Abstract P180: Proximity To Telomeres Or A+t Content Suffices To Project Monogenic Hypertension At An 80 % Matching Rate

Hypertension remains the single biggest risk factor contributing to the global burden of disease and mortality. Despite the prevalence of individuals with elevated blood pressure, the role of genetics in hypertension is poorly understood. We have recently demonstrated that mutations causative to the congenital disorder can be projected by a stochastic approach centered on chromosomal characteristics of proximity to telomeres (F(i)) and adenine and thymine (A+T) content (F(ii)). Here, we investigated the two chromosomal factors, F(i) and F(ii), to determine whether they are associated with high mutation rates in human genes related to essential and monogenic hypertension (MH). In essential hypertension, the mismatch of two factors and the disease as well as the correlation between the full-length size of the genes and A+T content was either unexpectedly low (~53%) or statistically insignificant. When we examined 79 genes susceptible to MH and contributing to the genetic architecture of hypertension focusing on the factor-disease matching rate, 64 of 79 genes exclusively satisfied either the F(i) or F(ii) condition. Unlike the previous study on essential hypertension, a quarter of these genes displayed high A+T content at higher than 59%. 16% of genes (13 of 79) associated with hypertension met neither F(i) nor F(ii). Furthermore, 2 of 79 genes met both F(i) and F(ii). Our analysis suggests that these two factors can explain the cause of genetic mutations in 79 loci proposed in MH roughly at an 80% rate. In comparison, these two factors proposed can only explain the cause of idiopathic disease such as essential hypertension at a rate comparable to flipping a coin (50 %). The proposed genomic analyses demonstrate an intermediate matching rate or a mediocre predictability (~75% or less) between the cause of genetic mutations and the disease in the cases of congenital heart disease, thoracic aortic aneurysm, and age-related degenerative disorder.

Unravelling the tangled web of hypertension and cancer

Cardiovascular disease remains the primary cause of mortality globally, being responsible for an estimated 17 million deaths every year. Cancer is the second leading cause of death on a global level with roughly 9 million deaths per year being attributed to neoplasms. The two share multiple common risk factors such as obesity, poor physical exercise, older age, smoking and there exists rare monogenic hypertension syndromes. Hypertension is the most important risk factor for cardiovascular disease and affects more than a billion people worldwide and may also be a risk factor for the development of certain types of cancer (e.g. renal cell carcinoma (RCC)). The interaction space of the two conditions becomes more complicated when the well-described hypertensive effect of certain antineoplastic drugs is considered along with the extensive amount of literature on the association of different classes of antihypertensive drugs with cancer risk/prevention. The cardiovascular risks associated with antineoplastic treatment calls for efficient management of relative adverse events and the development of practical strategies for efficient decision-making in the clinic. Pharmacogenetic interactions between cancer treatment and hypertension-related genes is not to be ruled out, but the evidence is not still ample to be incorporated in clinical practice. Precision Medicine has the potential to bridge the gap of knowledge regarding the full spectrum of interactions between cancer and hypertension (and cardiovascular disease) and provide novel solutions through the emerging field of cardio-oncology. In this review, we aimed to examine the bidirectional associations between cancer and hypertension including pharmacotherapy.

Factors Associated with Mutations: Their Matching Rates to Cardiovascular and Neurological Diseases

Monogenic hypertension is rare and caused by genetic mutations, but whether factors associated with mutations are disease-specific remains uncertain. Given two factors associated with high mutation rates, we tested how many previously known genes match with (i) proximity to telomeres or (ii) high adenine and thymine content in cardiovascular diseases (CVDs) related to vascular stiffening. We extracted genomic information using a genome data viewer. In human chromosomes, 64 of 79 genetic loci involving >25 rare mutations and single nucleotide polymorphisms satisfied (i) or (ii), resulting in an 81% matching rate. However, this high matching rate was no longer observed as we checked the two factors in genes associated with essential hypertension (EH), thoracic aortic aneurysm (TAA), and congenital heart disease (CHD), resulting in matching rates of 53%, 70%, and 75%, respectively. A matching of telomere proximity or high adenine and thymine content projects the list of loci involving rare mutations of monogenic hypertension better than those of other CVDs, likely due to adoption of rigorous criteria for true-positive signals. Our data suggest that the factor–disease matching rate is an accurate tool that can explain deleterious mutations of monogenic hypertension at a >80% match—unlike the relatively lower matching rates found in human genes of EH, TAA, CHD, and familial Parkinson’s disease.

Monogenic causes of secondary hypertension (lecture)

In recent decades, some monogenic forms of arterial hypertension have been identified. They were caused by specific pathways due to rare disruptive mutations in individual genes that determined an early and severe hypertension phenotype. At least 37 genes are known, the disruption of which is clearly accompanied by a dysfunction of the blood pressure regulation. This knowledge improves our understanding of both the mechanisms of development and treatment of hypertension. The genetic causes of secondary hypertension are usually due to a single gene disorder. The discovery of genes responsible for monogenic forms of hypertension revealed the role of the kidneys and adrenal glands as important players in the regulation of blood pressure. Most of these syndromes are caused by mutations that lead to increased of the function or its loss, which in turn leads to changes in the content of mineralocorticoids, glucocorticoids or sympathetic pathway activation. Monogenic forms of hypertension often lead to severe forms of hypertension, electrolyte and hormonal disorders, accompanied by drug resistance, and often cause a higher risk of cardiovascular events and premature death. The lecture provides recommendations for genetic testing in hypertension, an algorithm for diagnostic examination of a patient with suspected monogenic form of hypertension, as well as features of the clinical course and treatment of the main known forms of monogenic hypertension.

