Search

Item does not contain fulltext Liddle syndrome is an autosomal dominant form of hypokalemic hypertension due to mutations in the beta- or gamma-subunit of the epithelial sodium channel (ENaC). Here, we describe a family with Liddle syndrome due to a mutation in alphaENaC. The proband was referred because of resistant hypokalemic hypertension, suppressed renin and aldosterone, and no mutations in the genes encoding beta- or gammaENaC. Exome sequencing revealed a heterozygous, nonconservative T>C single-nucleotide mutation in alphaENaC that substituted Cys479 with Arg (C479R). C479 is a highly conserved residue in the extracellular domain of ENaC and likely involved in a disulfide bridge with the partner cysteine C394. In oocytes, the C479R and C394S mutations resulted in similar twofold increases in amiloride-sensitive ENaC current. Quantification of mature cleaved alphaENaC in membrane fractions showed that the number of channels did not increase with these mutations. Trypsin, which increases open probability of the channel by proteolytic cleavage, resulted in significantly higher currents in the wild type than in C479R or C394S mutants. In summary, a mutation in the extracellular domain of alphaENaC causes Liddle syndrome by increasing intrinsic channel activity. This mechanism differs from that of the beta- and gamma-mutations, which result in an increase in channel density at the cell surface. This mutation may explain other cases of patients with resistant hypertension and also provides novel insight into ENaC activation, which is relevant for kidney sodium reabsorption and salt-sensitive hypertension.

Introduction Diospyros rhodocalyx (Tako-Na) is a Thai folk medicine purported to promote longevity, treat impotence, etc. We present patients with hypokalemia, weakness and hypertension after consuming Tako-Na tea. Case series Case 1: A 61-year-old man was brought in nine hours after drinking 400-500 mL of Tako-Na tea. One handful of Tako-Na bark was boiled in water to make tea. He had vomiting and watery diarrhea six hours after drinking it. He took no medications and had no history of hypertension. The only remarkable vital sign was BP 167/90 mmHg. Physical examination revealed generalized muscle weakness. Laboratory findings were potassium 2.7 mmol/L, bicarbonate 24 mmol/L, and transtubular potassium gradient (TTKG) 5.6. He was discharged the next day with a BP 140/90 mmHg and potassium 4.2 mmol/L. Case 2: A 78-year-old man, a friend of case 1, also drank Tako-Na tea from the same pot at the same time as case 1. He also had vomiting and diarrhea six hours later. He took no medications despite past history of hypertension (baseline SBP 140-160). Initial BP was 230/70 mmHg. He also had muscle weakness. Laboratory findings were potassium 3.3 mmol/L, bicarbonate 24 mmol/L, TTKG 7.37 and normal thyroid function. He was also discharged the next day with a BP 148/70 mmHg and potassium 4.2 mmol/L. Case 3-7: These were patients reported to a poison center and their potassium concentrations were 1.4, 1.4, 3.3, 1.3 and 1.2 mmol/L, respectively. Three of them were intubated and case 3 died. Conclusions Tako-Na contains betulin, betulinic acid, taraxerone, lupeol, and lupenone. Their structures are similar to glycyrrhetic acid, the active metabolite of glycyrrhizic acid found in licorice which is well known to cause pseudoaldosteronism. Glycyrrhetic acid is potent in inhibiting 11-beta-hydroxysteroid dehydrogenase, and causes pseudoaldosteronism. We hypothesize that the compounds in Tako-Na act in the same way as glycyrrhetic acid in producing pseudoaldosteronism.

Liddle's syndrome, an autosomal dominant form of monogenic hypertension, is characterized by salt-sensitive hypertension with early penetrance, hypokalemia, metabolic alkalosis, suppression of plasma rennin activity and aldosterone secretion, and a clear-cut response to epithelial sodium channel blockers but not spironolactone therapy. Here, we describe the case of a 16-year-old boy patient with resistant hypertension (maintain 170-180/100-110 mm Hg after administration four kinds of antiypertensive drugs) and severe hypokalemia. After a series of checks, we exclude primary aldosteronism and renal artery stenosis and other diseases. Finally, the Liddle syndrome was diagnosed because of the DNA sequencing found that the proband's mother and himself had mutations P616L (c.1847 C>T) in the SCNN1B gene. Liddle syndrome should be considered as a cause of hypertension in children or adolescents particularly with suppressed renin activity. Early diagnosis and appropriately tailored treatment avoid complications of long-term unrecognized or inappropriately managed hypertension. Genetic testing has made it possible to make accurate diagnoses and develop tailored therapies for mutation carriers. The role of genetic testing and genetic counseling in establishing the early diagnosis of Liddle's syndrome is important.

