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Backgrounds: While many studies agree that consanguinity increases the rate of congenital heart disease (CHD), few genome analyses have been conducted with consanguineous CHD cohorts. Methods: We recruited 73 CHD probands from consanguineous families in Turkey and used whole‐exome sequencing (WES) to identify genetic lesions in these patients. Results: On average, each patient had 6.95 rare damaging homozygous variants, 0.68 of which are loss‐of‐function (LoF) variants. Seven patients (9.6%) carried damaging homozygous variants in five causal CHD genes. Six of those patients exhibited laterality defects (six HTX and one D‐TGA). Three additional patients (4.1%) harbored other types of CHD‐associated genomic alterations, which overall explained 13.7% (10/73) of the cohort. The contribution from recessive variants in our cohort is higher than 1.8% reported from a cohort of 2871 CHD subjects where 5.6% of subjects met the criteria for consanguinity. Conclusions: Our WES screen of a Turkish consanguineous population with structural CHD revealed its unique genetic architecture. Six of seven damaging homozygous variants in CHD causal genes occur in the setting of laterality defects implies a strong contribution from consanguinity to these defects specifically. Our study thus provided valuable information about the genetic landscape of CHD in consanguineous families in Turkey. [ABSTRACT FROM AUTHOR]

Objective: Unusual clinical course. Background: Bartter syndrome is a rare genetic disease characterized by hypokalemia, metabolic alkalosis, and hyperreninemic hyperaldosteronism. Five different subtypes have been described based on the genetic defect identified. Bartter syndrome type II is caused by homozygous or compound heterozygous loss-of-function mutations in the KCNJ1 gene encoding ROMK. This subtype is typically described as a severe antenatal form of the disease, often presenting with polyhydramnios before childbirth. Case Report: Here, we describe the case of a 26-year-old man who presented with generalized body weakness and hypokalemia and was ultimately diagnosed with Bartter syndrome type II based on his clinical features coupled with the identification of a homozygous missense mutation in KCNJ1. Conclusions: To the best of our knowledge, this is the fifth case of late-onset Bartter syndrome type II. Interestingly, the mutation identified in our patient has been previously described in patients with antenatal Bartter's Syndrome. The late presentation in our patient suggests a surprising degree of phenotypic variability, even in patients carrying the identical disease-causing mutation. [ABSTRACT FROM AUTHOR]

Calcineurin is a calcium/calmodulin-regulated phosphatase known for its role in activation of T cells following engagement of the T cell receptor. Calcineurin inhibitors (CNIs) are widely used as immunosuppressive agents; common adverse effects of CNIs are hypertension and hyperkalemia. While previous studies have implicated activation of the Na-Cl cotransporter (NCC) in the renal distal convoluted tubule (DCT) in this toxicity, the molecular mechanism of this effect is unknown. The renal effects of CNIs mimic the hypertension and hyperkalemia that result from germ-line mutations in with-no-lysine (WNK) kinases and the Kelch-like 3 (KLHL3)- CUL3 ubiquitin ligase complex. WNK4 is an activator of NCC and is degraded by binding to KLHL3 followed by WNK4's ubiquitylation and proteasomal degradation. This binding is prevented by phosphorylation of KLHL3 at serine 433 (KLHL3S433-P) via protein kinase C, resulting in increased WNK4 levels and increased NCC activity. Mechanisms mediating KLHL3S433-P dephosphorylation have heretofore been unknown. We now demonstrate that calcineurin expressed in DCT is a potent KLHL3S433-P phosphatase. In mammalian cells, the calcium ionophore ionomycin, a calcineurin activator, reduces KLHL3S433-P levels, and this effect is reversed by the calcineurin inhibitor tacrolimus and by siRNA-mediated knockdown of calcineurin. In vivo, tacrolimus increases levels of KLHL3S433-P, resulting in increased levels of WNK4, phosphorylated SPAK, and NCC. Moreover, tacrolimus attenuates KLHL3- mediated WNK4 ubiquitylation and degradation, while this effect is absent in KLHL3 with S433A substitution. Additionally, increased extracellular K+ induced calcineurin-dependent dephosphorylation of KLHL3S433-P. These findings demonstrate that KLHL3S433-P is a calcineurin substrate and implicate increased KLHL3 phosphorylation in tacrolimus-induced pathologies. [ABSTRACT FROM AUTHOR]

