Gitelman syndrome

Navigating the multifaceted intricacies of the Na+-Cl- cotransporter, a highly regulated key effector in the control of hydromineral homeostasis

The Na+-Cl- cotransporter (NCC; SLC12A3) is a highly regulated integral membrane protein that is known to exist as three splice variants in primates. Its primary role in the kidney is to mediate the cosymport of Na+ and Cl- across the apical membrane of the distal convoluted tubule. Through this role and the involvement of other ion transport systems, NCC allows the systemic circulation to reclaim a fraction of the ultrafiltered Na+, K+, Cl-, and Mg+ loads in exchange for Ca2+ and [Formula: see text]. The physiological relevance of the Na+-Cl- cotransport mechanism in humans is illustrated by several abnormalities that result from NCC inactivation through the administration of thiazides or in the setting of hereditary disorders. The purpose of the present review is to discuss the molecular mechanisms and overall roles of Na+-Cl- cotransport as the main topics of interest. On reading the narrative proposed, one will realize that the knowledge gained in regard to these themes will continue to progress unrelentingly no matter how refined it has now become.

Adult classic Bartter syndrome: a case report with 5-year follow-up and literature review

Bartter syndrome (BS) is a rare, inherited salt-losing renal tubular disorder characterized by secondary hyperaldosteronism, hypokalemia, hypochloremia, metabolic alkalosis, and low-to-normal blood pressure. Classic BS, or BS Type 3, the most common subtype in the Asian population, is caused by a molecular defect in ClC-Kb, a voltage-gated chloride channel in renal tubules, due to CLCNKB gene mutation. Because the onset of BS is more common in children than in adults, the diagnosis, treatment outcomes, genotype/phenotype association, and follow-up of adult-onset BS Type 3 are limited. This case report describes the findings in a 20-year-old man who was admitted with hypokalemic paralysis, with clinical manifestations were similar to those of Gitelman syndrome (GS); however, the patient was later diagnosed to have BS Type 3 through genetic testing (NM_000085.4 (CLCNKB): c.1052G>T). A literature review showed that no homozygous mutations have been reported to date. After 5 years of treatment and follow-up, we found that this genotype requires high levels of potassium and is prone to urinary protein and metabolic syndrome. Distinguishing adult-onset BS from GS is challenging in clinical practice. However, genetic diagnosis can help solve this problem effectively, and genotypes play a guiding role in treatment planning.

First Diagnosis of Gitelman Syndrome During Pregnancy in an Adolescent Female: A Case Report

Gitelman syndrome (GS) is an inherited somatic recessive disorder characterized by hypokalemic metabolic alkalosis, accompanied by hypocalciuria and hypermagnesuria. It usually presents in late childhood or young adults with muscle weakness, tetany, or convulsions. Limited information is available in the literature regarding the proper management of this syndrome during pregnancy, as well as its effects on both the mother and the child. We herein present the case of a 16-year-old primigravida who was admitted to the emergency department with chief complaints of abdominal pain, weakness, and vomiting for the past three days during the 12th week of gestation. Routine blood investigations revealed hypokalemia and hypomagnesemia, and electrocardiography (ECG) showed ST-segment depressions. Further evaluation was performed due to persistent hypokalemia, and metabolic alkalosis, hypocalciuria, and hyperaldosteronism were found. Hence, a clinical diagnosis of GS took place. The pregnancy progressed smoothly without complications; potassium levels remained consistently below normal, requiring supplementation three times during pregnancy. Pregnant women with GS should be reported due to the rarity of cases, aiming to establish a standardized approach for monitoring and management.

A novel homozygous SLC12A3 mutation causing Gitelman syndrome with co-existent autoimmune thyroiditis: a case report and review of the literature

Gitelman syndrome is a rare, autosomal recessively inherited tubulopathy manifesting with hypokalemia, hypomagnesemia, hypocalciuria, and metabolic alkalosis. Common symptoms include fatigue, myalgia, reduced performance capacity, tetany, paresthesia, and delayed growth. However, as reported in the literature, diagnosis in some patients is prompted by an incidental finding of hypokalemia. GS develops due to mutations in the SLC12A3 gene, which encodes the thiazide-sensitive Na-Cl cotransporter. Many variants in the SLC12A3 gene causing GS have been reported in literature. A new pathogenic homozygous mutation (c.2612G > T), absence of hypomagnesemia, and accompanying autoimmune thyroiditis are remarkable in our patient. There are a few Gitelman syndrome cases that are complicated with autoimmune thyroiditis in the literature. In this study, we present a case of Gitelman syndrome with a novel homozygous mutation and accompanying autoimmune thyroiditis and review of the literature.

The first compound heterozygous mutations in SLC12A3 and PDX1 genes: a unique presentation of Gitelman syndrome with distinct insulin resistance and familial diabetes insights

Background

Gitelman Syndrome (GS) patients frequently exhibit disrupted glucose metabolism, attributed to hypokalemia, hypomagnesemia and heightened aldosterone. This study delved into the genetic underpinnings linked to insulin resistance and diabetes in a GS patient, contextualized within his family history.

Methods

The hydrochlorothiazide and furosemide loading test were performed to ascertain the presence of GS. Oral glucose tolerance test (OGTT) evaluated glucose metabolism and insulin sensitivity. Whole-exome sequencing, validated by Sanger sequencing, was employed to confirm gene mutations, which were then tracked among the patient's relatives.

Results

Symptoms and laboratory examination confirmed the clinical diagnosis of GS. Comprehensive whole-exome sequencing, augmented by Sanger sequencing validation, revealed a compound heterozygous mutation within the SLC12A3 gene (c.1108G>C in exon 9, c.676G>A in exon 5 and c.2398G>A in exon 20) in the patient. The OGTT affirmed diabetes and heightened insulin resistance, distinct from previous patients with GS we evaluated. Further genetic analysis identified a missense heterozygous mutation (c.97C>G in exon 1) within the PDX1 gene, inherited from the patient's diabetic mother without GS. Furthermore, the patient's brother, with impaired glucose tolerance but regular potassium levels, also bore this mutation, hinting at additional impacts of the PDX1 gene mutation on glucose metabolism regulation beyond the known impacts of GS.

Conclusion

This study unveils unprecedented compound heterozygous mutations in the SLC12A3 and PDX1 genes in a GS patient. These findings illuminate the potential complex genetic factors influencing glucose metabolism disruptions in GS.

Take-home message

This research uncovers a novel combination of SLC12A3 and PDX1 gene mutations in a Gitelman Syndrome patient, revealing intricate genetic factors that potentially disrupt glucose metabolism and shedding light on familial diabetes links.

Novel SLC12A3 gene mutations and clinical characteristics in two pedigrees with Gitelman syndrome

OBJECTIVE

Gitelman syndrome (GS) is an autosomal recessive tubulopathy resulting from inactivating mutations in the SLC12A3 gene that encodes the thiazide-sensitive sodium-chloride cotransporter (NCC). To date, more than 500 mutations have been identified in the SLC12A3 gene. In this study, we identified two new mutations in the SLC12A3 gene in two Chinese GS pedigrees.

DESIGN, PATIENTS AND MEASUREMENTS

The clinical characteristics and laboratory examination of two suspected GS patients in our hospital were analyzed. In addition, two pedigrees including 11 members and 2 patients underwent SLC12A3 gene analysis.