Background Posaconazole-induced pseudohyperaldosteronism (PIPH) has been associated with elevated posaconazole serum concentrations. Clinicians are faced with the difficult task of managing patients with PIPH while not compromising the efficacy of antifungal prophylaxis or treatment. Commonly, modifications to posaconazole therapy are utilized in managing PIPH including dosage reduction of posaconazole or therapeutic switch to an alternative antifungal. Methods We retrospectively reviewed 20 consecutive adult patients diagnosed with PIPH in this case series. Patient data including blood pressure, electrolytes, endocrine laboratory values, and posaconazole serum concentrations collected before and after therapeutic intervention. Results Out of 20 patients included, 17 patients (85%) underwent therapeutic modification with posaconazole dose reduction (N=11) as the most common change. Other modifications included posaconazole discontinuation (N=3), switch to an alternative antifungal (N=2), and addition of spironolactone (N=1). Clinical improvement (a decrease in systolic blood pressure and increase in serum potassium) was observed in 9 of 17 patients (52.9%). Table 1. Management of Posaconazole-Induced Pseudohyperaldosteronism - p1 Table 1. Management of Posaconazole-Induced Pseudohyperaldosteronism - p2 Table 1. Management of Posaconazole-Induced Pseudohyperaldosteronism - p3 Conclusion We report our experience with PIPH management, for which there is currently no universally effective strategy. We suggest a stepwise approach for PIPH management, starting with posaconazole dose reduction and repeat assessment of clinical and laboratory parameters. If resolution of PIPH is not achieved, an alternative triazole antifungal or the addition of an aldosterone antagonist are additional potential interventions. Even with this approach, it is possible for PIPH to persist after therapeutic modification. Thus, early diagnosis and continuous, close monitoring of patients is warranted. Disclosures All Authors: No reported disclosures

Hypokalemia refers to a deficiency of potassium in the bloodstream with or without clinical signs and symptoms. It is a common electrolyte disbalance found in all age groups. There are many causes of hypokalemia and though rare but certain renal tubular channelopathies as Gitelman syndrome (GS), Bartter syndrome, and Liddle syndrome can also be manifest with altered arterial blood gas, blood pressure, and hypokalemia. In the presented case, a 37-year-old man with generalized weakness, muscle cramps, and hypotension was found to have hypokalemia. Ruling out the possible common causes of hypokalemia with hypotension and alkalotic pH and his resistance to potassium replacement was investigated for renal tubular channelopathies. He was found to have blood and urinary parameters favoring GS. He showed marked improvement in his symptoms on Aldactone. This has opened our minds to try to see for these channelopathies as potential causes of hypokalemia and improvement of the same on addressing the defect.

Resistant hypertension is a common clinical entity, defined as suboptimal blood pressure response to multiple therapies after excluding medication nonadherence and secondary forms of hypertension. Patients with resistant hypertension generally share several comorbidities. Resistant hypertension is more common in individuals of African descent. Blood pressure should be optimized using multiple strategies, including lifestyle changes and single-pill combination therapies, with the aim of reducing cardiovascular events while reducing side effects from using antihypertensive therapy. A renin/aldosterone-based diagnostic and treatment approach will help tailor therapy. The use of mineralocorticoid receptor antagonists or amiloride as appropriate is favored.

Pseudohyperaldosteronism, or Liddle syndrome, is a rare, autosomal dominant condition characterized by early-onset hypertension, often associated with hypokalemia and metabolic alkalosis. Martorell hypertensive ischemic leg ulcer is a rare, underdiagnosed ulcer characterized by subcutaneous arteriolosclerosis, classically appearing over the dorsolateral lower extremity or Achilles tendon in patients with hypertension and diabetes. It presents an important diagnostic challenge because it can appear grossly similar to other entities such as pyoderma gangrenosum or venous stasis ulcers, but requires surgical intervention. This article presents a case study of surgical management of a Martorell ulcer in a 69-year-old woman with Liddle syndrome. To the authors' knowledge, this is the first case reported in the literature of this rare ulcer occurring secondary to this rare cause of hypertension.