Overview of Monogenic Forms of Hypertension Combined With Hypokalemia

Hypertension is an important risk factor in many conditions and creates a heavy burden of disease and mortality globally. Polygenic hypertension is the most common form; however, it is increasingly recognized that monogenic hypertension is not rare, especially in patients with electrolyte disorders. Single genetic alterations are associated with plasma volume expansion and catecholamines/sympathetic excess with simultaneously increased potassium excretion in the urine and potassium intracellular shift. Early-onset refractory hypertension and profound hypokalemia are characteristics of monogenic hypertension. However, accumulated evidence shows the existence of phenotypic heterogeneity in monogenic hypertension meaning that, even for mild symptoms, clinicians cannot easily exclude the possibility of monogenic hypertension. Genetic, epigenetic and non-genetic factors are all possible mechanisms influencing phenotypic diversity. Genetic sequencing is a precise and efficient method that can broaden the mutant gene spectrum of the disease and is very helpful for understanding the pathophysiology of monogenic hypertension. Genetic sequencing, along with biochemical tests and imaging modalities, is essential for the early diagnosis and targeted management of monogenic hypertension to avoid long-term catastrophic complications.

Genetic screening for monogenic hypertension in hypertensive individuals in a clinical setting

BackgroundMonogenic hypertension describe a series of hypertensive syndromes that are inherited by Mendelian laws. Sometimes genetic testing is required to provide evidence for their diagnoses, precise classification and targeted treatment. This study is the first to investigate the clinical utility of a causative gene screening and the combined yield of gene product expression analyses in cases with suspected monogenic hypertension.MethodsWe performed a large-scale multi-centre clinical genetic research of 1179 expertly selected hypertensive individuals from the Chinese Han population. Targeted sequencing were performed to evaluate 37 causative genes of potential cases of monogenic hypertension. Pathogenic and likely pathogenic variants were classified using the American College of Medical Genetics guidelines. Additionally, 49 variants of unknown significance (VUS) that had relatively high pathogenicity were selected and analysed using immunoblot protein expression assays.Results21 pathogenic or likely pathogenic variants were identified in 33 of 1179 cases (2.80%). Gene product expression analyses showed 27 VUSs harboured by 49 individuals (4.16%) could lead to abnormally expressed protein levels. Consequently, combining genetic screening with gene product expression analyses increased the diagnostic yield from 2.80% to 6.79%. The main aetiologies established were primary aldosteronism (PA; 27, 2.29%) and pheochromocytoma and paraganglioma (PPGL; 10, 0.85%).ConclusionMolecular diagnoses obtained using causative gene screening combined with gene product expression analyses initially achieved a modest diagnostic yield. Our data highlight the predominant roles of PA and PPGL. Furthermore, we provide evidence indicating the enhanced diagnostic ability of combined genetic and functional evaluation.

Premature Stroke Secondary to Severe Hypertension Results from Liddle Syndrome Caused by a Novel SCNN1B Mutation

Introduction: Liddle syndrome (LS), an autosomal dominant and inherited monogenic hypertension syndrome caused by pathogenic mutations in the epithelial sodium channel (ENaC) genes SCNN1A, SCNN1B, and SCNN1G. Objective: This study was designed to identify a novel SCNN1B missense mutation in a Chinese family with a history of stroke, and to confirm that the identified mutation is responsible for LS in this family. Methods: DNA samples were collected from the proband and 11 additional relatives. Next-generation sequencing was performed in the proband to find candidate variants. In order to exclude genetic polymorphism, the candidate variantin SCNN1B was verified in other family members, 100 hypertensives, and 100 healthy controls by Sanger sequencing. Results: Genetic testing revealeda novel and rare heterozygous variant in SCNN1B in the proband. This variant resulted in a substitution of threonine instead of proline at codon 617, altering the PY motif of β-ENaC. The identified mutation was only verified in 5 relatives. In silico analyses indicated that this variant was highly pathogenic. In this family, phenotypic heterogeneity was present among 6 LS patients. Tailored medicine with amiloride was effective in controlling hypertension and improving the serum potassium concentration in patients with LS. Conclusions:We identified a novel SCNN1B mutation (c.1849C>A) in a family affected by LS. Patients with LS, especially those with severe hypertension, should be alert for the occurrence of premature stroke. Timely diagnosis using genetic testing and tailored treatment with amiloride can help LS patients to avoid severe complications.

Gene big data- A Research for Monogenic Hypertension Diagnosis

This paper designed a detailed procedure for monogenic hypertension diagnosis by Whole Exome Sequencing (WES) and provided reliable precise medication guidance. Identification of mutated points provides the clinician valuable information for effective individualized therapeutic option. Therapeutic options that specifically restore the pathway disturbed by these point mutations can be selected to give a precise medicinal guidance.