RESULTS

Both patients were middle-aged women with characteristics of hypokalemic metabolic alkalosis, hypomagnesemia, low level of urinary calcium and the elevated levels of renin-angiotensin-aldosterone system. So, they were clinically diagnosed as GS. Patient 2 also had type 2 diabetes and Graves' disease. Both patients were found to carry two mutations of SLC12A3 gene by Sanger direct sequencing, which were all compound heterozygous mutations. We identified three mutations in these two Chinese GS pedigrees, one of which was c.179C>T (Thr60Met). The novel c.2159G>T (p. Gly720Val) and c.2675T>C (p. Leu892Pro) mutations were strongly predicted to be pathogenic using four network programs-Polyphen-2, SIFT, Mutation Taster and LRT.

CONCLUSIONS

We identified two novel SLC12A3 genetic variant [c.2159G>T (p.Gly720Val) and c.2675T>C (p.Leu892Pro)] in two Chinese GS pedigrees. The discovery of new mutations has enriched the spectrum of SLC12A3 genotypes.

Epithelial Transport in Disease: An Overview of Pathophysiology and Treatment

Epithelial transport is a multifaceted process crucial for maintaining normal physiological functions in the human body. This comprehensive review delves into the pathophysiological mechanisms underlying epithelial transport and its significance in disease pathogenesis. Beginning with an introduction to epithelial transport, it covers various forms, including ion, water, and nutrient transfer, followed by an exploration of the processes governing ion transport and hormonal regulation. The review then addresses genetic disorders, like cystic fibrosis and Bartter syndrome, that affect epithelial transport. Furthermore, it investigates the involvement of epithelial transport in the pathophysiology of conditions such as diarrhea, hypertension, and edema. Finally, the review analyzes the impact of renal disease on epithelial transport and highlights the potential for future research to uncover novel therapeutic interventions for conditions like cystic fibrosis, hypertension, and renal failure.

Gitelman Syndrome and Hypertension: A Case Report

In a patient with persistent hypokalemia, it is important to consider Gitelman syndrome, a rare, salt-wasting tubulopathy inherited in an autosomal recessive pattern. Gitelman syndrome leads to electrolyte abnormalities like hypokalemia, hypomagnesemia, and metabolic alkalosis. Typical clinical features include muscle cramps, fatigue, polydipsia, and salt cravings. Our case involves a female patient in her early 40s who visited the endocrinology clinic with symptoms of polyuria, constipation, muscle weakness, and fatigue. Electrolyte abnormalities included hypokalemia, hypomagnesemia, hypochloremia, and hyperreninemia. Initial tests, such as renal function tests, renal ultrasound, and CT scan, yielded normal results. Differential diagnosis of Gitelman syndrome and Bartter syndrome was considered due to the mutual electrolyte abnormalities of hypokalemia and metabolic alkalosis. Bartter syndrome was ruled out in our patient due to the presence of hypomagnesemia, which indicates a different defective receptor. Ultimately, genetic testing would be necessary to confirm the diagnosis of Gitelman syndrome considering the characteristic electrolyte disturbances and classic clinical presentation of fatigue, weakness, and salt craving.

Novel heterozygous mutations of SLC12A3 gene in a Chinese pedigree with Gitelman syndrome: A care-compliant case report

RATIONALE

The diagnosis of Gentleman syndrome (GS) is usually delayed because the clinical symptoms are easily mistaken.

PATIENT CONCERNS

A 19-year-old male patient was referred to endocrinology due to intermittent twitch of extremities for approximately 7 years.

DIAGNOSES

The diagnosis of GS was made based on the laboratory and gene detection results. We identified 2 new variants in the SLC12A3 gene [c.857 A > C (exon7) and c.2089_2095del (exon17)] in his Asian family.

INTERVENTIONS

The patient received the treatment of potassium chloride sustained release tablets, potassium magnesium aspartate and spironolactone. After given potassium supplement through enema, his serum potassium level was corrected to normal.

OUTCOMES

The electrolyte imbalance including hypokalemia and hypomagnesemia were improved with a remission of the clinical manifestations. But the patient's condition still could not remain stable for his irregular oral potassium supplementation during the follow-up of nearly 3 months.

LESSONS

Our finding broadens the variant spectrum of SLC12A3 and contributes to a more quickly genetic counseling. As a result, when a patient presents with persistent, unspecified, and inadequately treated hypokalemia, tests for GS should indeed be considered. For suspected cases of GS, genetic testing should always be considered in the diagnosis.

Heart's Dangerous Symphony: Torsade De Pointes Unleashed by Gitelman Syndrome-Induced Hypomagnesemia

Gitelman syndrome (GS) is a rare autosomal recessive salt-losing renal tubular disorder associated with a mutation of SLC12A3 or CLCNKB genes which encodes the thiazide-sensitive sodium-chloride co-transporter (NCCT) in the distal renal tubule. It is inherited as an autosomal recessive disorder. Hypokalemia, metabolic alkalosis, hypomagnesemia, hypocalciuria, and renin-angiotensin-aldosterone system (RAAS) activation are characteristics of GS. GS is often misdiagnosed or underdiagnosed owing to its low incidence and lack of awareness. Its prevalence is estimated to be around 1-10 per 40,000 people. We report a case of cardiac arrest secondary to torsade de pointes (TdP) because of GS-induced hypomagnesemia. Our case highlights the importance of clinicians being aware of the potential electrolyte abnormalities and complications associated with GS, as it can lead to catastrophic consequences if not identified and corrected earlier.

Two Brothers from Macedonia with Gitelman Syndrome

Gitelman syndrome (GS) is a rare renal tubulopathy with an autosomal recessive mode of inheritance, caused by biallelic pathogenic variants in the SLC12A3 gene. The clinical features may overlap with other disorders, such as Bartter syndrome type 3, HNF1B nephropathy or even mitochondrial disease, but can be distinguished by molecular genetic analysis. Here we report on two preschool brothers, who presented with a several months' history of episodes of carpopedal spasms and muscle aches. The biochemical analyses revealed hypokalemia and hypomagnesemia without metabolic alkalosis. A 24-h urine sample demonstrated hypocalciuria. The molecular analyses showed that both patients were heterozygous for 3 (likely) pathogenic variants in SLC12A3: c.1805_1806del; p. (Tyr602Cysfs*31), c.2660+1G>A and c.2944 A>T; p. (Ile982Phe). Analysis of the parents showed that the mother was heterozygous for the c.2944 A>T p.(Ile982Phe) variant, and the father carried the other 2 variants (c.1805_1806del and c.2660+1G>A). Herein we present two children in a family from N. Macedonia with clinical manifestations and electrolyte imbalances suggestive of GS. The results of the tubulopathy next generation sequencing (NGS) panel confirmed the diagnosis. The boys are treated with a high salt diet and oral potassium and magnesium supplements.