Hypertension is a significant public health problem. Thirty percent of cases are caused by a single genetic mutation. Hypertension is the predominant and usually the only manifestation in monogenic hypertension Monogenic hypertension may involve mineralcorticoid-dependent or -independent increase in Na+ transport. Diagnosis is based on routine physical examination, blood pressure measurement and laboratory analysis of renin, aldosterone, cortisol and potassium. Genetic testing is useful for confirming diagnosis and for differential diagnosis. Monogenic hypertension has autosomal dominant or autosomal recessive inheritance. (www.actabiomedica.it)

Background/Aims: Liddle syndrome (LS) is a rare autosomal dominant disease caused by mutations in genes coding for epithelial sodium channel (ENaC) subunits. The aim of this study was to identify the mutation responsible for the LS in an extended Chinese family. Methods: DNA samples from the proband with early-onset, treatment-resistant hypertension, and hypokalemia and 19 additional relatives were all sequenced for mutations in exon 13 of the β-ENaC and γ-ENaC genes, using amplification by polymerase chain reaction and direct DNA sequencing. Results: Genetic testing of exon 13 of SCNN1B revealed duplication of guanine into a string of 3 guanines located at codon 602. This frameshift mutation is predicted to generate a premature stop codon at position 607, resulting in truncated β-ENaC lacking the remaining 34 amino acids, including the crucial PY motif. Among a total of 9 participants with the identical mutation, different phenotypes were identified. Tailored treatment with amiloride was safe and effective in alleviating disease symptoms in LS. No mutation of SCNN1G was identified in any of the examined participants. Conclusions: We report here a family affected by LS harboring a frameshift mutation (c.1806dupG) with a premature stop codon deleting the PY motif of β-ENaC. Our study demonstrates that the earlier LS patients are diagnosed by genetic testing and treated with tailored medication, the greater the likelihood of preventing or minimizing complications in the vasculature and target organs.

Background Liddle syndrome is a monogenic disease with autosomal dominant inheritance. Basic characteristics of this disease are hypertension, reduced concentration of aldosterone and renin activity, as well as increased excretion of potassium leading to low level of potassium in serum and metabolic alkalosis. The cause of Liddle syndrome is missense or frameshift mutations in SCNN1A, SCNN1B, or SCNN1G genes that encode epithelial sodium channel subunits. Case presentation We describe a family with Liddle syndrome from Russia. 15-year-old proband has arterial hypertension, hypokalemia, hyporeninemia, metabolic alkalosis, but aldosterone level is within the normal range. At 12 years of age, arterial hypertension was noticed for the first time. We identified novel frameshift mutation c.1769delG (p.Gly590Alafs) in SCNN1G, which encodes the γ subunit of ENaC in vertebrates. The father and younger sister also harbor this heterozygous deletion. Treatment with amiloride of proband and his sister did not normalize the blood pressure, but normalized level of plasma renin activity. Conclusions Our results expand the mutational spectrum of Liddle syndrome and provide further proof that the conserved PY motif is crucial to control of ENaC activity. Genetic analysis has implications for the management of hypertension, specific treatment with amiloride and counselling in families with Liddle syndrome.

Essential hypertension is a highly prevalent disease in the general population. Secondary hypertension is characterized by a specific and potentially reversible cause of increased blood pressure levels. Some secondary endocrine forms of hypertension are common (caused by uncontrolled cortisol, aldosterone, or catecholamines production). This article describes rare monogenic forms of hypertension, characterized by electrolyte disorders and suppressed renin-aldosterone axis. They represent simple models for the physiology of renal control of sodium levels and plasma volume, thus reaching a high scientific interest. Furthermore, they could explain some features closer to the essential phenotype of hypertension, suggesting a mechanistically driven personalized treatment.

Liddle syndrome (LS) is a familial disease characterized by early onset hypertension (HT). Although regarded as rare, its incidence may be greater than expected because the classical findings of hypokalemic metabolic alkalosis with suppressed renin and aldosterone levels are not consistently present. Herein, we present the case of an adolescent boy and maternal relatives who were followed up with misdiagnosis of essential HT for a long duration. Clinical diagnosis of LS was confirmed on genetic analysis. Despite carrying the same mutation, the index patient and the family members manifested heterogeneous phenotypes of the disease including age at presentation, degree of HT, presence of hypokalemia and renal/cardiac complications. LS should be considered in the differential diagnosis of HT in children with a strong family history of HT resistant to conventional treatment; and genetic screening should be performed in these circumstances.