Non-syndromic craniosynostosis (NSC) is a frequent congenital malformation in which one or more cranial sutures fuse prematurely. Mutations causing rare syndromic craniosynostoses in humans and engineered mouse models commonly increase signaling of the Wnt, bone morphogenetic protein (BMP), or Ras/ERK pathways, converging on shared nuclear targets that promote bone formation. In contrast, the genetics of NSC is largely unexplored. More than 95% of NSC is sporadic, suggesting a role for de novo mutations. Exome sequencing of 291 parent-offspring trios with midline NSC revealed 15 probands with heterozygous damaging de novo mutations in 12 negative regulators of Wnt, BMP, and Ras/ERK signaling (10.9-fold enrichment, P = 2.4 x 10-11). SMAD6 had 4 de novo and 14 transmitted mutations; no other gene had more than 1. Four familial NSC kindreds had mutations in genes previously implicated in syndromic disease. Collectively, these mutations contribute to 10% of probands. Mutations are predominantly loss-of-function, implicating haploinsufficiency as a frequent mechanism. A common risk variant near BMP2 increased the penetrance of SMAD6 mutations and was overtransmitted to patients with de novo mutations in other genes in these pathways, supporting a frequent two-locus pathogenesis. These findings implicate new genes in NSC and demonstrate related pathophysiology of common non-syndromic and rare syndromic craniosynostoses. These findings have implications for diagnosis, risk of recurrence, and risk of adverse neurodevelopmental outcomes. Finally, the use of pathways identified in rare syndromic disease to find genes accounting for non-syndromic cases may prove broadly relevant to understanding other congenital disorders featuring high locus heterogeneity. [ABSTRACT FROM AUTHOR]

Many aspects of the evolutionary process of tumorigenesis that are fundamental to cancer biology and targeted treatment have been challenging to reveal, such as the divergence times and genetic clonality of metastatic lineages. To address these challenges, we performed tumor phylogenetics using molecular evolutionary models, reconstructed ancestral states of somatic mutations, and inferred cancer chronograms to yield three conclusions. First, in contrast to a linear model of cancer progression, metastases can originate from divergent lineages within primary tumors. Evolved genetic changes in cancer lineages likely affect only the proclivity toward metastasis. Single genetic changes are unlikely to be necessary or sufficient for metastasis. Second, metastatic lineages can arise early in tumor development, sometimes long before diagnosis. The early genetic divergence of some metastatic lineages directs attention toward research on driver genes that are mutated early in cancer evolution. Last, the temporal order of occurrence of driver mutations can be inferred from phylogenetic analysis of cancer chronograms, guiding development of targeted therapeutics effective against primary tumors and metastases. [ABSTRACT FROM AUTHOR]

Background Bidirectional intraflagellar transport (IFT) consists of two major protein complexes, IFT-A and IFT-B. In contrast to the IFT-B complex, all components of IFT-A have recently been linked to human ciliopathies when defective. We therefore hypothesised that mutations in additional IFT-B encoding genes can be found in patients with multisystemic ciliopathies. Methods We screened 1628 individuals with renoocular ciliopathies by targeted next-generation sequencing of ciliary candidate genes, including all IFT-B encoding genes. Results Consequently, we identified a homozygous mutation in IFT81 affecting an obligatory donor splice site in an individual with nephronophthisis and polydactyly. Further, we detected a loss-of-stop mutation with extension of the deduced protein by 10 amino acids in an individual with neuronal ceroid lipofuscinosis-1. This proband presented with retinal dystrophy and brain lesions including cerebellar atrophy, a phenotype to which the IFT81 variant might contribute. Cultured fibroblasts of this latter affected individual showed a significant decrease in ciliated cell abundance compared with controls and increased expression of the transcription factor GLI2 suggesting deranged sonic hedgehog signalling. Conclusions This work describes identification of mutations of IFT81 in individuals with symptoms consistent with the clinical spectrum of ciliopathies. It might represent the rare case of a core IFT-B complex protein found associated with human disease. Our data further suggest that defects in the IFT-B core are an exceedingly rare finding, probably due to its indispensable role for ciliary assembly in development. [ABSTRACT FROM AUTHOR]