Sudden cardiac arrest in a child with Gitelman syndrome: a case report and literature review

Salt-losing tubulopathies are well-recognised diseases predisposing to metabolic disturbances in affected patients. One of the most severe complications can be life-threatening arrhythmias causing sudden cardiac arrest. We present here the first case of a pediatric patient with Gitelman syndrome associated sudden cardiac arrest without precipitating event. A 10-year-old boy collapsed due to ventricular fibrillation in the Prague tram. Lay cardiopulmonary resuscitation was initiated and external defibrillation restored sinus rhythm within minutes. Initial laboratory examination revealed severe hypokalemia requiring large amounts of electrolyte supplementation. Genetic testing focused to tubulopathies was performed and the diagnosis of Gitelman syndrome was made following the identification of two pathogenic variants in SLC12A3 gene (c.2633 + 1G>A and c.2221G>A). Implantable cardioverter-defibrillator was implanted to prevent sudden cardiac death. The patient was in a good clinical condition with satisfactory electrolyte serum levels at the last follow-up. Causes of electrolyte abnormalities in children should be identified early to prevent the development of rare but potentially fatal complications.

Diabetic ketoacidosis in a patient known with Gitelman syndrome

Gitelman syndrome is a rare hereditary nephropathy, which causes chronic metabolic alkalosis with low potassium and magnesium levels. There is no known coherence between Gitelman syndrome and Type-1 diabetes but patients with both diseases that develop diabetic ketoacidosis might present with normal acid status and receive incorrect treatment. In our case report the patient was known with both diseases and quickly diagnosed and treated but the condition is rare and previously only described in two other case reports.

Genetic diagnosis and treatment of hereditary renal tubular disease with hypokalemia and alkalosis

Renal tubules play an important role in maintaining water, electrolyte, and acid-base balance. Renal tubule dysfunction can cause electrolyte disorders and acid-base imbalance. Clinically, hypokalemic renal tubular disease is the most common tubule disorder. With the development of molecular genetics and gene sequencing technology, hereditary renal tubular diseases have attracted attention, and an increasing number of pathogenic genes related to renal tubular diseases have been discovered and reported. Inherited renal tubular diseases mainly occur due to mutations in genes encoding various specific transporters or ion channels expressed on the tubular epithelial membrane, leading to dysfunctional renal tubular reabsorption, secretion, and excretion. An in-depth understanding of the molecular genetic basis of hereditary renal tubular disease will help to understand the physiological function of renal tubules, the mechanism by which the kidney maintains water, electrolyte, and acid-base balance, and the relationship between the kidney and other systems in the body. Meanwhile, understanding these diseases also improves our understanding of the pathogenesis of hypokalemia, alkalosis and other related diseases and ultimately promotes accurate diagnostics and effective disease treatment. The present review summarizes the most common hereditary renal tubular diseases (Bartter syndrome, Gitelman syndrome, EAST syndrome and Liddle syndrome) characterized by hypokalemia and alkalosis. Further detailed explanations are provided for pathogenic genes and functional proteins, clinical manifestations, intrinsic relationship between genotype and clinical phenotype, diagnostic clues, differential diagnosis, and treatment strategies for these diseases.

Advanced chronic kidney disease with life-threatening hypokalemia due to undiagnosed Gitelman syndrome

We report a case of a 58-year-old woman presenting with symptoms of oliguria, fatigue, anorexia, constipation, hypovolemic signs, and laboratory tests showing severe hypokalemia (1.7 mEq/L), hyponatremia (120 mEq/L), high serum creatinine (SCr, 6.46 mg/dL) and urea (352 mg/dL). The patient had previously been diagnosed with chronic kidney disease (CKD), with SCr up to 2.58 mg/dL 1 year prior, and had in all her previous laboratory tests shown hypokalemia, which was treated with conservative measures and eplerenone despite low-normal blood pressure and normal heart function. A set of coordinated measures were applied to restore the potassium deficit, revert hypovolemic hyponatremia, and support renal function (including 4 dialysis sessions). In addition, a careful diagnostic approach revealed inappropriately high urine sodium and potassium losses, hypocalciuria, and hyperreninemic hyperaldosteronism leading to the diagnosis of Gitelman syndrome and hypokalemia-associated chronic tubulointerstitial nephropathy. Importantly, compliance with a simple set of instructions on high potassium and liberal sodium diet enabled the patient not only to remain euvolemic, free of symptoms, and with normal electrolytes, but also to recover a significant part of renal function and stabilize at an earlier CKD stage. Gitelman syndrome is a rare disorder that can be easily diagnosed and treated following simple measures; its early diagnosis is necessary to avoid life-threatening complications.

Gitelman's Syndrome in Pregnancy With Adverse Foetal Outcome: A Case Report

Gitelman's syndrome (GS) is a disorder characterized by hypokalaemia, hypomagnesemia, hypocalciuric and metabolic alkalosis. Despite the fact that it affects women of child-bearing age, only limited information is available regarding its impact on maternal and foetal outcome. We present the case of an un-booked and un-investigated 23-year-old primigravida who presented with chief complaints of vomiting and loose stools. The patient also complained of absent foetal movements in the last 12 hours. Investigations revealed hypokalaemia and hypomagnesemia and ultrasound revealed intra-uterine foetal demise. The patient was symptomatically relieved after electrolyte correction. Scarce reports on Gitelman's syndrome in pregnancy have been documented with the majority of cases showing positive outcomes for the foetus. We hereby present a report of a primigravida with Gitelman's syndrome and foetal loss which is considered uncommon.

A mosaic mutation in the CLCNKB gene causing Bartter syndrome: A case report

Background

Type III Bartter syndrome (BS) is an autosomal recessive disease caused by mutations in the CLCNKB (chloride voltage-gated channel Kb) gene that encodes CLC-Kb. CLC-Kb is mainly located in the thick ascending limb of Henle's loop and regulates chloride efflux from tubular epithelial cells to the interstitium. Type III BS is characterized by metabolic alkalosis, renal salt wasting, hyperreninemia, and hyperaldosteronism with normal blood pressure.

Case presentation

We reported the case of a 3-day-old girl whose initial symptom we diagnosed as jaundice, but we accidentally found metabolic alkalosis. She showed recurrent metabolic alkalosis, hypokalemia, and hypochloremia and also had hyperreninemia and hyperaldosteronism with normal blood pressure. Both oral potassium supplements and potassium infusion therapy were unable to entirely restore the electrolyte imbalance. She was suspected of Bartter syndrome and genetic tests were performed on her and her parents. Next-generation sequencing identified CLCNKB gene mutation including heterozygous mutation c.1257delC (p.M421Cfs*58) and a low-level mutation c.595G > T (p.E199*); both mutations were also verified in the parents.

Conclusion

We reported the case of a classic Bartter syndrome in a newborn with a heterozygous frameshift mutation and a mosaic non-sense mutation in the CLCNKB gene.

Novel Intronic Mutations of the SLC12A3 Gene in Patients with Gitelman Syndrome

Aim

Mutations in the SLC12A3 gene have been reported to cause Gitelman syndrome (GS), characterized by hypokalemic metabolic alkalosis. The aim of this research is to investigate the genetic mutations and clinical features of patients with clinical suspicion of GS.

Methods

Six families were enrolled. The symptoms, clinical examination, laboratory results, genotypes, and effect of mutations on mRNA splicing were analyzed. Genomic DNA was screened for gene variations using whole exome sequence and Sanger sequencing. DNA sequences were compared with reference sequences.