Pseudohyperaldosteronism is characterized by a clinical picture of hyperaldosteronism with suppression of renin and aldosterone. It can be due to endogenous or exogenous substances that mimic the effector mechanisms of aldosterone, leading not only to alterations of electrolytes and hypertension, but also to an increased inflammatory reaction in several tissues. Enzymatic defects of adrenal steroidogenesis (deficiency of 17α-hydroxylase and 11β-hydroxylase), mutations of mineralocorticoid receptor (MR) and alterations of expression or saturation of 11-hydroxysteroid dehydrogenase type 2 (apparent mineralocorticoid excess syndrome, Cushing's syndrome, excessive intake of licorice, grapefruits or carbenoxolone) are the main causes of pseudohyperaldosteronism. In these cases treatment with dexamethasone and/or MR-blockers is useful not only to normalize blood pressure and electrolytes, but also to prevent the deleterious effects of prolonged over-activation of MR in epithelial and non-epithelial tissues. Genetic alterations of the sodium channel (Liddle's syndrome) or of the sodium-chloride co-transporter (Gordon's syndrome) cause abnormal sodium and water reabsorption in the distal renal tubules and hypertension. Treatment with amiloride and thiazide diuretics can respectively reverse the clinical picture and the renin aldosterone system. Finally, many other more common situations can lead to an acquired pseudohyperaldosteronism, like the expansion of volume due to exaggerated water and/or sodium intake, and the use of drugs, as contraceptives, corticosteroids, β-adrenergic agonists and FANS. In conclusion, syndromes or situations that mimic aldosterone excess are not rare and an accurate personal and pharmacological history is mandatory for a correct diagnosis and avoiding unnecessary tests and mistreatments.

The ENaC/degenerin ion channel superfamily includes the amiloride-sensitive epithelial sodium channel (ENaC) and acid sensitive ionic channel (ASIC). ENaC is a multimeric ion channel formed by heteromultimeric membrane glycoproteins, which participate in a multitude of biological processes by mediating the transport of sodium (Na+) across epithelial tissues such as the kidney, lungs, bladder, and gut. Aberrant ENaC functions contribute to several human disease states including pseudohypoaldosteronism, Liddle syndrome, cystic fibrosis, and salt-sensitive hypertension. Increasing evidence suggests that ion channels not only regulate ion homeostasis and electric signaling in excitable cells but also play important roles in cancer cell behaviors such as proliferation, apoptosis, invasion, and migration. Indeed, ENaCs/ASICs had been reported to be associated with cancer characteristics. Given their cell surface localization and pharmacology, pharmacological strategies to target ENaC/ASIC family members may be promising cancer therapeutics.

Summary Resistant hypertension is a common clinical problem in South Africa and is frequently associated with low renin and aldosterone levels, especially in black Africans. In South Africa, novel variants in the epithelial sodium channel (ENaC) have been described to be associated with varying degrees of hypokalaemia and hypertension due to primary sodium retention. We report here a case of Liddle’s syndrome due to a novel c.1709del11 (p.Ser570Tyrfs*20) deletion in the beta-subunit of the ENaC in a young black African male. We discuss the likely pathogenesis of hypertension in this setting as well as the treatment options available in South Africa aimed at the ENaC. This case highlights the need for vigilance in detecting and appropriately treating low-renin and low-aldosterone hypertension in view of the frequency of the described variants of the ENaC channel in our cuntry. Specific therapy such as amiloride should be made more widely available.

Liddle syndrome (LS), a monogenetic autosomal dominant disorder, is mainly characterized by early-onset hypertension and hypokalemia. Clinically, misdiagnosis or missing diagnosis is common, since clinical phenotypes of LS are variable and nonspecific. We report a family with misdiagnosis of primary aldosteronism (PA), but identify as LS with a pathogenic frameshift mutation of the epithelial sodium channel (ENaC) β subunit. DNA samples were collected from a 32-year-old proband and 31 other relatives in the same family. A designed panel including 41 genes associated with monogenic hypertension was screened using next-generation sequencing. The best candidate disease-causing variants were verified by Sanger sequencing. Genetic analysis of the proband revealed a novel frameshift mutation c.1838delC (p.Pro613Glnfs*675) in exon 13 of SCNN1B. This heterozygous mutation involved the deletion of a cytosine from a string of three consecutive cytosines located at codons 612 to 613 and resulted in deletion of the crucial PY motif and elongation of the β-ENaC protein. The identical mutation was also found in 12 affected family members. Amiloride was effective in alleviating LS for patients. There were no SCNN1A or SCNN1G mutations in this family. Our study emphasizes the importance of considering LS in the differential diagnosis of early-onset hypertension. The identification of a novel frameshift mutation of SCNN1B enriches the genetic spectrum of LS and has allowed treatment of this affected family to prevent severe complications.

