Frequency of Familial Hyperaldosteronism Type 1 in a Hypertensive Pediatric Population

Familial hyperaldosteronism: an European Reference Network on Rare Endocrine Conditions clinical practice guideline

We describe herein the European Reference Network on Rare Endocrine Conditions clinical practice guideline on diagnosis and management of familial forms of hyperaldosteronism. The guideline panel consisted of 10 experts in primary aldosteronism, endocrine hypertension, paediatric endocrinology, and cardiology as well as a methodologist. A systematic literature search was conducted, and because of the rarity of the condition, most recommendations were based on expert opinion and small patient series. The guideline includes a brief description of the genetics and molecular pathophysiology associated with each condition, the patients to be screened, and how to screen. Diagnostic and treatment approaches for patients with genetically determined diagnosis are presented. The recommendations apply to patients with genetically proven familial hyperaldosteronism and not to families with more than one case of primary aldosteronism without demonstration of a responsible pathogenic variant.

Differences in the clinical and hormonal presentation of patients with familial and sporadic primary aldosteronism

Purpose

To compare the clinical and hormonal characteristics of patients with familial hyperaldosteronism (FH) and sporadic primary aldosteronism (PA).

Methods

A systematic review of the literature was performed for the identification of FH patients. The SPAIN-ALDO registry cohort of patients with no suspicion of FH was chosen as the comparator group (sporadic group).

Results

A total of 360 FH (246 FH type I, 73 type II, 29 type III, and 12 type IV) cases and 830 sporadic PA patients were included. Patients with FH-I were younger than sporadic cases, and women were more commonly affected (P = 0.003). In addition, the plasma aldosterone concentration (PAC) was lower, plasma renin activity (PRA) higher, and hypokalemia (P < 0.001) less frequent than in sporadic cases. Except for a younger age (P < 0.001) and higher diastolic blood pressure (P = 0.006), the clinical and hormonal profiles of FH-II and sporadic cases were similar. FH-III had a distinct phenotype, with higher PAC and higher frequency of hypokalemia (P < 0.001), and presented 45 years before sporadic cases. Nevertheless, the clinical and hormonal phenotypes of FH-IV and sporadic cases were similar, with the former being younger and having lower serum potassium levels.

Conclusion

In addition to being younger and having a family history of PA, FH-I and III share other typical characteristics. In this regard, FH-I is characterized by a low prevalence of hypokalemia and FH-III by a severe aldosterone excess causing hypokalemia in more than 85% of patients. The clinical and hormonal phenotype of type II and IV is similar to the sporadic cases.

Therapeutic management of congenital forms of endocrine hypertension

Congenital forms of endocrine hypertension are rare and potentially life-threatening disorders, primarily caused by genetic defects affecting adrenal steroid synthesis and activation pathways. These conditions exhibit diverse clinical manifestations, which can be distinguished by their unique molecular mechanisms and steroid profiles. Timely diagnosis and customized management approach are crucial to mitigate unfavorable outcomes associated with uncontrolled hypertension and other related conditions. Treatment options for these disorders depend on the distinct underlying pathophysiology, which involves specific pharmacological therapies or surgical adrenalectomy in some instances. This review article summarizes the current state of knowledge on the therapeutic management of congenital forms of endocrine hypertension, focusing on familial hyperaldosteronism (FH), congenital adrenal hyperplasia, apparent mineralocorticoid excess, and Liddle syndrome. We provide an overview of the genetic and molecular pathogenesis underlying each disorder, describe the clinical features, and discuss the various therapeutic approaches available and their risk of adverse effects, aiming to improve outcomes in patients with these rare and complex conditions.

Hypertension in children and adolescents

Definition and management of arterial hypertension in children and adolescents are uncertain, due to different positions of current guidelines. The European Society of Cardiology task-force, constituted by Associations and Councils with interest in arterial hypertension, has reviewed current literature and evidence, to produce a Consensus Document focused on aspects of hypertension in the age range of 6-16 years, including definition, methods of measurement of blood pressure, clinical evaluation, assessment of hypertension-mediated target organ damage, evaluation of possible vascular, renal and hormonal causes, assessment and management of concomitant risk factors with specific attention for obesity, and anti-hypertensive strategies, especially focused on life-style modifications. The Consensus Panel also suggests aspects that should be studied with high priority, including generation of multi-ethnic sex, age and height specific European normative tables, implementation of randomized clinical trials on different diagnostic and therapeutic aspects, and long-term cohort studies to link with adult cardiovascular risk. Finally, suggestions for the successful implementation of the contents of the present Consensus document are also given.