Results

Genetic analysis revealed nine genetic variants of SLC12A3, including three novel heterozygous mutations (c.1096-2A>G, c.1862A>G, and c.2747+4del) and six previously characterized mutations (c.965-1_976delinsACCGAAAATTTT, c.506-1G>A, c.602-16G>A, c.533C >T, c.1456 G>A, and c.1108 G>C). Probands presented with the clinical syndrome of hypokalemia, increased plasma renin, hypocalciuria and hypokalemic alkalosis.

Conclusion

These clinical manifestations and genotypes were consistent with the diagnostic criteria of GS. The study described the phenotypes and genotypes of six pedigrees involving GS patients, demonstrating the importance of SLC12A3 gene screening for GS. This study expands the mutation spectrum of SLC12A3 gene in GS.

Cardiac Arrest as the First Presentation of Gitelman Syndrome

Gitelman syndrome is a salt-wasting tubulopathy characterized by profound hypokalemia, hypomagnesemia, metabolic alkalosis, and hypocalciuria. Cardiac arrest is a relatively rare manifestation of Gitelman syndrome. Here we present a case of Gitelman syndrome in a patient with recurrent cardiac arrest. A 43-year-old female was admitted for out-of-hospital cardiac arrest secondary to ventricular fibrillation. Initial workup revealed severe hypokalemia, hypomagnesemia, metabolic alkalosis, and prolonged QTc. The workup revealed a picture of salt-wasting tubulopathy with hypokalemia, hypomagnesemia, and hypocalciuria. Potassium was repleted aggressively, and the patient received potassium-sparing agents resulting in the stabilization of potassium levels. Before discharge, an implantable cardioverter defibrillator (ICD) was placed for secondary prevention of cardiac arrest. The patient remained symptom-free, and electrolytes remained stable. This case highlights the diagnostic challenges of Gitelman syndrome and the importance of accurate diagnosis in improving patient outcomes.

Gitelman syndrome diagnosed in the first trimester of pregnancy: a case report and literature review

Objectives

Gitelman syndrome is a rare salt-losing tubulopathy caused by inactivating mutations in the SLC12A3 gene, which is expressed in the distal convoluted tubule and accounts for 5–10% of renal sodium reabsorption. Atypical symptoms and insidious conditions generally delay diagnosis until childhood or even adulthood. Here, we report the case of a 22-year-old Chinese woman who was admitted to our endocrinology department for severe hypokalemia during pregnancy.

Case presentation

The patient had no specific symptoms but exhibited hypokalemia, metabolic alkalosis, hypomagnesemia, hypocalciuria, hyperreninemia, hyperaldosteronism, and normal blood pressure. Together, these symptoms indicated the clinical diagnosis of Gitelman syndrome, which was confirmed by genetic analysis. Many drugs have limited safety data during early pregnancy, and optimum potassium and magnesium levels are necessary for a successful pregnancy.

Conclusions

Diagnosis and management of Gitelman syndrome are crucial during pregnancy to ensure the safety of the mother and fetus, especially during the first trimester.

The Impact of Gitelman Syndrome on Cardiovascular Disease: From Physiopathology to Clinical Management

Gitelman syndrome (GS), or congenital hypokalemic hypomagnesemia hypocalciuria with metabolic alkalosis, is a congenital inherited tubulopathy. This tubulopathy is associated with disorders of water-electrolyte homeostasis, such as metabolic alkalosis, hypokalemia, hyponatremia, hypomagnesemia and hypocalciuria. GS has an autosomal recessive inheritance. The loss-of-function mutation involves the gene that codifies for thiazide-sensitive sodium-chloride co-transporter located in the distal convoluted tubule. The physiopathology of the syndrome is characterized by activation of the renin-angiotensin-aldosterone system (RAAS) with a low plasmatic concentration of angiotensin-II. Despite hyper-activation of RAAS, average or low blood pressure is detected in association with low peripheral resistance and reduced response to vasopressors. Clinical findings are brief episodes of fatigue, syncope, vertigo, ataxia and blurred vision; sudden cardiac death might occur. This review aims to give insight into cardiovascular implications and management of GS.

A novel mutation of SLC12A3 gene causing Gitelman syndrome

A 48-year-old patient with a history of diabetes mellitus, presented to a surgical ward with abdominal pain. She was found to have hypokalemia. Her younger sister had passed away due to sudden cardiac death at the age of 25 years. Further evaluation revealed an elevated trans-tubular potassium gradient suggestive of renal potassium loss, normal blood pressure, hypomagnesemia, hypocalciuria, and alkalosis. Moreover, there was evidence of secondary hyperaldosteronism. Genetic studies revealed two heterozygous mutations of the SLC12A3 gene, including a novel mutation which has not been reported before anywhere in the world. She was treated with intravenous potassium supplementation and was later converted to oral potassium and oral magnesium supplementation with spironolactone. Her potassium and magnesium levels normalized and glycaemic control also improved. Hypokalemia and hypomagnesemia found in Gitelman syndrome may be associated with insulin resistance and correction of electrolytes can lead to better glycaemic control.

Mechanisms of ion transport regulation by HNF1β in the kidney: beyond transcriptional regulation of channels and transporters

Hepatocyte nuclear factor 1β (HNF1β) is a transcription factor essential for the development and function of the kidney. Mutations in and deletions of HNF1β cause autosomal dominant tubule interstitial kidney disease (ADTKD) subtype HNF1β, which is characterized by renal cysts, diabetes, genital tract malformations, and neurodevelopmental disorders. Electrolyte disturbances including hypomagnesemia, hyperuricemia, and hypocalciuria are common in patients with ADTKD-HNF1β. Traditionally, these electrolyte disturbances have been attributed to HNF1β-mediated transcriptional regulation of gene networks involved in ion transport in the distal part of the nephron including FXYD2, CASR, KCNJ16, and FXR. In this review, we propose additional mechanisms that may contribute to the electrolyte disturbances observed in ADTKD-HNF1β patients. Firstly, kidney development is severely affected in Hnf1b-deficient mice. HNF1β is required for nephron segmentation, and the absence of the transcription factor results in rudimentary nephrons lacking mature proximal tubule, loop of Henle, and distal convoluted tubule cluster. In addition, HNF1β is proposed to be important for apical-basolateral polarity and tight junction integrity in the kidney. Interestingly, cilia formation is unaffected by Hnf1b defects in several models, despite the HNF1β-mediated transcriptional regulation of many ciliary genes. To what extent impaired nephron segmentation, apical-basolateral polarity, and cilia function contribute to electrolyte disturbances in HNF1β patients remains elusive. Systematic phenotyping of Hnf1b mouse models and the development of patient-specific kidney organoid models will be essential to advance future HNF1β research.