Pseudoaldosteronism is a common adverse effect associated with traditional Japanese Kampo medicines. The pathogenesis is mainly caused by 3-monoglucuronyl glycyrrhetinic acid (3MGA), one of the metabolites of glycyrrhizin (GL) contained in licorice. We developed an anti-3MGA monoclonal antibody (MAb) and an ELISA system to easily detect 3MGA in the plasma and urine of the patients. However, we found that some metabolites of GL cross-reacted with this MAb. Mrp2-deficient Eisai Hyperbilirubinemia rats (EHBRs) were administered glycyrrhetinic acid (GA), and we isolated 22α-hydroxy-18β-glycyrrhetyl-3-O-sulfate-30-glucuronide (1) from the pooled urine with the guidance of positive immunostaining of eastern blot as the new metabolite of GL. The IC50 of 1 for type 2 11β-hydroxysteroid dehydrogenase (11β-HSD2) was 2.0 µM. Similar plasma concentrations of 1 and GA were observed 12 h after oral administration of GA to EHBR. Compound 1 was eliminated via urine, whereas GA was not. In Sprague–Dawley (SD) rats orally treated with GA, compound 1 was absent from both the plasma and the urine. Compound 1 was actively transported into cells via OAT1 and OAT3, whereas GA was not. Compound 1, when produced in Mrp2-deficiency, represents a potential causative agent of pseudoaldosteronism, and might be used as a biomarker to prevent the adverse effect.

Background Liddle’s syndrome is a rare monogenic form of hypertension caused by truncating or missense mutations in the C termini of the epithelial sodium channel (ENaC) β or γ subunits. Patients with this syndrome present with early onset of hypertension, hypokalemia, metabolic alkalosis, hyporeninemia and hypoaldosteronism, and a potassium-sparing diuretics (triamterene or amiloride) can drastically improves the disease condition. Although elderly patients having these characteristics were considered to have Liddle’s syndrome or Liddle’s-like syndrome, no previous report has indicated that Liddle’s-like syndrome could be caused by nephrotic syndrome of primary glomerular disease, which is characterized by urinary excretion of > 3 g of protein/day plus edema and hypoalbuminemia, or has explained how the activity function of ENaC could be affected in the setting of high proteinuria. Case presentation A 65-year-old Japanese man presented with nephrotic syndrome. He had no remarkable family history, but had a medical history of hypertension and hyperlipidemia. On admission, hypertension, spironolactone-resistant hypokalemia (2.43 mEq/l), hyporeninemic hypoaldosteronism, and metabolic alkalosis, which suggested Liddle’s syndrome, were observed. Treatment with triamterene together with a steroid for nephrotic syndrome resulted in rapid and remarkable effective on improvements of hypertension, hypokalemia, and edema of the lower extremities. Renal biopsy revealed membranous nephropathy (MN) as the cause of nephrotic syndrome, and advanced gastric cancer was identified on screening examination for cancers that could be associated with the development of MN. After total gastrectomy, triamterene was not required and proteinuria decreased. A mutation in the β or γ subunits of the ENaC gene was not identified. Conclusion We reported for the first time a case of Liddle’s-like syndrome associated with nephrotic syndrome secondary to MN. Aberrant activation of ENaC was suggested transient during the period of high proteinuria, and the activation was reversible with a decrease in proteinuria.

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.

Increased blood pressure in children is usually secondary to a known cause. It is very important to discover the cause of high blood pressure, to treat it before the development of complications, and to prevent morbidity and mortality at this age. In this article, we will present a case of a 10-years-old girl with increased blood pressure and hypokalemia, we have been excluded any other causes for the high blood pressure, and after a favorable response to appropriate treatment, Amiloride, with a supportive laboratory, she was diagnosed with Liddle Syndrome.