Monogenic forms of low-renin hypertension: clinical and molecular insights

Monogenic disorders of hypertension are a distinct group of diseases causing dysregulation of the renin-angiotensin-aldosterone system and are characterized by low plasma renin activity. These can chiefly be classified as causing (i) excessive aldosterone synthesis (familial hyperaldosteronism), (ii) dysregulated adrenal steroid metabolism and action (apparent mineralocorticoid excess, congenital adrenal hyperplasia, activating mineralocorticoid receptor mutation, primary glucocorticoid resistance), and (iii) hyperactivity of sodium and chloride transporters in the distal tubule (Liddle syndrome and pseudohypoaldosteronism type 2). The final common pathway is plasma volume expansion and catecholamine/sympathetic excess that causes urinary potassium wasting; hypokalemia and early-onset refractory hypertension are characteristic. However, several single gene defects may show phenotypic heterogeneity, presenting with mild hypertension with normal electrolytes. Evaluation is based on careful attention to family history, physical examination, and measurement of blood levels of potassium, renin, and aldosterone. Genetic sequencing is essential for precise diagnosis and individualized therapy. Early recognition and specific management improves prognosis and prevents long-term sequelae of severe hypertension.

Japan Endocrine Society clinical practice guideline for the diagnosis and management of primary aldosteronism 2021

Primary aldosteronism (PA) is associated with higher cardiovascular morbidity and mortality rates than essential hypertension. The Japan Endocrine Society (JES) has developed an updated guideline for PA, based on the evidence, especially from Japan. We should preferentially screen hypertensive patients with a high prevalence of PA with aldosterone to renin ratio ≥200 and plasma aldosterone concentrations (PAC) ≥60 pg/mL as a cut-off of positive results. While we should confirm excess aldosterone secretion by one positive confirmatory test, we could bypass patients with typical PA findings. Since PAC became lower due to a change in assay methods from radioimmunoassay to chemiluminescent enzyme immunoassay, borderline ranges were set for screening and confirmatory tests and provisionally designated as positive. We recommend individualized medicine for those in the borderline range for the next step. We recommend evaluating cortisol co-secretion in patients with adrenal macroadenomas. Although we recommend adrenal venous sampling for lateralization before adrenalectomy, we should carefully select patients rather than all patients, and we suggest bypassing in young patients with typical PA findings. A selectivity index ≥5 and a lateralization index >4 after adrenocorticotropic hormone stimulation defines successful catheterization and unilateral subtype diagnosis. We recommend adrenalectomy for unilateral PA and mineralocorticoid receptor antagonists for bilateral PA. Systematic as well as individualized clinical practice is always warranted. This JES guideline 2021 provides updated rational evidence and recommendations for the clinical practice of PA, leading to improved quality of the clinical practice of hypertension.

GRAde: a long-read sequencing approach to efficiently identifying the CYP11B1/CYP11B2 chimeric form in patients with glucocorticoid-remediable aldosteronism

BACKGROUND

Glucocorticoid-remediable aldosteronism (GRA) is a form of heritable hypertension caused by a chimeric fusion resulting from unequal crossing over between 11β-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2), which are two genes with similar sequences. Different crossover patterns of the CYP11B1 and CYP11B2 chimeric genes may be associated with a variety of clinical presentations. It is therefore necessary to develop an efficient approach for identifying the differences between the hybrid genes of a patient with GRA.

RESULTS

We developed a long-read analysis pipeline named GRAde (GRA deciphering), which utilizes the nonidentical bases in the CYP11B1 and CYP11B2 genomic sequences to identify and visualize the chimeric form. We sequenced the polymerase chain reaction (PCR) products of the CYP11B1/CYP11B2 chimeric gene from 36 patients with GRA using the Nanopore MinION device and analyzed the sequences using GRAde. Crossover events were identified for 30 out of the 36 samples. The crossover sites appeared in the region exhibiting high sequence similarity between CYP11B1 and CYP11B2, and 53.3% of the cases were identified as having a gene conversion in intron 2. More importantly, there were six cases for whom the PCR products indicated a chimeric gene, but the GRAde results revealed no crossover pattern. The crossover regions were further verified by Sanger sequencing analysis.

CONCLUSIONS

PCR-based target enrichment followed by long-read sequencing is an efficient and precise approach to dissecting complex genomic regions, such as those involved in GRA mutations, which could be directly applied to clinical diagnosis. The scripts of GRAde are available at https://github.com/hsu-binfo/GRAde .

Characteristics and Outcomes in Primary Aldosteronism Patients Harboring Glucocorticoid-Remediable Aldosteronism

The clinical characteristics and surgical prognosis of glucocorticoid-remediable aldosteronism (GRA, also known as familial hyperaldosteronism type 1, FH-I) have not been widely studied. Using data from the Taiwan Primary Aldosteronism Investigation (TAIPAI) registry retrospectively, we describe the associated clinical factors for GRA and clinical predictors of surgical outcomes among identified GRA patients. We found 79 GRA-positive (51.2 ± 13.8 years; women 39 (49.4%)) and 114 GRA-negative primary aldosteronism (PA) patients matched with age, gender, and body mass index. Lower plasma aldosterone concentrations (PACs) and aldosterone-renin ratios were found among GRA-positive individuals. Multivariable logistic regression demonstrated that a PAC ≤ 40 ng/dL could predict concealed GRA individuals (OR 0.523, p = 0.037). Low serum potassium (OR 0.285, p = 0.008), but not the presence of GRA, was associated with hypertension-remission. Of note, PRA (OR 11.645, p = 0.045) and hypokalemia (OR 0.133, p = 0.048) were associated with hypertension-remission in GRA patients. Unilateral primary aldosteronism patients harboring concomitant GRA were not associated with inferior hypertension-remission after an adrenalectomy. Low serum potassium and high PRA were positively associated with hypertension-remission in GRA patients.