Genetic and Biological Effects of SLC12A3, a Sodium-Chloride Cotransporter, in Gitelman Syndrome and Diabetic Kidney Disease

The SLC12A3 (Solute carrier family 12 member 3) gene encodes a sodium-chloride cotransporter and mediates Na+ and Cl− reabsorption in the distal convoluted tubule of kidneys. An experimental study has previously showed that with knockdown of zebrafish ortholog, slc12a3 led to structural abnormality of kidney pronephric distal duct at 1-cell stage, suggesting that SLC12A3 may have genetic effects in renal disorders. Many clinical reports have demonstrated that the function-loss mutations in the SLC12A3 gene, mainly including Thr60Met, Asp486Asn, Gly741Arg, Leu859Pro, Arg861Cys, Arg913Gln, Arg928Cys and Cys994Tyr, play the pathogenic effects in Gitelman syndrome. This kidney disease is inherited as an autosomal recessive trait. In addition, several population genetic association studies have indicated that the single nucleotide variant Arg913Gln in the SLC12A3 gene is associated with diabetic kidney disease in type 2 diabetes subjects. In this review, we first summarized bioinformatics of the SLC12A3 gene and its genetic variation. We then described the different genetic and biological effects of SLC12A3 in Gitelman syndrome and diabetic kidney disease. We also discussed about further genetic and biological analyses of SLC12A3 as pharmacokinetic targets of diuretics.

Three uncommon mutations of the SLC12A3 gene in gitelman syndrome: case reports and review of the literature

Background

Gitelman syndrome is a rare autosomal recessive salt-wasting tubulopathy characterized by low potassium and magnesium levels in the blood, decreased excretion of calcium in the urine, and metabolic alkalosis. It is commonly caused by an inactivating mutation in the SLC12A3 gene (16q13), which encodes a thiazide-sensitive sodium chloride cotransporter. Here, we present three cases with the same clinical and laboratory findings that showed different mutations in the SLC12A3 gene.

Case presentation

Three children, a 14-year-old boy, a 7-year-old girl, and an 11-year-old boy, were admitted to our hospital at different times with nausea, weakness, muscle cramps in hands, and failure to thrive complaints. Blood tests showed hypokalemia, hypomagnesemia and metabolic alkalosis. Patients were referred to Pediatric Nephrology Clinic and diagnosed with Gitelman syndrome. Genetic tests of three cases showed homozygous mutations of c.1928C > T, p.Pro643Leu, c.248G > A, p.Arg83Gln, and c.1919A > G, p.N640S in the SLC12A3 gene exists, respectively. Potassium chloride, magnesium replacements, and indomethacin were given for treatment to patients. During follow-up, patients' heights and weights were increased dramatically, and nausea complaints were over.

Conclusion

Different mutations in the SLC12A3 gene in Gitelman syndrome can be detected but clinical, and laboratory findings were generally similar. Treatment with potassium, magnesium supplements, and indomethacin showed significant improvements in symptoms.

Gitelman syndrome, hypomagnesemia, and venous thrombosis: An intriguing association

Among salt‐wasting tubulopathies' complications, venous thrombosis is one of the rarest. We report a case of a young woman with Gitelman syndrome (GS). She presented a deep venous thrombosis in her leg and was treated with heparin with favorable outcomes. We retained hypomagnesemia as the cause of the thrombosis.

Rapidly Progressing to ESRD in an Individual with Coexisting ADPKD and Masked Klinefelter and Gitelman Syndromes

Autosomal dominant polycystic kidney disease (ADPKD) is the most common monogenetic hereditary renal disease, promoting end-stage renal disease (ESRD). Klinefelter syndrome (KS) is a consequence of an extra copy of the X chromosome in males. Main symptoms in KS include hypogonadism, tall stature, azoospermia, and a risk of cardiovascular diseases, among others. Gitelman syndrome (GS) is an autosomal recessive disorder caused by SLC12A3 variants, and is associated with hypokalemia, hypomagnesemia, hypocalciuria, normal or low blood pressure, and salt loss. The three disorders have distinct and well-delineated clinical, biochemical, and genetic findings. We here report a male patient with ADPKD who developed early chronic renal failure leading to ESRD, presenting with an intracranial aneurysm and infertility. NGS identified two de novo PKD1 variants, one known (likely pathogenic), and a previously unreported variant of uncertain significance, together with two SLC12A3 pathogenic variants. In addition, cytogenetic analysis showed a 47, XXY karyotype. We investigated the putative impact of this rare association by analyzing possible clinical, biochemical, and/or genetic interactions and by comparing the evolution of renal size and function in the proband with three age-matched ADPKD (by variants in PKD1) cohorts. We hypothesize that the coexistence of these three genetic disorders may act as modifiers with possible synergistic actions that could lead, in our patient, to a rapid ADPKD progression.

Gitelman syndrome: A first published clinical association with chronic pancreatitis, a case report and review of literature

Introduction and importance

Gitelman syndrome (GS) is an autosomal recessive, salt-losing tubulopathy, also referred to as familial hypokalemia-hypomagnesemia, caused by mutation of genes encoding the sodium chloride cotransporter (NCCT) and magnesium transporters in the thiazide sensitive segments of the distal convoluted tubule (DCT) of the nephron. Patients may present with a spectrum of clinical presentations and associations.

Case presentation

Here, we report a case of a 39-year-old female with Gitelman syndrome and chronic pancreatitis in the absence of well-known causes of CP. Her clinical and radiographic profile constituted an indication for surgical intervention, namely pancreatic head and body coring and pancreaticojejunostomy (Frey's procedure) (FP). On follow up 3 month later, the patient is pain-free and is satisfied. To the best of our knowledge and based on literature review, this is the first reported case of GS with CP.

Conclusion

The purpose of this paper is to describe a case of CP in association with established GS as a first published clinical association, raising a possibility of another possible clinical manifestation of GS. Further observational studies are encouraged to support this association.

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Gitelman Syndrome is a rare disease with many different associations. Before this case report, it was never reported to be associated with chronic pancreatitis.

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Our reported patient has been having multiple attacks of acute on top of chronic pancreatitis, despite the negative history of predisposing factors of chronic pancreatitis

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The purpose of this report is to discuss the clinical and radiological findings of such disease, the proposed surgical treatment and the approach in light of our experience.

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We hope after publishing this case report to help and to put such association under the microscope in the hope of improving the patients’ outcome.

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Further studies are needed to support or challenge this association and to better understand the pathophysiology of chronic pancreatitis in patients with Gitelman syndrome.

Renal calcium and magnesium handling in Gitelman syndrome

Gitelman syndrome (GS) is an autosomal recessive salt-losing tubulopathy caused by biallelic inactivating mutations in the SLC12A3 gene. This gene encodes the thiazide-sensitive sodium-chloride cotransporter (NCC) which is exclusively expressed in the distal convoluted tubules (DCT). GS patients classically present with hypokalemic metabolic alkalosis with hypocalciuria and hypomagnesemia. While hypokalemia and metabolic alkalosis are easily explained by effects of the genotypic defect in GS, the mechanisms by which hypomagnesemia and hypocalciuria develop in GS are poorly understood. In this review, we aim to achieve three major objectives. First, present a concise discussion about current understanding on physiologic calcium and magnesium handling in the DCT. Second, integrate expression data from studies on calciotropic and magnesiotropic proteins relevant to the GS disease state. Lastly, provide insights into the possible mechanisms of calcium-magnesium crosstalk relating to the co-occurrence of hypocalciuria and hypomagnesemia in GS models. Our analyses highlight specific areas of study that are valuable in elucidating possible molecular pathways of hypocalciuria and hypomagnesemia in GS.