Monogenic (Mendelian) forms of hypertension provide important insight into mechanisms of blood pressure regulation. Frequently, they are caused by increased salt reabsorption in the kidney via activation of the mineralocorticoid signaling pathway, which includes Liddle syndrome, glucocorticoid-remediable aldosteronism, apparent mineralocorticoid excess, and salt-sensitive congenital adrenal hyperplasia. In pseudohypoaldosteronism type II, salt-sensitive hypertension is linked with a distinctive decrease in renal potassium excretion leading to hyperkalemia. Other mechanisms in monogenic hypertension are sympathetic nervous system hyperactivity (hereditary forms of pheochromocytoma) and altered vascular resistance (hypertension brachydactyly syndrome). Complementary studies examining monogenic forms of lower blood pressure have identified pathways exclusively linked to renal salt wasting due to altered tubular function in the thick ascending limb (Bartter syndrome) or distal nephron (Gitelman syndrome, EAST syndrome). This chapter delineates the genetic mechanisms underlying rare abnormal blood pressure syndromes, providing important implications on improving diagnosis and treatment of blood pressure disorders.

Background: Liddle syndrome is an autosomal dominant form of monogenic hypertension. Phenotypic variability makes it difficult to identify patients with Liddle syndrome, resulting in misdiagnosis and severe complications at early age. Objectives: To identify mutation in SCNN1B and SCNN1G genes in an adolescent with suspicious Liddle syndrome and his family members and to explore the screening target subjects of Liddle syndrome. Methods: Genetic analysis of the C-terminus of SCNN1B and SCNN1G genes was conducted in an adolescent, with treatment-resistant hypertension and hypokalemia, who was suspected of having Liddle syndrome, and his family members. A Medline research of the reported cases with Liddle syndrome was also performed. Results: A recurrent SCNN1B mutation, c.1853C>A (p.P618H), was detected in the 19-year-old male patient, and family screening identified five additional members who were heterozygous for the mutation. The diagnosis of Liddle syndrome was made in all affected individuals. Despite the phenotypic variability, a systematic review of 54 reported index cases revealed the early-onset hypertension, aged no more than 30 years, as a common feature. Conclusions: Genetic screening for Liddle syndrome should be considered in hypertensive subjects with early penetrance, maybe no more than 30 years, after exclusion of common secondary causes of hypertension.

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.

Liddle syndrome is considered a rare Mendelian hypertension. We have previously described 3 reportedly unrelated families, native of an Italian area around the Strait of Messina, carrying the same mutation (βP617L) of the epithelial sodium channel. The aims of our study were (1) to evaluate whether a close genomic relationship exists between the 3 families through the analysis of mitochondrial DNA and Y chromosome; and (2) to quantify the genomic relatedness between the patients with Liddle syndrome belonging to the 3 families and assess the hypothesis of a mutation shared through identity by descent. HVRI (the hypervariable region I) of the mitochondrial DNA genome and the Y chromosome short tandem repeats profiles were analyzed in individuals of the 3 families. Genotyping 542 585 genome-wide single nucleotide polymorphisms was performed in all the patients with Liddle syndrome of the 3 families and some of their relatives. A panel of 780 healthy Italian adult samples typed for the same set of markers was used as controls. espite different lineages between the 3 families based on the analysis of mitochondrial DNA and Y chromosome, the 3 probands and their 6 affected relatives share the same ≈5 Mbp long haplotype which encompasses the mutant allele. Using an approach based on coalescent theory, we estimate that the 3 families inherited the mutant allele from a common ancestor ≈13 generations ago and that such an ancestor may have left ≈20 carriers alive today. The prevalence of Liddle syndrome in the region of origin of the 3 families may be much higher than that estimated worldwide.

Background Posaconazole is an extended-spectrum triazole used in the treatment and prophylaxis of many fungal diseases. There have been case reports of posaconazole-induced pseudohyperaldosteronism; however, its occurrence and association with serum posaconazole drug levels need further investigation. Methods In this single-center retrospective observational study, we examined the occurrence of posaconazole-induced pseudohyperaldosteronism (PIPH), diagnosed either clinically or via laboratory abnormalities, and evaluated differences in serum posaconazole concentration and clinical characteristics between those with and without this syndrome. Results Sixty-nine patients receiving posaconazole were included; of whom, 16 (23.2%) met the definition of PIPH. Patients with PIPH were significantly older (61.1 vs. 44.7 years, P = 0.007), more frequently had hypertension prior to starting posaconazole (68.8% vs. 32.1%, P = 0.009), and were more frequently prescribed posaconazole for active treatment instead of prophylaxis compared with patients without PIPH (62.5% vs. 24.5%, P = 0.005). Patients with PIPH had a significantly higher median serum posaconazole level than those without PIPH (3.0 vs. 1.2 µg/mL, P = 0.0001). There was a positive correlation between serum posaconazole level and change in systolic blood pressure (r = 0.37, P = 0.01), a negative correlation between serum posaconazole level and change in serum potassium (r = −0.39, P = 0.006), and a positive correlation between serum posaconazole level and serum 11-deoxycortisol (r = 0.69, P < 0.0001). Conclusion Posaconazole is associated with secondary hypertension and hypokalemia, consistent with pseudohyperaldosteronism, and development is associated with higher serum posaconazole concentrations, older age, and baseline hypertension. Management may include dose reduction, the addition of an aldosterone antagonist, or an alternative triazole agent. Disclosures All authors: No reported disclosures.