Urinary sodium-to-potassium ratio and plasma renin and aldosterone concentrations in normotensive children: implications for the interpretation of results

OBJECTIVES

To identify associations among the plasma renin concentration (PRC), plasma aldosterone and urinary sodium (Na)/potassium (K) ratio, and to integrate these variables into a nomogram with the aim of estimating the expected versus observed aldosterone concentration.

METHODS

We studied 40 healthy normotensive children (5-8 years old, 57.5% girls) who were born at term and were adequate for their gestational age. Following overnight fasting, the PRC and plasma aldosterone in blood samples were measured, and the Na/K ratio was calculated from a simultaneously obtained urinary spot sample. A mathematical function was defined with these three variables, and a nomogram was built that would return the expected aldosterone concentration from the obtained plasma renin and urinary Na/K ratio values.

RESULTS

The PRC (B =  5.9, P < 0.001) and urinary Na/K ratio (B = -98.1, P = 0.003) were significant independent predictors of plasma aldosterone. The correlation between the observed plasma aldosterone and the expected plasma aldosterone, as obtained from the nomogram, was r = 0.88, P < 0.001. The average difference between the observed and expected plasma aldosterone was -0.89, with a standard deviation of ±30%.

CONCLUSION

The strong correlation between the urinary Na/K ratio, from urine samples taken at the same as the blood samples, and plasma renin and aldosterone concentrations allowed us to build a nomogram to predict aldosterone levels. This approach may be useful for evaluating the renin-angiotensin-aldosterone system (RAAS) in pediatric patients with hypertension and RAAS dysfunction.

Familial Aggregation and Heritability of Aldosteronism with Cardiovascular Events

CONTEXT

To date, the effect of positive family history as a risk factor of primary aldosteronism (PA) is largely unknown. Studies have failed to distinguish the heritability of PA as well as the associations between positive family history of PA and clinical outcomes.

OBJECTIVES

We quantified the prevalence, the extent of familial aggregation, the heritability of PA among family members of patients with PA, and the association between positive PA family history and major cardiovascular events (MACE).

DESIGN AND SETTINGS

Using the Taiwan National Health Insurance Database, 30 245 077 National Health Insurance beneficiaries (both alive and those deceased between January 1, 1999, and December 31, 2015) were identified.

RESULTS

We identified 7902 PA patients. Forty-four had PA (0.3%) among 10 234 individuals with affected parents, 2298 with affected offspring, 1924 with affected siblings, and 22 with affected twins. A positive family history was associated with the adjusted relative risk (RR) (95% confidence interval [CI]) of 11.60 (7.63-17.63) for PA in people with an affected first-degree relative. In subgroup analysis, the risk for PA across all relationships (parent, siblings, offspring, and spouse) showed highly significant differences to PA without family history. The accountability for phenotypic variance of PA was 51.0% for genetic factors, 24.9% for shared environmental factors, and 24.1% for nonshared environmental factors. PA patients with an affected first-degree relative were associated with an increased risk for composite major cardiovascular events (RR 1.31; 95% CI 1.24-1.40, P < .001) compared with PA patients without family history.

CONCLUSION

Familial clustering of PA exists among a population-based study, supporting a genetic susceptibility leading to PA. There is increased coaggregation of MACE in first-degree relatives of PA patients. Our findings suggest a strong genetic component in the susceptibility of PA, involving different kinships.

Old and new genes in primary aldosteronism

Primary aldosteronism (PA) is the most common form of secondary hypertension affecting 5%-10% of patients with arterial hypertension. In PA, high blood pressure is associated with high aldosterone and low renin levels, and often hypokalemia. In a majority of cases, autonomous aldosterone production by the adrenal gland is caused by an aldosterone producing adenoma (APA) or bilateral adrenal hyperplasia (BAH). During the last ten years, a better knowledge of the pathophysiology of PA came from the discovery of somatic and germline mutations in different genes in both sporadic and familial forms of the disease. Those genes code for ion channels and pumps, as well as proteins involved in adrenal cortex development and function. Targeted next generation sequencing following immunohistochemistry guided detection of aldosterone synthase expression allows detection of somatic mutations in up to 90% of APA, while whole exome sequencing has discovered the genetic causes of four different familial forms of PA. The identification, in BAH, of somatic mutations in aldosterone producing cell clusters open new perspectives in our understanding of the bilateral form of the disease and the development of new therapeutic approaches.