Euglycemic Diabetic Ketoacidosis Due to SGLT2 Inhibitor in a Patient With Gitelman Syndrome: A Therapeutic Dilemma

Euglycemic diabetic ketoacidosis (DKA) is a rarely reported side effect of sodium-glucose cotransporter-2 inhibitor (SGLT2i) empagliflozin. A 51-year-old female with Gitelman syndrome and type 2 diabetes mellitus (DM) presented with abdominal pain after a recent hospitalization for acute pancreatitis. Her diabetes medications included metformin, pioglitazone, and empagliflozin. Diabetic ketoacidosis was suspected; however, glucose levels were below the cutoff for DKA; therefore, she was diagnosed with euglycemic DKA. Her pancreatitis workup was insignificant. Severe symptomatic hypokalemia despite aggressive repletion limited the management of DKA with insulin infusion therapy. As her ketonemia resolved, she was initiated on subcutaneous insulin with a small but acceptable decrease in potassium. The therapeutic dilemma of managing euglycemic DKA due to SGLT2i in a patient with Gitelman syndrome has not been previously described.

Clinical and Genetic Approach to Renal Hypomagnesemia

Magnesium (Mg²⁺) is an important intracellular cation and essential to maintain cell function including cell proliferation, immunity, cellular energy metabolism, protein and nucleic acid synthesis, and regulation of ion channels. Consequences of hypomagnesemia affecting multiple organs can be in overt or subtle presentations. Besides detailed history and complete physical examination, the assessment of urinary Mg²⁺ excretion is help to differentiate renal from extra-renal (gastrointestinal, tissue sequestration, and shifting) causes of hypomagnesemia. Renal hypomagnesemia can be caused by an increased glomerular filtration and impaired reabsorption in proximal tubular cells, thick ascending limb of the loop of Henle or distal convoluted tubules. A combination of renal Mg²⁺ wasting, familial history, age of onset, associated features, and exclusion of acquired etiologies point to inherited forms of renal hypomagnesemia. Based on clinical phenotypes, its definite genetic diagnosis can be simply grouped into specific, uncertain, and unknown gene mutations with a priority of genetic approach methods. An unequivocal molecular diagnosis could allow for prediction of clinical outcome, providing genetic counseling, avoiding unnecessary studies or interventions, and possibly uncovering the pathogenic mechanism. Given numerous identified genes responsible for Mg²⁺ transport in renal hypomagnesemia over the past two decades, several potential and specific molecular and cellular therapeutic strategies to correct hypomagnesemia are promising.

Peripartum Management of Gitelman Syndrome for Vaginal Delivery: A Case Report and Review of Literature

We describe the anesthetic management of a spontaneous vaginal delivery at 38 weeks' gestation in a 36-year-old patient with Gitelman syndrome (GS). GS is a rare autosomal recessive renal tubulopathy characterized by hypomagnesemia, hypocalciuria, and secondary aldosteronism, which results in hypokalemia and metabolic alkalosis. To minimize any increase in catecholamine levels and consequent risk of ventricular arrhythmias, a labor epidural analgesia was administered using ropivacaine and fentanyl, along with intravenous magnesium and potassium supplementation. Ropivacaine was substituted for routine bupivacaine to decrease the risk of drug-induced cardiotoxicity. In the event of a cesarean section, the anesthetic plan was to continue with top-up epidural anesthesia and in case of failure, to convert to general anesthesia using propofol and rocuronium for induction. Delivery outcome was successful and uneventful.

A Challenging Case of Persisting Hypokalemia Secondary to Gitelman Syndrome

There are several causes of hypokalemia, including transcellular shift, renal loss, gastrointestinal loss, and decreased oral intake. Sometimes it is challenging to know the source of the problem; however, with detailed history, physical examination, and appropriate laboratory investigations, the physician should be able to narrow down the differentials diagnosis to reach the right one. One of the rare causes of hypokalemia is Gitelman syndrome, which is a salt-losing tubulopathy that manifests as renal potassium wasting, metabolic alkalosis, hypokalemia, hypomagnesemia, hypocalciuria, and hyperreninemic hyperaldosteronism. This disorder is inherited in an autosomal recessive pattern with an incidence of 25 instances per million population. We report a challenging case of persistent hypokalemia in a 30-year-old woman who presented with a history of palpitation, bilateral upper and lower limbs numbness, nausea, diarrhea, and generalized fatigue for three days. After history and physical examination, the patient was diagnosed with an episode of enteritis, and laboratory workups revealed low potassium and magnesium levels, and it was thought that these electrolyte abnormalities were secondary to gastrointestinal loss. Therefore, the patient was mainly treated supportively along with potassium and magnesium replacement. However, after one week of replacement, the patient still had low potassium and magnesium levels in spite of being diarrhea-free, so renal loss was suspected. Urine electrolytes revealed high renal potassium loss with low-normal blood pressure, arterial blood gases revealed metabolic alkalosis with a pH of 7.49 and bicarbonate level of 29 mEq/L. Repeated urine chemistry was done to check for chloride level and turned out to be high, and 24-hour urinary excretion of calcium was very low. Therefore, the patient was diagnosed with Gitelman syndrome and was managed with potassium and magnesium replacements intravenously, and was encouraged to consume a diet rich in these electrolytes. After complete resolutions of the symptoms and correction of potassium and magnesium levels, the patient was discharged home in stable condition.

Calcium Pyrophosphate Crystal Deposition in a Cohort of 57 Patients with Gitelman Syndrome

OBJECTIVE

Gitelman syndrome (GS) is the most frequent salt-wasting genetic tubulopathy and a source of hypokalaemia and hypomagnesemia. Chondrocalcinosis (CC) is a frequent feature of GS. The aim of our study was to determine the prevalence, distribution patterns, clinical phenotypes and risk factors of CC in GS.

METHODS

This prospective study of a cohort of 57 patients with GS included a systematic screening for CC by peripheral joint radiography, cervical spine computerized tomography (CT) and joint ultrasonography. The prevalence of cervical C1-C2 CC by CT was compared between 33 GS patients and sex- and age-matched controls. Clinical and biochemical features were analysed to identify factors associated with CC.

RESULTS

Mean age of patients was 46.5 ± 12.4 years, 66.7% were women, and 93.0% carried SLC12A3 mutations. Mean serum magnesium level was 0.60 ± 0.30 mmol/l. CC was observed in 79% of patients, with the highest prevalence at the cervical spine (81.8%) followed by the knee (52.6%), wrist (50.9%), ankle (38.6%), temporomandibular joint (36.4%), shoulder (33.3%), hip (22.8%), elbow (14.0%) and sclero-choroid (12.1%). Prevalence of CC at the C1-C2 level was higher in the GS cohort than control group (72.7% vs 9.1%) (adjusted odds ratio 21.0, 95% CI 2.8-156.1, p= 0.003). Independent factors associated with CC were low serum magnesium level and age.

CONCLUSION

GS was associated with widespread CC, favoured by aging and hypomagnesemia. The C1-C2 level was the most affected site. Follow-up of this unique cohort will help understanding the clinical consequences of CC, especially the precise characterization of pyrophosphate arthropathy.

