other diseases the prevalence of thrombotic microangiopathy was very low (5%). Thus, severe and malignant hypertension are common among patients with aHUS and eculizumab treatment leads to a higher renal survival when compared to plasmapheresis. However, thrombotic microangiopathy is uncommon among patients presenting with malignant hypertension caused by diseases other than aHUS.

Thrombomodulin and Endothelial Dysfunction: A Disease-Modifier Shared between Malignant Hypertension and Atypical Hemolytic Uremic Syndrome.

Thrombomodulin (TM) is an endothelial glycoprotein that is present in all blood vessels. Five percent of all patients with atypical hemolytic uremic syndrome (aHUS) have mutations in the gene coding for TM, with a peak presentation in young children. Mutations often translate into quantitative and qualitative abnormalities of this endothelial glycoprotein. Outcome of the TM-associated aHUS is relatively poor with frequent relapses after transplantation despite its membrane-bound character. We observed a woman presenting with malignant hypertension (MHT) and associated kidney, brain, cardiac, and hematological involvement with thrombotic microangiopathy on kidney biopsy. She had a documented mutation of the gene coding for TM, which was associated with both aHUS and an increased risk for venous and arterial thrombosis. As TM has anti-coagulant, anti-inflammatory, and cytoprotective properties and also attenuates alternative complement activation, this glycoprotein could play an active role in other diseases with endothelial involvement apart from aHUS. We discuss the potential role of TM in the pathophysiology of various endotheliopathies including MHT. We also provide a framework for future therapeutic options.

[Pharmacogenetics in anesthesia and intensive care medicine : Clinical and legal challenges exemplified by malignant hyperthermia]. / Pharmakogenetik in Anästhesie und Intensivmedizin : Klinische und juristische Herausforderung am Beispiel der Malignen Hyperthermie.

Pharmacotherapy is a key component of anesthesiology and intensive care medicine. The individual genetic profile influences not only the effect of pharmaceuticals but can also completely alter the mode of action. New technologies for genetic screening (e.g. next generation sequencing) and increasing knowledge of molecular pathways foster the disclosure of pharmacogenetic syndromes, which are classified as rare diseases. Taking into account the high genetic variability in humans and over 8000 known rare diseases, up to 20 % of the population may be affected. In summary, rare diseases are not rare. Most pharmacogenetic syndromes lead to a weakening or loss of pharmacological action. In contrast, malignant hyperthermia (MH), which is the most relevant pharmacogenetic syndrome for anesthesia, is characterized by a pharmacologically induced overactivation of calcium metabolism in skeletal muscle. Volatile anesthetic agents and succinylcholine trigger life-threatening hypermetabolic crises. Emergency treatment is based on inhibition of the calcium release channel of the sarcoplasmic reticulum by dantrolene. After an adverse pharmacological event patients must be informed and a clarification consultation must be carried out during which the hereditory character of MH is explained. The patient should be referred to a specialist MH center where a predisposition can be diagnosed by the functional in vitro contracture test from a muscle biopsy. Additional molecular genetic investigations can yield mutations in the genes for calcium-regulating proteins in skeletal muscle, e.g. ryanodine receptor 1 (RyR1) and calcium voltage-gated channel subunit alpha 1S (CACNA1S). Currently, an association to MH has only been shown for 35 mutations out of more than 400 known and probably hundreds of unknown genetic variations. Furthermore, MH predisposition is not excluded by negative mutation screening. For anesthesiological patient safety it is crucial to identify individuals at risk and warn genetic relatives; however, the legal requirements of the Patients Rights Act and the Human Genetic Examination Act must be strictly adhered to. Specific features of insurance and employment law must be respected under consideration of the Human Genetic Examination Act.

Impact of a novel mutation in the 5'-flanking region of natriuretic peptide precursor B gene on the antihypertensive effects of sodium nitroprusside in patients with hypertension.