Monogene Formen der arteriellen Hypertonie

Hintergrund

Die Grundlage der arteriellen Hypertonie bei der überwiegenden Mehrzahl der Patienten ist multifaktorieller, zum großen Teil umweltbedingter Genese und derzeit in der Routinediagnostik nicht sinnvoll molekulargenetisch untersuchbar. Bei einem kleinen Teil der Patienten (<1 %) ist die arterielle Hypertonie aber Folge hereditärer, monogener Defekte. Hierzu gehören das Liddle-Syndrom, familiärer Hyperaldosteronismus, apparenter Mineralkortikoidexzess und Pseudohypoaldosteronismus. Diese und andere hereditäre Hypertonien gehen pathomechanistisch auf Störungen in den renalen Regelkreisen der Elektrolyt- und Volumenhomöostase zurück.

Ziel der Arbeit

Die bekannten Typen der hereditären Hypertonien sollen verständlich und schematisch erläutert werden. Besonderer Fokus liegt dabei auch auf dem klinischen Bild der jeweiligen Unterformen sowie der therapeutischen Konsequenz, die sich in dieser Krankheitsgruppe direkt aus dem molekulargenetischen Befund ergeben kann. Eine Auswahl weiterer genetischer Syndrome mit arterieller Hypertonie als Begleit- oder Spätsymptom wird zusammenfassend behandelt.

Fazit

Die korrekte Diagnose eines Betroffenen mit einer Form der hier beschriebenen hereditären Hypertonien ermöglicht eine gezielte und effektive medikamentöse Therapie auf Basis der inzwischen insgesamt gut verstandenen jeweiligen Pathomechanismen.

Serum Cortisol and Cortisone as Potential Biomarkers of Partial 11β-Hydroxysteroid Dehydrogenase Type 2 Deficiency

BACKGROUND

Pathogenic variations in HSD11B2 gene triggers the apparent mineralocorticoid excess syndrome (AME). There is scarce information regarding the phenotypes of subjects carrying heterozygous pathogenic variants in HSD11B2 gene. We investigated if serum cortisol/cortisone (F/E) ratio and cortisone are useful for identifying partial 11βHSD2 deficiency in those heterozygous subjects.

METHODS

We studied two patients diagnosed with AME and their families carrying either D223N or R213C mutation. We also evaluated 32 healthy control subjects (13 children and 19 adults) to obtain normal references ranges for all measured variables. Case 1: A boy carrying D223N mutation in HSD11B2 gene and Case 2: A girl carrying R213C mutation. We assessed serum F/E ratio and cortisone by HPLC-MS/MS, aldosterone, plasma-renin-activity(PRA), electrolytes, and HSD11B2 genetic analyses.

RESULTS

The normal values (median [interquartile range]) in children for serum F/E and cortisone (µg/dl) were 2.56 [2.21-3.69] and 2.54 [2.35-2.88], and in adults were 4.42 [3.70-4.90] and 2.23 [1.92-2.57], respectively. Case 1 showed a very high serum F/E 28.8 and low cortisone 0.46 µg/dl. His mother and sister were normotensives and heterozygous for D223N mutation with high F/E (13.2 and 6.0, respectively) and low cortisone (2.0 and 2.2, respectively). Case 2 showed a very high serum F/E 175 and suppressed cortisone 0.11 µg/dl. Her parents and sister were heterozygous for the R213C mutation with normal phenotype, but high F/E and low cortisone. Heterozygous subjects showed normal aldosterone, PRA, but lower fractional excretion of sodium and urinary Na/K ratio than controls.

CONCLUSION

Serum F/E ratio and cortisone allow to identify partial 11βHSD2 deficiencies, as occurs in heterozygous subjects, who would be susceptible to develop arterial hypertension.

Genetic Causes of Functional Adrenocortical Adenomas

Aldosterone and cortisol, the main mineralocorticoid and glucocorticoid hormones in humans, are produced in the adrenal cortex, which is composed of three concentric zones with specific functional characteristics. Adrenocortical adenomas (ACAs) can lead to the autonomous secretion of aldosterone responsible for primary aldosteronism, the most frequent form of secondary arterial hypertension. In the case of cortisol production, ACAs lead to overt or subclinical Cushing syndrome. Genetic analysis driven by next-generation sequencing technology has enabled the discovery, during the past 7 years, of the genetic causes of a large subset of ACAs. In particular, somatic mutations in genes regulating intracellular ionic homeostasis and membrane potential have been identified in aldosterone-producing adenomas. These mutations all promote increased intracellular calcium concentrations, with activation of calcium signaling, the main trigger for aldosterone production. In cortisol-producing adenomas, recurrent somatic mutations in PRKACA (coding for the cyclic adenosine monophosphate-dependent protein kinase catalytic subunit α) affect cyclic adenosine monophosphate-dependent protein kinase A signaling, leading to activation of cortisol biosynthesis. In addition to these specific pathways, the Wnt/β-catenin pathway appears to play an important role in adrenal tumorigenesis, because β-catenin mutations have been identified in both aldosterone- and cortisol-producing adenomas. This, together with different intermediate states of aldosterone and cortisol cosecretion, raises the possibility that the two conditions share a certain degree of genetic susceptibility. Alternatively, different hits might be responsible for the diseases, with one hit leading to adrenocortical cell proliferation and nodule formation and the second specifying the hormonal secretory pattern.