Aldosterone plays an essential role in the maintenance of fluid and electrolyte homeostasis in the distal nephron. Monogenic forms of mineralocorticoid hypertension result from genetic defects leading to excessive production of aldosterone (or other mineralocorticoids) from the adrenal cortex or to illegitimate mineralocorticoid effects in the kidney. They are characterized in the majority of cases by early onset, severe or resistant hypertension and associated with suppressed renin levels. Depending on their causes, these diseases are distinguished at the clinical and biochemical level and differently affect aldosterone levels and kalemia. The diagnosis is confirmed by genetic testing, which allows in many cases targeted treatment to prevent severe cardiovascular consequences of high blood pressure or aldosterone excess. In this review we describe the different forms of inherited mineralocorticoid hypertension, providing an overview of their clinical and biochemical features, their underlying genetic defects and specific therapeutic options.

In daily clinical practice, the term electrolyte generally refers to sodium, potassium, chloride, calcium, and magnesium ions. In addition to their many functions, such as neuronal and muscular transmission, some electrolytes also contribute to osmolality and maintenance of electrochemical gradients, which, in turn enable many transport processes. The absorption and reabsorption of electrolytes occurs via polarized cell assemblies, i.e., epithelia. Besides the intestine (absorption), the most important organ is the kidney. Here, following glomerular filtration, electrolytes are reabsorbed via trans- and paracellular mechanisms along the renal tubular system. In the past, the identification and elucidation of transport-associated monogenetic disorders has contributed tremendously to our understanding of the physiology and pathophysiology of such transport mechanisms. Sodium reabsorption mechanisms along the tubular system have been characterized by means of pharmacological compounds for a long time. However, only with the development of novel molecular genetic tools and approaches has it been possible to clarify the genetic basis of distinct diseases. As examples, we discuss here Bartter and Gitelman syndrome, and other sodium disorders such as pseudohypoaldosteronism and Liddle Syndrome. Diagnosis, clinical presentation, and therapy are briefly described. Furthermore, examples of magnesium homeostasis disorders are also presented, the molecular mechanisms and pathophysiology of which could also be characterized by the identification of different human mutations.

The study aimed to analyze genes involved in Mendelian forms of low-renin hypertension in Chinese early-onset hypertensive patients.A panel of nine genes, namely SCNN1B, SCNN1G, WNK1, WNK4, KLHL3, CUL3, nuclear receptor subfamily 3, group C (NR3C)1, NR3C2, and HSD11B2 were screened by targeted resequencing in 260 Chinese early-onset hypertensive patients. Additionally, exon 13 of both SCNN1B and SCNN1G was sequenced in an independent cohort of 506 Chinese early-onset hypertensive patients.About 81 nonrare and 41 rare variants were, respectively, detected in 221 (85.0%) and 39 (15.0%) patients from the cohort of 260. Of the total 766 patients, those with rare variants in exon 13 of either SCNN1B or SCNN1G had a significantly earlier onset of hypertension (24.7 ± 7.5 vs. 29.0 ± 7.7 years, P = 0.015) and lower serum potassium (3.57 ± 0.59 vs. 3.96 ± 0.41 mmol/l, P = 0.007) than those without rare variants. However, other identified rare variants had no effects on clinical expression. Seven patients (0.91%) were diagnosed with Liddle's syndrome, and the Liddle's syndrome prevalence was 1.72% among the 407 patients with hypertension diagnosed before the age of 30. Genetic screening of the probands' relatives identified 10 additional Liddle's syndrome patients. Treatment of Liddle's syndrome patients with amiloride resulted in normalization of both blood pressure and serum potassium.Liddle's syndrome appears to be the most common low-renin Mendelian hypertension in young Chinese hypertensive patients. Sequencing exon 13 of both SCNN1B and SCNN1G is highly advisable in patients with early-onset and low-renin hypertension.