Our aim was to identify the possible mutations of the natriuretic peptide precursor B (NPPB) gene in a family with hereditary hypertension, and determine whether the mutations are associated with the antihypertensive effect of sodium nitroprusside. The subjects included one family with hereditary hypertension, 36 cases of sporadic hypertension and 120 healthy controls. The 5'-flanking sequence of NPPB was amplified with PCR, and the presence of mutations was analyzed by direct sequencing. Patients with hypertension were treated with sodium nitroprusside and blood pressure data and serum B-type natriuretic peptide (BNP) levels were measured. A novel complex mutation in 5'-flanking sequence of the NPPB gene was detected in three patients (II 2, III 2, and III 5) of the hypertension family, which included c.-1195_ -1176 insert 5'-CCTTCTTTCTTTCTTTCTTT-3', c.-1208 T>A, c.-1214 T>C, and c.-1216 T>A. Patients with this mutation were less sensitive to sodium nitroprusside treatment. Sporadic hypertension patients (without NPPB gene mutation) and patients with the c.-1181 T>A point mutation were sensitive to sodium nitroprusside treatment. BNP levels of patients with the complex mutation were significantly lower than that of sporadic hypertension patients and c.-1181 T>A mutation patients before and during the early stage of sodium nitroprusside treatment. The complex mutation of the NPPB gene might be an etiological factor of hereditary malignant hypertension, and it is associated with low sensitivity to the antihypertensive effect of sodium nitroprusside.

Transient induction of ANG II-dependent malignant hypertension causes sustained elevation of blood pressure and augmentation of the pressor response to ANG II in CYP1A1-REN2 transgenic rats.

INTRODUCTION: Transgenic rats with inducible expression of the mouse Ren2 renin gene [strain name: TGR(Cyp1a1Ren2)] allow induction of various degrees of ANG II-dependent hypertension. Dietary administration of the aryl hydrocarbon indole-3-carbinol (I3C) at a dose of 0.15% induces a slowly developing form of ANG II-dependent hypertension, whereas dietary administration of a higher dose (0.3%) of I3C results in the development of ANG II-dependent malignant hypertension. Cessation of administration of 0.15% I3C results in the normalization of blood pressure, indicating the reversibility of hypertension induced by this dose of I3C. The present study was performed to determine if ANG II-dependent malignant hypertension is similarly reversible following cessation of dietary administration of 0.3% I3C. METHODS: Cyp1a1-Ren2 rats (n = 6) were fed a normal diet containing 0.3% I3C for 11 days to induce malignant hypertension. RESULTS: Cyp1a1-Ren2 rats induced with I3C exhibited pronounced increases in systolic blood pressure (SBP) (132 +/- 3-229 +/- 11 mm Hg, P < 0.001) and marked decreases in body weight (303 +/- 4-222 +/- 2 g, P < 0.001). When I3C administration was terminated, SBP decreased to 167 +/- 4 mm Hg (P < 0.01) and body weight increased to normal levels (309 +/- 2 g, P < 0.01) within 12 days. However, SBP remained significantly elevated (172 +/- 1 mm Hg, P < 0.01) for up to 3 weeks after termination of dietary administration of 0.3% I3C. In addition, the magnitude of the blood pressure response to intravenous bolus administration of 50 ng of ANG II (50 microL in volume) 3 weeks after cessation of dietary I3C administration was substantially higher than that observed in normotensive control rats (134 +/- 1 mm Hg, n = 6) not previously induced with 0.3% I3C (53 +/- 2 versus 38 +/- 3 mm Hg, P < 0.05). CONCLUSIONS: The present findings demonstrate that transient induction of ANG II-dependent malignant hypertension results in prolonged elevations of arterial blood pressure and marked augmentation of the magnitude of the pressor response to ANG II in Cyp1a1-Ren2 transgenic rats.

Common genetic variants in the chromogranin a promoter are associated with renal injury in IgA nephropathy patients with malignant hypertension.

The present study aimed to investigate whether genetic variants in the chromogranin A (CHGA) promoter were associated with malignant hypertension (MHT) and renal functional damage. The polymorphisms of CHGA promoter in 39 patients with malignant hypertension secondary to idiopathic IgA nephropathy (IgAN-MHT), 23 patients with primary malignant hypertension and 63 controls were genotyped by sequencing. Four diploid genotypes with minor allele frequencies of approximately >or=10% for individual CHGA SNP loci or haplotypes were compared among the patient with IgAN-MHT, primary MHT and healthy control. Polymorphisms and haplotypes of CHGA promoter were not associated with primary MHT and IgAN-MHT. Within 39 IgAN-MHT patients whose clinical and histological data were available, patients carrying -415TT genotype tended to present with higher serum creatinine (Scr) level than those carrying -415TC/CC genotype (636.94 +/- 524.07 micromol/L vs 277.84 +/- 196.39 micromol/L, P = 0.014). Consistent with this statistic, we found the haplotype-specific score value of haplotype ATC was 2.25046 (p = 0.024), and by permutation testing, the empirical p value was 0.014. The present study suggested the genetic variants in the chromogranin A promoter may not involve in the onset of malignant hypertension, but the variants might play a role in the renal dysfunction in patients with IgAN-MHT.