Monogenic Hypertension in Children: A Review With Emphasis on Genetics

Hypertension (HT) is a public health problem in children particularly related to the epidemic of overweight and obesity. Monogenic forms of HT are important in the differential diagnosis in children presenting with severe or refractory HT, who have a family history of early-onset HT, unusual physical examination findings, and/or characteristic hormonal and biochemical abnormalities. Most genetic defects in these disorders ultimately result in increased sodium transport in the distal nephron resulting in volume expansion and HT. Genetic testing, which is increasingly available, has diagnostic, therapeutic, and predictive implications for families affected by these rare conditions.

Cortisol/cortisone ratio and matrix metalloproteinase-9 activity are associated with pediatric primary hypertension

OBJECTIVE

To identify novel biomarkers associated with pediatric primary hypertension.

METHODS

We recruited 350 participants (4-16 years). Anthropometric parameters and aldosterone, plasma renin activity, cortisol, cortisone, Homeostasis Model Assessment Insulin Resistance (HOMA-IR), high-sensitivity C-reactive protein, adiponectin, IL-6, plasminogen activator inhibitor type 1 levels and matrix metalloproteinase-9 and matrix metalloproteinase-2 (MMP-9 and MMP-2) activities were measured. Genomic DNA was isolated. Patients with altered glucose metabolism, severe obesity [BMI-SD score (BMI-SDS) > 2.5], renovascular disease, primary aldosteronism and apparent mineralocorticoid excess syndrome were excluded.

RESULTS

In selected participants (n = 320), SBP was positively correlated with BMI-SDS (r = 0.382, P < 0.001), HOMA-IR (r = 0.211, P < 0.001), MMP-9 activity (r = 0.215, P < 0.001) and the cortisol/cortisone ratio (r = 0.231, P < 0.001). DBP showed similar correlations with these variables. No correlation was observed with aldosterone or plasma renin activity. Participants were categorized as hypertensive (n = 59) or nonhypertensive (n = 261). In the univariate analysis, hypertensive patients had higher BMI-SDS (P < 0.001), HOMA-IR (P < 0.001), high-sensitivity C-reactive protein (P < 0.001), MMP-9 activity (P < 0.001), plasminogen activator inhibitor type 1 (P < 0.001) and cortisol/cortisone ratio (P < 0.001) than nonhypertensive patients. Multiple regression analysis showed that the variables that remained associated with hypertension were higher BMI-SDS [odds ratio (OR) = 3.74; 95% confidence interval (CI) = 1.84-7.58], a higher cortisol/cortisone ratio (OR = 3.92; 95% CI = 1.98-7.71) and increased MMP-9 activity (OR = 4.23; 95% CI = 2.15-8.32).

CONCLUSION

We report that MMP-9 activity and the cortisol/cortisone ratio were higher in pediatric primary hypertensive patients, and these associations were independent of the effect of obesity. The potential role of these novel biomarkers in predicting hypertension risk and blood pressure regulation warrants further investigation.

Clinical Practice Guideline for Screening and Management of High Blood Pressure in Children and Adolescents

These pediatric hypertension guidelines are an update to the 2004 "Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents." Significant changes in these guidelines include (1) the replacement of the term "prehypertension" with the term "elevated blood pressure," (2) new normative pediatric blood pressure (BP) tables based on normal-weight children, (3) a simplified screening table for identifying BPs needing further evaluation, (4) a simplified BP classification in adolescents ≥13 years of age that aligns with the forthcoming American Heart Association and American College of Cardiology adult BP guidelines, (5) a more limited recommendation to perform screening BP measurements only at preventive care visits, (6) streamlined recommendations on the initial evaluation and management of abnormal BPs, (7) an expanded role for ambulatory BP monitoring in the diagnosis and management of pediatric hypertension, and (8) revised recommendations on when to perform echocardiography in the evaluation of newly diagnosed hypertensive pediatric patients (generally only before medication initiation), along with a revised definition of left ventricular hypertrophy. These guidelines include 30 Key Action Statements and 27 additional recommendations derived from a comprehensive review of almost 15 000 published articles between January 2004 and July 2016. Each Key Action Statement includes level of evidence, benefit-harm relationship, and strength of recommendation. This clinical practice guideline, endorsed by the American Heart Association, is intended to foster a patient- and family-centered approach to care, reduce unnecessary and costly medical interventions, improve patient diagnoses and outcomes, support implementation, and provide direction for future research.

