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BACKGROUND Genome-wide association studies have identified single nucleotide polymorphisms (SNPs) near the uromodulin gene (UMOD) affecting uromodulin excretion and blood pressure (BP). Uromodulin is almost exclusively expressed in the thick ascending limb (TAL) of the loop of Henle and its effect on BP appears to be mediated via the TAL sodium transporter, NKCC2. Loop-diuretics block NKCC2 but are not commonly used in hypertension management. Volume overload is one of the primary drivers for uncontrolled hypertension, so targeting loop-diuretics to individuals who are more likely to respond to this drug class, using the UMOD genotype, could be an efficient precision medicine strategy. METHODS The BHF UMOD Trial is a genotype-blinded, multicenter trial comparing BP response to torasemide between individuals possessing the AA genotype of the SNP rs13333226 and those possessing the G allele. 240 participants (≥18 years) with uncontrolled BP, on ≥1 antihypertensive agent for ≥3 months, will receive treatment with Torasemide, 5 mg daily for 16 weeks. Uncontrolled BP is average home systolic BP (SBP) >135 mmHg and/or diastolic BP >85 mmHg. The primary outcome is the change in 24-hour ambulatory SBP area under the curve between baseline and end of treatment. Sample size was calculated to detect a 4 mmHg difference between groups at 90% power. Approval by West of Scotland Research Ethics Committee 5 (16/WS/0160). RESULTS The study should conclude August 2021. CONCLUSIONS If our hypothesis is confirmed, a genotype-based treatment strategy for loop diuretics would help reduce the burden of uncontrolled hypertension. CLINICAL TRIALS REGISTRATION https://clinicaltrials.gov/ct2/show/NCT03354897., Graphical Abstract Graphical Abstract

A complex network of interacting pathways involving renal, neural, endocrine, vascular and other mechanisms controls the main determinants of blood pressure - cardiac output and total peripheral resistance. Multiple genes within each of these systems contribute to the specialized functions regulating blood pressure. The monogenic forms of blood pressure dysregulation have provided valuable insights into blood pressure regulation and expanded our understanding of both the mechanisms and the treatment of hypertension. Genome wide association studies have identified over 100 single nucleotide polymorphisms associated with blood pressure phenotypes and have identified plausible novel pathways of BP regulation and putative drug targets.

Hypertension and heart failure are leading causes of death and disability worldwide. Both are complex multifactorial conditions with hypertension and heart failure at either ends of the cardiovascular continuum. Rare mutations resulting in monogenic forms of hypertension, hypotension and cardiomyopathies highlight the importance of genetics in disease causation and consequent implications for disease prediction and treatment. Advances in genomics have accelerated over the last decade leading to an unparalleled leap in our understanding of the genetic architecture of both hypertension and heart failure. In this chapter, we describe the current state of the art in the genetics of both conditions, hypertension and heart failure, focussing on biologic pathways that are perturbed and opportunities for early detection and treatment.