Upon detection of pathogen-associated molecular patterns, innate immune receptors initiate inflammatory responses. These receptors include cytoplasmic NOD-like receptors (NLRs) whose stimulation recruits and proteolytically activates caspase-1 within the inflammasome, a multiprotein complex. Caspase-1 mediates the production of interleukin-1 family cytokines (IL1FCs), leading to fever and inflammatory cell death (pyroptosis). Mutations that constitutively activate these pathways underlie several autoinflammatory diseases with diverse clinical features. We describe a family with a previously unreported syndrome featuring neonatal-onset enterocolitis, periodic fever, and fatal or near-fatal episodes of autoinflammation. We show that the disease is caused by a de novo gain-of-function mutation in NLRC4 encoding a p.Val341Ala substitution in the HD1 domain of the protein that cosegregates with disease. Mutant NLRC4 causes constitutive IL1FC production and macrophage cell death. Infected macrophages from affected individuals are polarized toward pyroptosis and exhibit abnormal staining for inflammasome components. These findings identify and describe the cause of a life-threatening but treatable autoinflammatory disease that underscores the divergent roles of the NLRC4 inflammasome. [ABSTRACT FROM AUTHOR]

Background Whole-exome sequencing studies in autism spectrum disorder (ASD) have identified de novo mutations in novel candidate genes, including the synaptic gene Eighty-five Requiring 3A (EFR3A). EFR3A is a critical component of a protein complex required for the synthesis of the phosphoinositide PtdIns4P, which has a variety of functions at the neural synapse. We hypothesized that deleterious mutations in EFR3A would be significantly associated with ASD. Methods We conducted a large case/control association study by deep resequencing and analysis of whole-exome data for coding and splice site variants in EFR3A. We determined the potential impact of these variants on protein structure and function by a variety of conservation measures and analysis of the Saccharomyces cerevisiae Efr3 crystal structure. We also analyzed the expression pattern of EFR3A in human brain tissue. Results Rare nonsynonymous mutations in EFR3A were more common among cases (16 / 2,196 = 0.73%) than matched controls (12 / 3,389 = 0.35%) and were statistically more common at conserved nucleotides based on an experiment-wide significance threshold (P = 0.0077, permutation test). Crystal structure analysis revealed that mutations likely to be deleterious were also statistically more common in cases than controls (P = 0.017, Fisher exact test). Furthermore, EFR3A is expressed in cortical neurons, including pyramidal neurons, during human fetal brain development in a pattern consistent with ASD-related genes, and it is strongly co-expressed (P < 2.2 × 10-16, Wilcoxon test) with a module of genes significantly associated with ASD. Conclusions Rare deleterious mutations in EFR3A were found to be associated with ASD using an experiment-wide significance threshold. Synaptic phosphoinositide metabolism was strongly implicated in syndromic forms of ASD. These data for EFR3A strengthen the evidence for the involvement of this pathway in idiopathic autism. [ABSTRACT FROM AUTHOR]

Pseudohypoaldosteronism type II (PHAII) is a rare Mendelian syndrome featuring hypertension and hyperkalemia resulting from constitutive renal salt reabsorption and impaired K+ secretion. Recently, mutations in Kelch-like 3 (KLHL3) and Cullin 3 (CUL3), components of an E3 ubiquitin ligase complex, were found to cause PHAII, suggesting that loss of this complex's ability to target specific substrates for ubiquitination leads to PHAII. By MS and coimmunoprecipitation, we show that KLHL3 normally binds to WNK1 and WNK4, members of WNK (with no lysine) kinase family that have previously been found mutated in PHAII. We show that this binding leads to ubiquitination, including polyubiquitination, of at least 15 specific sites in WNK4, resulting in reduced WNK4 levels. Dominant disease-causing mutations in KLHL3 and WNK4 both impair WNK4 binding, ubiquitination, and degradation. WNK4 normally induces clearance of the renal outer medullary K+ channel (ROMK) from the cell surface. We show that WT but not mutant KLHL3 inhibits WNK4-induced reduction of ROMK level. We show that PHAII-causing mutations in WNK4 lead to a marked increase in WNK4 protein levels in the kidney in vivo. These findings demonstrate that CUL3- RING (really interesting new gene) ligases that contain KLHL3 target ubiquitination of WNK4 and thereby regulate WNK4 levels, which in turn regulate levels of ROMK. These findings reveal a specific role of CUL3 and KLHL3 in electrolyte homeostasis and provide a molecular explanation for the effects of disease-causing mutations in both KLHL3 and WNK4. [ABSTRACT FROM AUTHOR]