Increased sympathetic activity in normotensive offspring of malignant hypertensive parents compared to offspring of normotensive parents.

Malignant hypertension seems to be the consequence of very high blood pressure. Furthermore, an increase in sympathetic and renin-angiotensin system activity is considered to be the main mechanisms producing malignant hypertension. In the present study, 10 offspring of malignant hypertensive (OMH) parents (age 28 +/- 5 years, 7 males, 3 females, 2 white and 8 non-white) and 10 offspring of normotensive (ONT) parents (age 28 +/- 6 years, 2 males, 8 females, 3 white and 7 non-white) were evaluated. The OMH group had significantly higher (P < 0.05) casual blood pressure (125 +/- 10/81 +/- 5 mmHg) compared with ONT (99 +/- 13/67 +/- 5 mmHg). The increase in blood pressure was greater in OMH (Delta SBP = 17 +/- 2 vs Delta SBP = 9 +/- 1 mmHg in ONT) during cold pressor testing, but they had a lower increase in heart rate (Delta HR = 13 +/- 2 vs Delta HR = 20 +/- 3 bpm in ONT) during isometric exercise(handgrip test). Sympathetic activity, measured by microneurography, was significantly higher (P < 0.05) before exercise in OMH (17 +/- 6 vs 11 +/- 4 burst/min in ONT) and exhibited a greater increase (Delta = 18 +/- 10 vs Delta = 8 +/- 3 burst/min in ONT) during isometric exercise. This study showed increased sympathetic activity in OMH before exercise and a greater response during isometric exercise, suggesting an autonomic abnormality before exercise and a greater sympathetic response to physical stress in OMH compared to ONT.

Increased sympathetic activity in normotensive offspring of malignant hypertensive parents compared to offspring of normotensive parents

Malignant hypertension seems to be the consequence of very high blood pressure. Furthermore, an increase in sympathetic and renin-angiotensin system activity is considered to be the main mechanisms producing malignant hypertension. In the present study, 10 offspring of malignant hypertensive (OMH) parents (age 28 ± 5 years, 7 males, 3 females, 2 white and 8 non-white) and 10 offspring of normotensive (ONT) parents (age 28 ± 6 years, 2 males, 8 females, 3 white and 7 non-white) were evaluated. The OMH group had significantly higher (P < 0.05) casual blood pressure (125 ± 10/81 ± 5 mmHg) compared with ONT (99 ± 13/67 ± 5 mmHg). The increase in blood pressure was greater in OMH (Ä SBP = 17 ± 2 vs Ä SBP = 9 ± 1 mmHg in ONT) during cold pressor testing, but they had a lower increase in heart rate (Ä HR = 13 ± 2 vs Ä HR = 20 ± 3 bpm in ONT) during isometric exercise (handgrip test). Sympathetic activity, measured by microneurography, was significantly higher (P < 0.05) before exercise in OMH (17 ± 6 vs 11 ± 4 burst/min in ONT) and exhibited a greater increase (Ä = 18 ± 10 vs Ä = 8 ± 3 burst/min in ONT) during isometric exercise. This study showed increased sympathetic activity in OMH before exercise and a greater response during isometric exercise, suggesting an autonomic abnormality before exercise and a greater sympathetic response to physical stress in OMH compared to ONT.

Late-onset endothelin receptor blockade in hypertensive heterozygous REN-2 transgenic rats.

Our previous studies in heterozygous Ren-2 transgenic rats (TGR) have shown that early treatment with selective endothelin (ET)(A) receptor blockade is superior to nonselective ET(A/B) receptor blockade. The aim of this study was to evaluate the role of the ET system in male heterozygous TGR with established hypertension (late-onset treatment). TGR and control Hannover Sprague-Dawley (HanSD) rats were fed a high-salt diet and were treated concomitantly with the nonselective ET(A/B) receptor blocker bosentan or the selective ET(A) receptor blocker atrasentan from day 52 of age on. Survival rate was partly increased by bosentan and fully normalized with atrasentan. Bosentan transiently decreased blood pressure (BP), whereas atrasentan significantly reduced BP as early as one week after the start of the treatment. This effect persisted for the whole experimental period. Atrasentan also substantially reduced cardiac hypertrophy, proteinuria, glomerulosclerosis and left ventricle ET-1 content. Bosentan improved and atrasentan almost restored podocyte architecture and reversed changes in podocyte phenotype represented by the expression of CD 10, desmin and vimentin. Our results demonstrate that selective ET(A) receptor blockade has more favorable effects than nonselective ET(A/B) receptor blockade and, unlike observed in homozygous TGR, ET(A) receptor blockade has similar effects in heterozygous rats with established hypertension as in young animals with developing hypertension.