Somatic and inherited mutations in primary aldosteronism

Primary aldosteronism (PA), the most common form of secondary hypertension, is caused in the majority of cases by unilateral aldosterone-producing adenoma (APA) or bilateral adrenal hyperplasia. Over the past few years, somatic mutations in KCNJ5, CACNA1D, ATP1A1 and ATP2B3 have been proven to be associated with APA development, representing more than 50% of sporadic APA. The identification of these mutations has allowed the development of a model for APA involving modification on the intracellular ionic equilibrium and regulation of cell membrane potential, leading to autonomous aldosterone overproduction. Furthermore, somatic CTNNB1 mutations have also been identified in APA, but the link between these mutations and APA development remains unknown. The sequence of events responsible for APA formation is not completely understood, in particular, whether a single hit or a double hit is responsible for both aldosterone overproduction and cell proliferation. Germline mutations identified in patients with early-onset PA have expanded the classification of familial forms (FH) of PA. The description of germline KCNJ5 and CACNA1H mutations has identified FH-III and FH-IV based on genetic findings; germline CACNA1D mutations have been identified in patients with very early-onset PA and severe neurological abnormalities. This review summarizes current knowledge on the genetic basis of PA, the association of driver gene mutations and clinical findings and in the contribution to patient care, plus the current understanding on the mechanisms of APA development.

Genetics of primary hyperaldosteronism

Hypertension is a common medical condition and affects approximately 20% of the population in developed countries. Primary aldosteronism is the most common form of secondary hypertension and affects 8-13% of patients with hypertension. The two most common causes of primary aldosteronism are aldosterone-producing adenoma and bilateral adrenal hyperplasia. Familial hyperaldosteronism types I, II and III are the known genetic syndromes, in which both adrenal glands produce excessive amounts of aldosterone. However, only a minority of patients with primary aldosteronism have one of these syndromes. Several novel susceptibility genes have been found to be mutated in aldosterone-producing adenomas: KCNJ5, ATP1A1, ATP2B3, CTNNB1, CACNA1D, CACNA1H and ARMC5 This review describes the genes currently known to be responsible for primary aldosteronism, discusses the origin of aldosterone-producing adenomas and considers the future clinical implications based on these novel insights.

SFE/SFHTA/AFCE consensus on primary aldosteronism, part 5: Genetic diagnosis of primary aldosteronism

While the majority of cases of primary aldosteronism (PA) are sporadic, four forms of autosomal-dominant inheritance have been described: familial hyperaldosteronism (FH) types I to IV. FH-I, also called glucocorticoid-remediable aldosteronism, is characterized by early and severe hypertension, usually before the age of 20 years. It is due to the formation of a chimeric gene between the adjacent CYP11B2 and CYP11B1 genes (coding for aldosterone synthase and 11β-hydroxylase, respectively). FH-I is often associated with family history of stroke before 40years of age. FH-II is clinically and biochemically indistinguishable from sporadic forms of PA and is only diagnosed on the basis of two or more affected family members. No causal genes have been identified so far and no genetic test is available. FH-III is characterized by severe and early-onset hypertension in children and young adults, resistant to treatment and associated with severe hypokalemia. Mild forms, resembling FH-II, have been described. FH-III is due to gain-of-function mutations in the KCNJ5 gene. Recently, a new autosomal-dominant form of familial PA, FH-IV, associated with mutations in the CACNA1H gene, was described in patients with hypertension and PA before the age of 10years. In rare cases, PA may be associated with complex neurologic disorder involving epileptic seizures and cerebral palsy (Primary Aldosteronism, Seizures, and Neurologic Abnormalities [PASNA]) due to de novo germline CACNA1D mutations.

Inherited forms of mineralocorticoid hypertension

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.

Mineralocorticoid and apparent mineralocorticoid syndromes of secondary hypertension

The mineralocorticoid aldosterone is a key hormone in the regulation of plasma volume and blood pressure in man. Excessive levels of this mineralocorticoid have been shown to mediate metabolic disorders and end-organ damage more than what can be attributed to its effects on blood pressure alone. Inappropriate excess levels of aldosterone contribute significantly to the cardiorenal metabolic syndrome and target organ injury that include atherosclerosis, myocardial hypertrophy, fibrosis, heart failure, and kidney disease. The importance of understanding the role of excess mineralocorticoid hormones such as aldosterone in resistant hypertension and in those with secondary hypertension should be visited. Primary aldosteronism is one of the commonly identified causes of hypertension and is treatable and/or potentially curable. We intend to review the management of mineralocorticoid-induced hypertension in the adult population along with other disease entities that mimic primary aldosteronism.