αβ T-cell repertoire selection is mediated by peptide-MHC complexes presented by thymic epithelial or myeloid cells, and by lipid-CD1 complexes expressed by thymocytes. γd T-cell repertoire selection, by contrast, is largely unresolved. Mice mutant for Skint-1, a unique Ig superfamily gene, do not develop canonical Vγ5Vd1+ dendritic epidermal T cells. This study shows that transgenic Skint-1, across a broad range of expression levels, precisely and selectively determines the Vγ5Vd1+ dendritic epidermal T-cell compartment. Skint-1 is expressed by medullary thymic epithelial cells, and unlike lipid-CD1 complexes, must be expressed by stromal cells to function efficiently. Its unusual transmembrane-cytoplasmic regions severely limit cell surface expression, yet increasing this or, conversely, retaining Skint1 intracellularly markedly compromises function. Each Skint1 domain appears nonredundant, including a unique decamer specifying IgV-domain processing. This investigation of Skint-1 biology points to complex events underpinning the positive selection of an intraepithelial γd repertoire. [ABSTRACT FROM AUTHOR]

The article discusses the study on the absence of (K)-specific methyltransferase 2D (MNT2D) gene mutations in abdominal paraganglioma (PGL). The study reportedly involved several PGLs from Karolinska University Hospital in Stockholm, Sweden. The results revealed that KMT2D mutations are not prevalent in abdominal paraganglioma.

Protein coding genes constitute only approximately 1% of the human genome but harbor 85% of the mutations with large effects on disease-related traits. Therefore, efficient strategies for selectively sequencing complete coding regions (i.e., "whole exome") have the potential to contribute to the understanding of rare and common human diseases. Here we report a method for whole-exome sequencing coupling Roche/NimbleGen whole exome arrays to the Illumina DNA sequencing platform. We demonstrate the ability to capture approximately 95% of the targeted coding sequences with high sensitivity and specificity for detection of homozygous and heterozygous variants. We illustrate the utility of this approach by making an unanticipated genetic diagnosis of congenital chloride diarrhea in a patient referred with a suspected diagnosis of Bartter syndrome, a renal salt-wasting disease. The molecular diagnosis was based on the finding of a homozygous missense D652N mutation at a position in 5LC26A3 (the known congenital chloride diarrhea locus) that is virtually completely conserved in orthologues and paralogues from invertebrates to humans, and clinical follow-up confirmed the diagnosis. To our knowledge, whole-exome (or genome) sequencing has not previously been used to make a genetic diagnosis. Five additional patients suspected to have Bartter syndrome but who did not have mutations in known genes for this disease had homozygous deleterious mutations in SLC26A3. These results demonstrate the clinical utility of whole-exome sequencing and have implications for disease gene discovery and clinical diagnosis. [ABSTRACT FROM AUTHOR]

WNK4 (with no lysine kinase 4) inhibits ROMK channel activity in the distal nephron by stimulating clathrin-dependent endocytosis, an effect attenuated by SGK1 (serum-glucocorticoids-induced kinase)-mediated phosphorylation. It has been suggested that increased ROMK activity because of SGK1-mediated inhibition of WNK4 plays a role in promoting renal K secretion in response to elevated serum K or high K (HK) intake. In contrast, intravascular volume depletion also increases SGK1 activity but fails to stimulate ROMK channels and K secretion. Because HK intake decreases Src family protein tyrosine kinase (PTK) activity an inhibitor of ROMK channels, it is possible that Src family PTK may modulate the effects of SGK1 on WNK4. Here, we show that c-Src prevents SGK1 from attenuating WNK4's inhibition of ROMK activity. This effect of c-Src was WNK4-dependent because c-Src had no effect on ROMK harboring mutation at the site of c-Src phosphorylation (R1Y337A) in the absence of WNK4. Moreover, expression c-Src diminished the SGK1-mediated increase in serine phosphorylation of WNK4, suggesting that c-Src enhances WNK4-mediated inhibition of ROMK channels by suppressing the SGK1-induced phosphorylation. This notion is also supported by the observation that c-Src was not able to modulate the interaction between SGK1 and WNK4 mutants (WNK4S1169A or WNK4S1169D) in which an SGK1-phosphorylation site (serine 1169) was mutated by alanine or aspartate. We conclude that c-Src inhibits SGK1-mediated phosphorylation hereby restoring the WNK4-mediated inhibition of ROMK channels thus suppressing K secretion. [ABSTRACT FROM AUTHOR]