The M235T polymorphism in the angiotensinogen gene is associated with the risk of malignant hypertension in white patients.

BACKGROUND: Malignant hypertension can be considered an extreme phenotype of renin-mediated hypertension. Therefore, we compared the allelic frequencies of the angiotensinogen (AGT) M235T, angiotensin-converting enzyme insertion/deletion (ACE I/D) and angiotensin II-type I receptor (AT1R) A1166C polymorphisms in malignant hypertensive patients with hypertensive and normotensive controls. METHODS: A total of 101 consecutive patients between 1995 and 2005 admitted to a large university hospital fulfilled the criteria for malignant hypertension. Seventy-five patients (74%) were compared with 150 hypertensive and 150 normotensive controls, randomly selected from a population study and individually matched on age, sex and ethnicity. RESULTS: The odds of malignant hypertension in white subjects with the TT genotype of the AGT M235T polymorphism was 14.3 (5.5-37) compared to hypertensive controls, and 9.4 (3.8-23.2) compared to normotensive controls. Adjustment for age, sex, smoking and antihypertensive therapy did not affect this association. The association of AGT M235T with malignant hypertension was not significant in blacks. In patients with malignant hypertension, the TT genotype was associated with more severe renal dysfunction and microangiopathic haemolysis. No differences were found in allele frequencies of the ACE I/D or the AT1R A1166C polymorphisms between study groups. CONCLUSIONS: The TT genotype of AGT M235T is associated with malignant hypertension in whites, carriers having an odds of approximately 10 to 1 compared to hypertensive and normotensive controls. These observations may provide a better understanding of the pathophysiology of malignant hypertension and offer possibilities for identifying patients at risk. Larger association or linkage studies are needed for a more detailed risk assessment.

Long-term administration of rho-kinase inhibitor ameliorates renal damage in malignant hypertensive rats.

We have shown recently that fasudil, a Rho-kinase inhibitor, has renoprotective effects in salt-sensitive hypertensive rats. We hypothesized that activation of Rho-kinase is involved in the pathogenesis of glomerulosclerosis in malignant hypertensive rats. To test this hypothesis, we studied the following 4 groups: control Wistar-Kyoto rats, untreated deoxycorticosterone-acetate salt spontaneously hypertensive rats (DOCA-SHR), low-dose fasudil-treated DOCA-SHR, and high-dose fasudil-treated DOCA-SHR. After 3 weeks of treatment, the effects of fasudil were examined. DOCA-SHR was characterized by increased blood pressure (BP); increased kidney weight; decreased renal function; increased proteinuria; abnormal histological findings; increased monocyte/macrophage infiltration; increased urinary 8-isoprostran levels; increased gene expression of collagen I, collagen III, transforming growth factor-beta, and reduced nicotinamide-adenine dinucleotide phosphate oxidase subunits (p40phox, p47phox, and p67phox); and decreased gene expression of endothelial NO synthase (eNOS) in the renal cortex as compared with Wistar-Kyoto rats. Long-term high-dose fasudil treatment significantly improved renal function and histological findings without changing BP, as compared with untreated DOCA-SHR. Interestingly, long-term fasudil treatment significantly decreased monocyte/macrophage infiltration and urinary 8-isoprostran excretion, in association with decreased mRNA levels of transforming growth factor-beta, collagen I, collagen III, and NADPH oxidase subunits (p40phox, p47phox, and p67phox), and increased mRNA levels of eNOS in the renal cortex. Long-term low-dose fasudil treatment tended to improve these variables slightly but did not affect most of them significantly. Our results suggest that long-term fasudil treatment provides renoprotective effects independent of BP-lowering activity. These renoprotective effects are associated with inhibition of extracellular matrix gene expression, monocyte/macrophage infiltration, oxidative stress, and upregulation of eNOS gene expression.

Angiotensin-converting enzyme i/d polymorphism in patients with malignant hypertension.