The First Korean Case of SLC12A3 Aberrant Skipping of Two Exons Detected by RNA Splicing Analysis

Gitelman syndrome is a salt-losing tubular disorder that is transmitted as an autosomal recessive trait. Variants in the SLC12A3 gene are found in the majority of Gitelman syndrome patients. A 26-year-old woman visited the genetic counseling clinic. Her fiancé was a known Gitelman syndrome patient who was previously diagnosed with 2 pathogenic variants in SLC12A3. In advance of marriage and future family planning, she wanted to perform genetic testing of SLC12A3. A silent exonic variant c.1050G>A was found, and multiple splice site in silico algorithms predicted this variant to have potential alteration of splicing. This variant was classified as “variant of uncertain significance,” and RNA splicing analysis was additionally performed. RNA splicing analysis showed aberrant splicing of exon 7–8 skipping. The result points out the potential pathogenicity of this variant, which should be considered a candidate of variant reclassification in the future. We highly recommend the performance of additional RNA splicing analysis, especially for silent variants predicted to have potential alteration of splicing.

Allele-specific RT-PCR for the rapid detection of recurrent SLC12A3 mutations for Gitelman syndrome

Recurrent mutations in the SLC12A3 gene responsible for autosomal recessive Gitelman syndrome (GS) are frequently reported, but the exact prevalence is unknown. The rapid detection of recurrent SLC12A3 mutations may help in the early diagnosis of GS. This study was aimed to investigate the prevalence of recurrent SLC12A3 mutations in a Taiwan cohort of GS families and develop a simple and rapid method to detect recurrent SLC12A3 mutations. One hundred and thirty independent Taiwan families with genetically confirmed GS were consecutively enrolled to define recurrent SLC12A3 mutations and determine their prevalence. Using TaqMan probe-based real-time polymerase chain reaction, we designed a mutation detection plate with all recurrent mutations. We validated this mutation detection plate and tested its feasibility in newly diagnosed GS patients. A total of 57 mutations in the SLC12A3 gene were identified and 22 including 2 deep intronic mutations were recurrent mutations consisting of 87.1% (242/278, 18 triple) of all allelic mutations. The recurrent mutation-based TaqMan assays were fully validated with excellent sensitivity and specificity in genetically diagnosed GS patients and healthy subjects. In clinical validation, recurrent mutations were recognized in 92.0% of allelic mutations from 12 GS patients within 4 h and all were confirmed by direct sequencing. Recurrent SLC12A3 mutations are very common in Taiwan GS patients and can be rapidly identified by this recurrent mutation-based SLC12A3 mutation plate.

Three Novel Homozygous Mutations of the SLC12A3 Gene in a Gitelman Syndrome Patient

Aim

Gitelman syndrome (GS) is an autosomal recessive disorder characterized by hypokalemic metabolic alkalosis. In this study, we investigated the clinical presentation and sequenced 26 exons of SLC12A3 gene in a patient with a clinical suspicion of GS.

Methods

Clinical work-up including clinical examination, electrocardiography (ECG), chest X-ray, bone mineral density (BMD), and ultrasound examination was conducted and all exons of SLC12A3 gene were analyzed by whole-exome sequencing.

Results

The patient showed hypokalemia, hypomagnesemia, and metabolic alkalosis and was found to have four novel homozygous missense mutations including one known mutation (c.1456 G>A in exon 12) and three novel mutations (c.366A > G in exon 2, c.791C > G in exon 6 and c.1027C > T in exon 8).

Conclusion

Four mutation sites of SLC12A3 gene were found in the patient, three of which have not been reported before. These results may be useful for better understanding the function of this gene and can assist clinicians with treatment decision-making.

Diagnosis and outpatient management of Gitelman syndrome from the first trimester of pregnancy

A 32-year-old woman presented with an incidental finding of hypokalaemia on routine bloods at 9 weeks of a second pregnancy, on a background of lifelong salt craving. Her previous pregnancy was uncomplicated. She had no previous significant medical or family history. Venous blood gases showed a hypokalaemic, normochloraemic metabolic alkalosis. Urinary potassium was elevated. Escalating doses of oral supplementation of potassium, magnesium, sodium and potassium-sparing diuretics were required through the course of pregnancy, in response to regular electrolyte monitoring. These were later weaned and completely stopped post partum. Delivery was uneventful with no maternal or neonatal complications. Genetic testing performed post partum showed heterogenous mutation of SCL12A3 gene.

Review and Analysis of Two Gitelman Syndrome Pedigrees Complicated with Proteinuria or Hashimoto's Thyroiditis Caused by Compound Heterozygous SLC12A3 Mutations

Gitelman syndrome (GS) is an autosomal recessive inherited salt-losing renal tubular disease, which is caused by a pathogenic mutation of SLC12A3 encoding thiazide-sensitive Na-Cl cotransporter, which leads to disturbance of sodium and chlorine reabsorption in renal distal convoluted tubules, resulting in phenotypes such as hypovolemia, renin angiotensin aldosterone system (RAAS) activation, hypokalemia, and metabolic alkalosis. In this study, two GS families with proteinuria or Hashimoto's thyroiditis were analyzed for genetic-phenotypic association. Sanger sequencing revealed that two probands carried SLC12A3 compound heterozygous mutations, and proband A carried two pathogenic mutations: missense mutation Arg83Gln, splicing mutation, or frameshift mutation NC_000016.10:g.56872655_56872667 (gcggacatttttg>accgaaaatttt) in exon 8. Proband B carries two missense mutations: novel Asp839Val and Arg904Gln. Both probands manifested hypokalemia, hypomagnesemia, hypocalcinuria, metabolic alkalosis, and RAAS activation; in addition, the proband A exhibited decreased urinary chloride, phosphorus, and increased magnesium ions excretion, complicated with Hashimoto's Thyroiditis, while the proband B exhibited enhanced urine sodium excretion and proteinuria. The older sister of proband B with GS also had Hashimoto's thyroiditis. Electron microscopy revealed swelling and vacuolar degeneration of glomerular epithelial cells, diffuse proliferation of mesangial cells and matrix, accompanied by a small amount of low-density electron-dense deposition, and segmental fusion of epithelial cell foot processes in proband B. Light microscopy showed mild mesangial hyperplasia in the focal segment of the glomerulus, hyperplasia, and hypertrophy of juxtaglomerular apparatus cells, mild renal tubulointerstitial lesions, and one glomerular sclerosis. So, long-term hypokalemia of GS can cause kidney damage and may also be susceptible to thyroid disease.

Genetic and drug-induced hypomagnesemia: different cause, same mechanism

Magnesium (Mg2+) plays an essential role in many biological processes. Mg2+ deficiency is therefore associated with a wide range of clinical effects including muscle cramps, fatigue, seizures and arrhythmias. To maintain sufficient Mg2+ levels, (re)absorption of Mg2+ in the intestine and kidney is tightly regulated. Genetic defects that disturb Mg2+ uptake pathways, as well as drugs interfering with Mg2+ (re)absorption cause hypomagnesemia. The aim of this review is to provide an overview of the molecular mechanisms underlying genetic and drug-induced Mg2+ deficiencies. This leads to the identification of four main mechanisms that are affected by hypomagnesemia-causing mutations or drugs: luminal transient receptor potential melastatin type 6/7-mediated Mg2+ uptake, paracellular Mg2+ reabsorption in the thick ascending limb of Henle's loop, structural integrity of the distal convoluted tubule and Na+-dependent Mg2+ extrusion driven by the Na+/K+-ATPase. Our analysis demonstrates that genetic and drug-induced causes of hypomagnesemia share common molecular mechanisms. Targeting these shared pathways can lead to novel treatment options for patients with hypomagnesemia.