Mutations in the kinase WNK4 cause pseudohypoaldosteronism type II (PHAII), a syndrome featuring hypertension and high serum K[sup+] levels (hyperkalemia). WNK4 has distinct functional states that regulate the balance between renal salt reabsorption and K[sup+] secretion by modulating the activities of renal transporters and channels, including the Na-Cl cotransporter NCC and the K[sup+] chan- nel ROMK. WNK4's functions could enable differential responses to intravascular volume depletion (hypovolemia) and hyperkalemia. Because hypovolemia is uniquely associated with high angiotensin II (Angli) levels. AnglI signaling might modulate WNK4 activity. We show that AnglI signaling in Xenopus oocytes increases NCC activity by abrogating WNK4's inhibition of NCC but does not alter WNK4's inhibition of ROMK. This effect requires AnglI, its receptor AT1R, and WNK4, and is prevented by the AT1R inhibitor losartan. NCC activity is also increased by WNK4 harboring mutations found in PHAII, and this activity cannot be further augmented by Angil signaling, consistent with PHAII mutations providing constitutive activation of the signaling pathway between AT1R and NCC. Angil's effect on NCC is also dependent on the kinase SPAK because dominant-negative SPAK or elimination of the SPAK binding motif in NCC prevent activation of NCC by Angll signaling. These effects extend to mammalian cells. AnglI increases phosphorylation of specific sites on SPAK and NCC that are necessary for activation of each in mpkDCT cells. These findings place WNK4 in the signaling pathway between AnglI and NCC. and provide a mechanism by which hypovolemia maximizes renal salt reabsoprtion without concomitantly increasing K secretion. [ABSTRACT FROM AUTHOR]

The effects of alleles in many genes are believed to contribute to common complex diseases such as hypertension. Whether risk alleles comprise a small number of common variants or many rare independent mutations at trait loci is largely unknown. We screened members of the Framingham Heart Study (FHS) for variation in three genes—SLC12A3 (NCCT), SLC12A1 (NKCC2) and KCNJ1 (ROMK)—causing rare recessive diseases featuring large reductions in blood pressure. Using comparative genomics, genetics and biochemistry, we identified subjects with mutations proven or inferred to be functional. These mutations, all heterozygous and rare, produce clinically significant blood pressure reduction and protect from development of hypertension. Our findings implicate many rare alleles that alter renal salt handling in blood pressure variation in the general population, and identify alleles with health benefit that are nonetheless under purifying selection. These findings have implications for the genetic architecture of hypertension and other common complex traits. [ABSTRACT FROM AUTHOR]

The multi-subunit H+-ATPase pump is present at particularly high density on the apical (luminal) surface of α-intercalated cells of the cortical collecting duct of the distal nephron, where vectorial proton transport is required for urinary acidification. The complete subunit composition of the apical ATPase, however, has not been fully agreed upon. Functional failure of α-intercalated cells results in a group of disorders, the distal renal tubular acidoses (dRTA), whose features include metabolic acidosis accompanied by disturbances of potassium balance, urinary calcium solubility, bone physiology and growth. Mutations in the gene encoding the B-subunit of the apical pump (ATP6B1) cause dRTA accompanied by deafness. We previously localized a gene for dRTA with preserved hearing to 7q33?34 (ref. 4). We report here the identification of this gene, ATP6N1B, which encodes an 840 amino acid novel kidney-specific isoform of ATP6N1A, the 116-kD non-catalytic accessory subunit of the proton pump. Northern-blot analysis demonstrated ATP6N1B expression in kidney but not other main organs. Immunofluorescence studies in human kidney cortex revealed that ATP6N1B localizes almost exclusively to the apical surface of α-intercalated cells. We screened nine dRTA kindreds with normal audiometry that linked to the ATP6N1B locus, and identified different homozygous mutations in ATP6N1B in eight. These include nonsense, deletion and splice-site changes, all of which will truncate the protein. Our findings identify a new kidney-specific proton pump 116-kD accessory subunit that is highly expressed in proton-secreting cells in the distal nephron, and illustrate its essential role in normal vectorial acid transport into the urine by the kidney. [ABSTRACT FROM AUTHOR]