The angiotensin-converting enzyme (ACE) gene has been implicated in the manifestation of the phenotype of malignant hypertension (MH). In 1990 the ACE gene polymorphism characterized by the insertion or deletion of a 287-base pair fragment in the 17q23 chromosome was identified. The DD genotype is associated with increased tissue and circulating ACE levels and elevated angiotensin II. ACE polymorphism was studied in 48 patients with MH, 25 patients with non-MH, and a control group of 78 normotensive individuals by real-time polymerase chain reaction using the LightCycler system (Roche Diagnostics Corporation, Indianapolis, IN). The DD genotype was found statistically more frequently in MH patients than controls (p=0.028; odds ratio, 2.5; confidence interval, 1.1-5.5). Presence of the DD genotype of the ACE gene is more frequent in MH patients than in controls, indicating that this genotype could be a significant risk factor and a predictor for the development of MH.

Association of the D allele of the angiotensin I converting enzyme polymorphism with malignant vascular injury.

AIMS: To determine whether there is an association between the insertion/deletion (I/D) polymorphism of the human angiotensin I converting enzyme (ACE) gene and malignant vascular injury (MVI). METHODS: The polymerase chain reaction was used to genotype DNA extracted from archival, paraffin wax embedded renal biopsy material from 48 patients with MVI, made up from cases of malignant hypertension (n = 23), scleroderma (n = 10), and haemolytic uraemic syndrome (n = 15), and from whole blood samples from 191 healthy controls. RESULTS: The D allele was found more frequently in cases of MVI than in healthy controls, (65% v 52%). Both the DD and I/D genotypes occurred significantly more frequently in patients with MVI than did the II genotype (chi(2) = 7.26, p = 0.007; and chi(2) = 4.06, p = 0.04, respectively). CONCLUSIONS: Possession of at least one copy of the D allele is associated with an increased risk of developing MVI. Our data support a dominant mode of effect for the D allele. Use of the I/D polymorphism as a genetic marker for MVI may be of value clinically in identifying at risk individuals before the development of target end organ damage. Furthermore, those at risk may benefit from early ACE inhibition.

Malignant hypertension - the role of the paracrine renin-angiotensin system.

Malignant hypertension remains one of the life-threatening complications of blood pressure elevation. It is a clinico-pathological syndrome of severe blood pressure elevation combined with malignant vascular injury. This is a characteristic form of vascular damage, with two elements: fibrinoid necrosis and endarteritis proliferans. Although the morphology of these has been well described, the molecular events are not fully understood. This review summarizes the evidence from transgenic animals for a role for the activation of a local paracrine renin-angiotensin system in the pathogenesis of malignant vascular injury. These animal models provide pathological, pharmacological, and genetic evidence supporting the hypothesis that intra-renal generation of angiotensin 2 and exposure of the microcirculation to elevated blood pressure co-operate in causing tissue damage in malignant hypertension.

G-protein beta3 subunit gene (GNB3) polymorphism 825C-->T in patients with hypertensive crisis.

OBJECTIVE: The polymorphism 825C-->T in exon 10 of the gene GNB3 encoding the beta3 subunit of heterotrimeric guanine nucleotide binding regulatory proteins (G-proteins) results in a splicing variant (GNB3-s) in which the nucleotides 498-620 of exon 9 are deleted. The T allele has been shown to be overrepresented in patients with essential hypertension. Because GNB3-s may support the development of severe elevation of blood pressure, we hypothesized that GNB3 825C-->T may be present more frequently in patients with hypertensive crisis. DESIGN: Case control study. SETTING: Department of Emergency Medicine at the University Hospital of Vienna, Vienna, Austria. PATIENTS: A total of 174 patients admitted to an emergency department for treatment of hypertensive crisis diagnosed as suffering from essential hypertension. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patients were genotyped for the 825C-->T transition in GNB3. An equal number of age- and gender-matched normotensive, healthy individuals served as the control population. The allele frequency of 825C-->T in the GNB3 gene was 0.310 in patients with hypertensive crisis and 0.342 in the control group. There was no difference in genotype distribution and allele frequency between the patients and the age- and gender-matched control group or between the observed prevalence and the occurrence rate expected from the Hardy-Weinberg principle within each group. CONCLUSIONS: GNB3 825C-->T is not associated with the phenotype of hypertensive crisis in patients suffering from essential hypertension. Furthermore, our data do not support the concept that the 825C-->T transition in the GNB3 gene is associated with essential hypertension.