[Sectio Caesarea under Gitelman Syndrome]

Gitelman syndrome is a rare inherited renal tubulopathy characterized by hypokalemia, hypomagnesemia and metabolic alcalosis. It is caused by a mutation in the SLC12A3 gene leading to a dysfunction of the thiazide-sensitive sodium chloride cotransporter and the magnesium transporters in the distal convoluted tubules. Only few reports of pregnant woman with Gitelman syndrome exist. Due to many unsolved questions about the impact on pregnancy and the maternal and fetal outcome, the obstetric and anesthesiological management remains a challenge. We discuss the case of a primary cesarean delivery in a 22-year-old woman with a new diagnosed Gitelman syndrome focusing on the anesthesiological approach.

Gitelman Syndrome Provisionally Diagnosed During the First Presentation of Diabetic Ketoacidosis

Gitelman syndrome (GS) is an autosomal recessive disease characterized by hypokalemia, hypomagnesemia, metabolic alkalosis, and hypocalciuria. It is caused by mutations in gene SLC12A3 (located in chromosome 16q) encoding NaCl cotransporter. GS is usually asymptomatic for several years and is diagnosed in late childhood or adulthood. The association between GS and diabetic ketoacidosis (DKA) is rare. We present a case of a 25-year-old man with newly diagnosed diabetes mellitus and DKA with profound hypokalemia and hypomagnesemia who was provisionally found to have GS.

A novel homozygous mutation (p.N958K) of SLC12A3 in Gitelman syndrome is associated with endoplasmic reticulum stress

PURPOSE

Gitelman syndrome (GS) is an autosomal recessive renal tubular disease that arises as a consequence of mutations in the SLC12A3 gene, which codes for an Na-Cl cotransporter (NCC) in distal renal tubules. This study was designed to explore the mutations associated with GS in an effort to more fully understand the molecular mechanisms governing GS.

METHODS

We analyzed SLC12A3 mutations in a pedigree including a 42-year-old male with GS as well as four related family members over three generations using Sanger and next generation sequencing approaches. We additionally explored the functional ramifications of identified mutations using both Xenopus oocytes and the HEK293T cell line.

RESULTS

We found that the subject with GS exhibited characteristic symptoms including sporadic thirst, fatigue, excess urination, and substantial hypokalemia and hypocalciuria, although magnesium levels were normal. Other analyzed subjects in this pedigree had normal laboratory findings and did not exhibit clear signs of GS. Sequencing analyses revealed that the GS subject exhibited a homozygous missense mutation (c.2874C > G, p.N958K) in exon 24 of SLC12A3. Both parents of this GS subject, as well as his older brother and daughter all exhibited heterozygous mutations at this same site. Functional analyses in Xenopus oocytes indicated that this mutated SLC12A3 gene encodes a protein which fails to mediate normal sodium transport, and when this mutant gene was expressed in HEK293T cells, we observed significant increases in endoplasmic reticulum (ER)-stress pathway activation.

CONCLUSION

The p.N958K mutation in exon 24 of SLC12A3 can trigger GS at least in part via enhancing ER stress responses.

Gitelman syndrome, a rare cause of refractory hypokalemia. A case repor

Introduction: Gitelman syndrome is a rare hereditary primary renal tubular disorder, with a prevalence of approximately 1 to 10 cases per 40 000 people. It does not have specific symptoms, so its diagnosis depends on high clinical suspicion by the treating physical and a sequential approach to hypokalemia, especially in young patients. Thus, a diagnostic algorithm is proposed at the end of this report. Case presentation: A 23-year-old woman with a history of hospitalization due to hypokalemia presented to the emergency service with intermittent cramping in her lower limbs, which was exacerbated by gastrointestinal symptoms. Laboratory tests reported the following findings: metabolic alkalosis, elevated levels of potassium, magnesium, chloride and sodium in urine, and reduced levels of calcium in urine. Thus, potassium supplementation and eplerenone administration were started, obtaining the complete resolution of symptoms. At her last follow-up appointment, the patient was asymptomatic, and her serum electrolyte levels were normal. In addition, during her hospital stay and due to the high suspicion of Gitelman syndrome, a genetic study was performed, which reported a mutation of the SCL12A3 gene, confirming the diagnosis. Conclusion: The sequential approach to a patient with recurrent hypokalemia is very important to reach an accurate diagnosis among a wide range of differential diagnoses.

Mechanisms coupling sodium and magnesium reabsorption in the distal convoluted tubule of the kidney

Hypomagnesaemia is a common feature of renal Na+ wasting disorders such as Gitelman and EAST/SeSAME syndrome. These genetic defects specifically affect Na+ reabsorption in the distal convoluted tubule, where Mg2+ reabsorption is tightly regulated. Apical uptake via TRPM6 Mg2+ channels and basolateral Mg2+ extrusion via a putative Na+ -Mg2+ exchanger determines Mg2+ reabsorption in the distal convoluted tubule. However, the mechanisms that explain the high incidence of hypomagnesaemia in patients with Na+ wasting disorders of the distal convoluted tubule are largely unknown. In this review, we describe three potential mechanisms by which Mg2+ reabsorption in the distal convoluted tubule is linked to Na+ reabsorption. First, decreased activity of the thiazide-sensitive Na+ /Cl- cotransporter (NCC) results in shortening of the segment, reducing the Mg2+ reabsorption capacity. Second, the activity of TRPM6 and NCC are determined by common regulatory pathways. Secondary effects of NCC dysregulation such as hormonal imbalance, therefore, might disturb TRPM6 expression. Third, the basolateral membrane potential, maintained by the K+ permeability and Na+ -K+ -ATPase activity, provides the driving force for Na+ and Mg2+ extrusion. Depolarisation of the basolateral membrane potential in Na+ wasting disorders of the distal convoluted tubule may therefore lead to reduced activity of the putative Na+ -Mg2+ exchanger SLC41A1. Elucidating the interconnections between Mg2+ and Na+ transport in the distal convoluted tubule is hampered by the currently available models. Our analysis indicates that the coupling of Na+ and Mg2+ reabsorption may be multifactorial and that advanced experimental models are required to study the molecular mechanisms.

Glomerular podocyte dysfunction in inherited renal tubular disease

BACKGROUND

Hereditary renal tubular disease can cause hypercalciuria, acid-base imbalance, hypokalemia, hypomagnesemia, rickets, kidney stones, etc. If these diseases are not diagnosed or treated in time, they can cause kidney damage and electrolyte disturbances, which can be detrimental to the maturation and development of the child. Glomerular involvement in renal tubular disease patients has only been considered recently.

METHODS

We screened 71 papers (including experimental research, clinical research, etc.) about Dent's disease, Gitelman syndrome, and cystinosis from PubMed, and made reference.

RESULTS

Glomerular disease was initially underestimated among the clinical signs of renal tubular disease or was treated merely as a consequence of the tubular damage. Renal tubular diseases affect glomerular podocytes through certain mechanisms resulting in functional damage, morphological changes, and glomerular lesions.

CONCLUSIONS

This article focuses on the progress of changes in glomerular podocyte function in Dent disease, Gitelman syndrome, and cystinosis for the purposes of facilitating clinically accurate diagnosis and scientific treatment and improving prognosis.