An update on novel mechanisms of primary aldosteronism

Primary aldosteronism (PA) is the most common and curable form of secondary hypertension. It is caused in the majority of cases by either unilateral aldosterone overproduction due to an aldosterone-producing adenoma (APA) or by bilateral adrenal hyperplasia. Recent advances in genome technology have allowed researchers to unravel part of the genetic abnormalities underlying the development of APA and familial hyperaldosteronism. Recurrent somatic mutations in genes coding for ion channels (KCNJ5 and CACNA1D) and ATPases (ATP1A1 and ATP2B3) regulating intracellular ionic homeostasis and cell membrane potential have been identified in APA. Similar germline mutations of KCNJ5 were identified in a severe familial form of PA, familial hyperaldosteronism type 3 (FH3), whereas de novo germline CACNA1D mutations were found in two cases of hyperaldosteronism associated with a complex neurological disorder. These results have allowed a pathophysiological model of APA development to be established. This model involves modifications in intracellular ionic homeostasis and membrane potential, accounting for ∼50% of all tumors, associated with specific gender differences and severity of PA. In this review, we describe the different genetic abnormalities associated with PA and discuss the mechanisms whereby they lead to increased aldosterone production and cell proliferation. We also address some of the foreseeable consequences that genetic knowledge may contribute to improve diagnosis and patient care.

Genetics of mineralocorticoid excess: an update for clinicians

Aldosterone plays a major role in the regulation of sodium and potassium homeostasis and blood pressure. More recently, aldosterone has emerged as a key hormone mediating end organ damage. In extreme cases, dysregulated aldosterone production leads to primary aldosteronism (PA), the most common form of secondary hypertension. However, even within the physiological range, high levels of aldosterone are associated with an increased risk of developing hypertension over time. PA represents the most common and curable form of hypertension, with a prevalence that increases with the severity of hypertension. Although genetic causes underlying glucocorticoid-remediable aldosteronism, one of the three Mendelian forms of PA, were established some time ago, somatic and inherited mutations in the potassium channel GIRK4 have only recently been implicated in the formation of aldosterone-producing adenoma (APA) and in familial hyperaldosteronism type 3. Moreover, recent findings have shown somatic mutations in two additional genes, involved in maintaining intracellular ionic homeostasis and cell membrane potential, in a subset of APAs. This review summarizes our current knowledge on the genetic determinants that contribute to variations in plasma aldosterone and renin levels in the general population and the genetics of familial and sporadic PA. Various animal models that have significantly improved our understanding of the pathophysiology of excess aldosterone production are also discussed. Finally, we outline the cardiovascular, renal, and metabolic consequences of mineralocorticoid excess beyond blood pressure regulation.

Positive association between aldosterone-renin ratio and carotid intima-media thickness in hypertensive children

INTRODUCTION

From an early age, hypertension can damage blood vessels through multiple mechanisms. The aim of this study was to evaluate the presence of vascular damage and whether it is associated with the mineralo- and glucocorticoid profiles of hypertensive children.

SUBJECTS AND METHODS

We studied 64 hypertensive children. Anthropometric parameters and serum aldosterone (SA), plasma renin activity (PRA), aldosterone/renin ratio (ARR), cortisol (F) and cortisone (E) were measured. The serum F/E ratio was calculated to estimate the activity of the enzyme 11β-HSD2. Vascular damage was determined by carotid intima-media thickness (cIMT) and flow-mediated dilation of the brachial artery (FMD) on ultrasound.

RESULTS

(median; Q1-Q3) Of the patients observed, 39% were females, and the median value for age (years) was 11.2 (9.1-13.3), for BMI (SDS) was 1.36 (0.84-1.80), for body fat mass (%) was 28.3 (17.8-36.0), for SBP index was 1.17 (1.12-1.25) and for the DBP index was 1.27 (1.16-1.36). Measurements revealed an SA level higher than 491 pmol/l in 4/64 patients, a PRA value lower than 0.5 ng/ml/h in 2/64, an ARR higher than 10 in 3/64 and serum F/E ratio higher than 4.3 in 10/64. The median brachial FMD (%) was 8.41 (5.61-10.91), and the median cIMT (mm) was 0.40 (0.37-0.43). The ARR was the only variable that explained changes in cIMT (β = 0.571, R(2 ) = 0.315, P < 0.0001).

CONCLUSION

Our results showed a positive association between cIMT and the ARR, suggesting an important role of the renin-aldosterone axis in the regulation of early vascular damage in hypertensive children.

Role of KCNJ5 in familial and sporadic primary aldosteronism

Primary aldosteronism is characterised by the dysregulation of aldosterone production and comprises both sporadic forms, caused by an aldosterone-producing adenoma or bilateral adrenal hyperplasia, and familial forms (familial hyperaldosteronism types I, II and III). The two principal physiological regulators of aldosterone synthesis are angiotensin II and serum K(+), which reverse the high resting K(+) conductance and hyperpolarized membrane potential of adrenal glomerulosa cells. The resulting membrane depolarization causes the opening of voltage-gated Ca(2+) channels and an increase in intracellular Ca(2+) that stimulates aldosterone biosynthesis. Point mutations in the KCNJ5 gene, which encodes the G-protein-activated inward rectifier K(+) channel 4 (GIRK4), have been implicated in the pathogenesis of both sporadic and familial forms of primary aldosteronism. These mutations interfere with the selectivity filter of GIRK4 causing Na(+) entry, cell depolarization and Ca(2+) channel opening, resulting in constitutive aldosterone production. Seven families with familial hyperaldosteronism caused by KCNJ5 germline mutations have so far been described, and multicentre studies have reported KCNJ5 mutations in approximately 40% of sporadic aldosterone-producing adenomas. Herein, we review the role of GIRK4 in adrenal pathophysiology and provide an overview of the clinical and biochemical phenotypes resulting from KCNJ5 mutations in patients with sporadic and familial primary aldosteronism.