Pseudohypoaldosteronism type 1 (PHA-1) is an inherited disease characterized by severe neonatal salt-wasting and caused by mutations in subunits of the amiloride-sensitive epithelial sodium channel (ENaC). A missense mutation (G37S) of the human ENaC β subunit that causes loss of ENaC function and PHA-1 replaces a glycine that is conserved in the N-terminus of all members of the ENaC gene family. We now report an investigation of the mechanism of channel inactivation by this mutation. Homologous mutations, introduced into α, β or γ subunits, all significantly reduce macroscopic sodium channel currents recorded in Xenopus laevis oocytes. Quantitative determination of the number of channel molecules present at the cell surface showed no significant differences in surface expression of mutant compared with wild-type channels. Single channel conductances and ion selectivities of the mutant channels were identical to that of wild-type. These results suggest that the decrease in macroscopic Na currents is due to a decrease in channel open probability (Po), suggesting that mutations of a conserved glycine in the N-terminus of ENaC subunits change ENaC channel gating, which would explain the disease pathophysiology. Single channel recordings of channels containing the mutant α subunit (αG95S) directly demonstrate a striking reduction in Po. We propose that this mutation favors a gating mode characterized by short-open and long-closed times. We suggest that determination of the gating mode of ENaC is a key regulator of channel activity. [ABSTRACT FROM AUTHOR]

A correction to the article "Recurrent activating mutation in PRKACA in cortisol-producing adrenal tumors" that was published online in the April 20, 2014 issue is presented.

Mutations in the kinase WNK4 cause an inherited form of human hypertension, pseudohypoaldosteronism type II (PHAII). WNK4 has been shown to regulate the activity of several mediators of renal NaCl and K+ flux. We now show by experiments in Xenopus oocytes and in mice with PHAII-mutant WNK4 that WNK4 regulates the epithelial Na+ channel (ENaC), a major effector of aldosterone signaling. In oocytes, WNK4 inhibits ENaC activity, as measured by amiloride-sensitive whole cell currents (>50%, p< 2 x 10-7), via a kinase-independent mechanism that requires C-termini of the channel's β and γ subunits. A PHAII-causing mutation in WNK4 abolishes this inhibition. SGK1, a known aldosterone-stimulated activator of ENaC, binds WNK4 and specifically phosphorylates it at serine 1169. Mutations that mimic this phosphorylation abrogate WNK4's inhibition of ENaC. We also measured amiloride-sensitive short circuit currents in distal colonic epithelial explants and showed that PHAII mice exhibit 3.5-fold increased ENaC activity (p<0.02) compared to wild type littermates. These studies identify a novel downstream target of WNK4 and show that WNK4 itself is regulated by components of the aldosterone signaling pathway. Moreover, they provide the first functional demonstration of a WNK kinase regulating an ion channel in vivo and reveal a novel role for WNK kinases in regulating salt absorption outside the kidney. [ABSTRACT FROM AUTHOR]

Abstract: Precise regulation of the intracellular concentration of chloride [Cl−]i is necessary for proper cell volume regulation, transepithelial transport, and GABA neurotransmission. The Na–K–2Cl (NKCCs) and K–Cl (KCCs) cotransporters, related SLC12A transporters mediating cellular chloride influx and efflux, respectively, are key determinants of [Cl−]i in numerous cell types, including red blood cells, epithelial cells, and neurons. A common “chloride/volume-sensitive kinase”, or related system of kinases, has long been hypothesized to mediate the reciprocal but coordinated phosphoregulation of the NKCCs and the KCCs, but the identity of these kinase(s) has remained unknown. Recent evidence suggests that the WNK (with no lysine = K) serine–threonine kinases directly or indirectly via the downstream Ste20-type kinases SPAK/OSR1, are critical components of this signaling pathway. Hypertonic stress (cell shrinkage), and possibly decreased [Cl−]i, triggers the phosphorylation and activation of specific WNKs, promoting NKCC activation and KCC inhibition via net transporter phosphorylation. Silencing WNK kinase activity can promote NKCC inhibition and KCC activation via net transporter dephosphorylation, revealing a dynamic ability of the WNKs to modulate [Cl−]. This pathway is essential for the defense of cell volume during osmotic perturbation, coordination of epithelial transport, and gating of sensory information in the peripheral system. Commiserate with their importance in serving these critical roles in humans, mutations in WNKs underlie two different Mendelian diseases, pseudohypoaldosteronism type II (an inherited form of salt-sensitive hypertension), and hereditary sensory and autonomic neuropathy type 2. WNKs also regulate ion transport in lower multicellular organisms, including Caenorhabditis elegans, suggesting that their functions are evolutionarily-conserved. An increased understanding of how the WNKs regulate the Na–K–2Cl and K–Cl cotransporters may provide novel opportunities for the selective modulation of these transporters, with ramifications for common human diseases like hypertension, sickle cell disease, neuropathic pain, and epilepsy. [Copyright &y& Elsevier]