Liddle syndrome is a rare form of autosomal dominant monogenic hypertension manifested as an early onset of resistant hypertension with either no response or suboptimal response to conventional antihypertensive therapy. If there is a delay in diagnosis, uncontrolled hypertension can lead to end organ damage. To our knowledge, aortic dissection has not been reported in association with this disease. We report a case of a dissecting aortic aneurysm occurring in association with Liddle syndrome.​.

Liddle syndrome is an autosomal dominant genetic condition that causes hypertension and hypokalemia due to a gain-of-function mutation in the SCNN1B or SCNN1G genes which code for the epithelial sodium channel in the kidney. This leads to increased sodium and water reabsorption causing hypertension. We report a case of a 27-year-old pregnant woman who was admitted for hypertension and hypokalemia and later diagnosed and treated for Liddle syndrome using amiloride. Maintaining a high suspicion of Liddle syndrome in pregnancy is essential in such cases to be able to adequately and effectively treat the hypertension. Due to physiological effects of pregnancy, the dose of amiloride may need to be increased as gestational age progresses up to a maximum dose of 30 mg orally per day.

The pathogenesis of licorice-induced pseudoaldosteronism is thought to involve the inhibition of 11β-hydroxysteroid dehydrogenase type 2 by glycyrrhetinic acid. Some risk factors have been reported, but differences between Japan and other countries have not been reported.A 79-year-old woman was hospitalized because of pseudoaldosteronism with rhabdomyolysis caused by ingestion of herbal medicines containing licorice. She had been prescribed shakuyakukanzobushito (decocted, 3 g of licorice) and keishikajutsubuto (decocted, 2 g of licorice) for the treatment of lower back pain and had been taking antihypertensive agents for the treatment of essential hypertension. After taking the herbal medicines for 2 weeks, the patient developed weakness of the extremities and pain in both thighs. On admission, she had hypertension, oliguria, an elevated serum creatine kinase level, hypokalemia, alkalemia associated with metabolic alkalosis, low plasma renin activity, and low plasma aldosterone levels. Intravenous and oral potassium supplementation and the administration of spironolactone resulted in the normalization of her condition within approximately 2 weeks.An analysis of case reports of pseudoaldosteronism with rhabdomyolysis revealed that in Japan, most cases occurred in elderly women with essential hypertension and were caused by drugs such as herbal medicines. In contrast, in other countries, many cases involved younger men, and the dominant causes were foods containing licorice. The use of herbal medicines is increasing all over the world, and when a patient with risk factors is prescribed an herbal medicine containing licorice, careful follow-up is required.

Hypokalaemia with alkalosis can suggest excess aldosterone. Aldosterone stimulates the collecting duct mineralocorticoid receptor (MR) to upregulate the epithelial sodium channel (ENaC) and stimulate electrogenic sodium reabsorption, with secretion of potassium and protons. Gitelman, Bartter and Liddle syndrome, and liquorice ingestion all cause hypokalaemic alkalosis. This mini-review outlines the pathophysiology of these conditions as well as how to differentiate them.

BACKGROUND Liddle syndrome (LS) is an autosomal dominant disorder caused by single-gene mutations of the epithelial sodium channel (ENaC). It is characterized by early-onset hypertension, spontaneous hypokalemia and low plasma renin and aldosterone concentrations. In this study, we reported an LS pedigree with normokalemia resulting from a novel SCNN1G frameshift mutation. METHODS Peripheral blood samples were collected from the proband and eight family members for DNA extraction. Next-generation sequencing and Sanger sequencing were performed to identify the SCNN1G mutation. Clinical examinations were used to comprehensively evaluate the phenotypes of two patients. RESULTS Genetic analysis identified a novel SCNN1G frameshift mutation, p.Arg586Valfs*598, in the proband with LS. This heterozygous frameshift mutation generated a premature stop codon and deleted the vital PY motif of ENaC. The same mutation was present in his elder brother with LS, and his mother without any LS symptoms. Biochemical examination showed normokalemia in the three mutation carriers. The mutation identified was not found in any other family members, 100 hypertensives, or 100 healthy controls. CONCLUSIONS Our study identified a novel SCNN1G frameshift mutation in a Chinese family with LS, expanding the genetic spectrum of SCNN1G. Genetic testing helped us identify LS with a pathogenic mutation when the genotypes and phenotype were not completely consistent because of the hypokalemia. This case emphasizes that once a proband is diagnosed with LS by genetic testing, family genetic sequencing is necessary for early diagnosis and intervention for other family members, to protect against severe cardiovascular complications.