Management of blood pressure in children

PURPOSE OF REVIEW

This review summarizes recent insights into the epidemiology of primary hypertension in children, with emphasis on the most important risk factors for the development of hypertension, and also updates current options for treating primary hypertension in children.

RECENT FINDINGS

There is growing evidence that the prevalence of hypertension has increased over the past decade and that the epidemic of obesity has played a key role in the increase of blood pressure (BP) in the USA and abroad. Recent studies have shown that in addition to obesity, environmental factors such as second-hand smoking and sedentary lifestyle are important in development of hypertension even in preschool age children. Studies also have confirmed the effect of vegetables and fruits on lowering BP. Recent clinical trials of valsartan and olmesartan have provided efficacy and safety information for use in children.

SUMMARY

The increased prevalence of hypertension in children in recent years emphasizes the need for a more aggressive approach to screen and diagnose elevated BP even in early childhood. Early initiation of treatment is important to decrease the risk of cardiovascular morbidity in adulthood.

A New Presentation of the Chimeric CYP11B1/CYP11B2 Gene With Low Prevalence of Primary Aldosteronism and Atypical Gene Segregation Pattern

Familial hyperaldosteronism type I is caused by an unequal crossover of 11β-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2) genes, giving rise to a chimeric CYP11B1/CYP11B2 gene (CG). We describe a family carrying a CG with high levels of free 18-hydroxycortisol but low prevalence of primary aldosteronism (PA) and an atypical CG inheritance pattern in a family of 4 generations with 16 adults and 13 children, we measured the arterial blood pressure, serum aldosterone, and plasma renin activity and then calculated the serum aldosterone:plasma renin activity ratio and urinary free 18-hydroxycortisol. We identified the CG by long-extension PCR and predicted its inheritance pattern. The CG was found in 24 of 29 subjects (10 children and 14 adults). In CG+ patients, hypertension and high 18-hydroxycortisol were prevalent (83% and 100%, respectively). High serum aldosterone:plasma renin activity ratio was more frequent in pediatric than adult patients (80% versus 36%; P <0.001). An inverse association between serum aldosterone:plasma renin activity ratio and age was observed ( r =−0.48; P =0.018). Sequence analysis identified the CYP11B1/CYP11B2 crossover in a 50-bp region spanning intron 3 of CYP11B1 and exon 4 of CYP11B2. The CG segregation differs from an autosomal disease, showing 100% of CG penetrance in generations II and III. Statistical analysis suggests that inheritance pattern was not attributed to random segregation ( P <0.001). In conclusion, we describe a family with an atypical CYP11B1/CYP11B2 gene inheritance pattern and variable phenotypic expression, where the majority of pediatric patients have primary aldosteronism. Most adults have normal aldosterone and renin levels, which could mask them as essential hypertensives.

Prevalence and Characteristics of Familial Hyperaldosteronism

Primary aldosteronism (PA) is the most frequent cause of secondary hypertension, and patients display an increased prevalence of cardiovascular events compared with essential hypertensives. To date, 3 familial forms of PA have been described and termed familial hyperaldosteronism types I, II, and III (FH-I to -III). The aim of this study was to investigate the prevalence and clinical characteristics of the 3 forms of FH in a large population of PA patients. Three-hundred consecutive PA patients diagnosed in our unit were tested by long-PCR of the CYP11B1/CYP11B2 hybrid gene that causes FH-I, and all of the available relatives of PA patients were screened to confirm or exclude PA and, thus, FH-II. Urinary 18-hydroxycortisol and 18-oxocortisol were measured in all of the familial PA patients. Two patients were diagnosed with FH-I (prevalence: 0.66%), as well as 21 of their relatives, and clinical phenotypes of the 2 affected families varied markedly. After exclusion of families who refused testing and those who were not informative, 199 families were investigated, of which 12 were diagnosed with FH-II (6%) and an additional 15 individuals had confirmed PA; clinical and biochemical phenotypes of FH-II families were not significantly different from sporadic PA patients. None of the families displayed a phenotype compatible with FH-III diagnosis. Our study demonstrates that familial forms of hyperaldosteronism are more frequent than previously expected and reinforces the recommendation of the Endocrine Society Guidelines to screen all first-degree hypertensive relatives of PA patients.