An infant with poor weight gain and hypochloremic metabolic alkalosis: a case report

Bartter Syndrome: A Systematic Review of Case Reports and Case Series

Background and Objectives: Bartter syndrome (BS) is a rare group of autosomal-recessive disorders that usually presents with hypokalemic metabolic alkalosis, occasionally with hyponatremia and hypochloremia. The clinical presentation of BS is heterogeneous, with a wide variety of genetic variants. The aim of this systematic review was to examine the available literature and provide an overview of the case reports and case series on BS. Materials and Methods: Case reports/series published from April 2012 to April 2022 were searched through Pubmed, JSTOR, Cochrane, ScienceDirect, and DOAJ. Subsequently, the information was extracted in order to characterize the clinical presentation, laboratory results, treatment options, and follow-up of the patients with BS. Results: Overall, 118 patients, 48 case reports, and 9 case series (n = 70) were identified. Out of these, the majority of patients were male (n = 68). A total of 21 patients were born from consanguineous marriages. Most cases were reported from Asia (73.72%) and Europe (15.25%). In total, 100 BS patients displayed the genetic variants, with most of these being reported as Type III (n = 59), followed by Type II (n = 19), Type I (n = 14), Type IV (n = 7), and only 1 as Type V. The most common symptoms included polyuria, polydipsia, vomiting, and dehydration. Some of the commonly used treatments were indomethacin, potassium chloride supplements, and spironolactone. The length of the follow-up time varied from 1 month to 14 years. Conclusions: Our systematic review was able to summarize the clinical characteristics, presentation, and treatment plans of BS patients. The findings from this review can be effectively applied in the diagnosis and patient management of individuals with BS, rendering it a valuable resource for nephrologists in their routine clinical practice.

Functional Study of Novel Bartter's Syndrome Mutations in ClC-Kb and Rescue by the Accessory Subunit Barttin Toward Personalized Medicine

Type III and IV Bartter syndromes (BS) are rare kidney tubulopathies caused by loss-of-function mutations in the CLCNKB and BSND genes coding respectively for the ClC-Kb chloride channels and accessory subunit barttin. ClC-K channels are expressed in the Henle's loop, distal convoluted tubule, and cortical collecting ducts of the kidney and contribute to chloride absorption and urine concentration. In our Italian cohort, we identified two new mutations in CLCNKB, G167V and G289R, in children affected by BS and previously reported genetic variants, A242E, a chimeric gene and the deletion of the whole CLCNKB. All the patients had hypokalemia and metabolic alkalosis, increased serum renin and aldosterone levels and were treated with a symptomatic therapy. In order to define the molecular mechanisms responsible for BS, we co-expressed ClC-Kb wild type and channels with point mutations with barttin in HEK 293 cells and characterized chloride currents through the patch-clamp technique. In addition, we attempted to revert the functional defect caused by BS mutations through barttin overexpression. G167V and A242E channels showed a drastic current reduction compared to wild type, likely suggesting compromised expression of mutant channels at the plasma membrane. Conversely, G289R channel was similar to wild type raising the doubt that an additional mutation in another gene or other mechanisms could account for the clinical phenotype. Interestingly, increasing ClC-K/barttin ratio augmented G167V and A242E mutants' chloride current amplitudes towards wild type levels. These results confirm a genotype-phenotype correlation in BS and represent a preliminary proof of concept that molecules functioning as molecular chaperones can restore channel function in expression-defective ClC-Kb mutants.

Bartter Syndrome Type 3: Phenotype-Genotype Correlation and Favorable Response to Ibuprofen

Objective: To investigate the phenotype-genotype correlation in different genetic kinds of Bartter syndrome type 3 in children. Methods: Clinical and genetic data of 2 patients with different mutations in Bartter syndrome type 3 was analyzed while the prognosis was compared after a 6-year follow-up or 2-year follow-up, respectively. Results: Bartter syndrome is a kind of autosomal recessive inherited renal disorder. The manifestation and prognosis of Bartter syndrome change with mutation types, and severe mutation were often accompanied with unfavorable prognosis. Comprehensive therapy with ibuprofen, antisterone, captopril, and potassium have remarkable effect, while ibuprofen may improve growth retardation partly. Conclusion: Bartter syndrome should be considered when children have unreasonable continuous electrolyte disturbance, metabolic alkalosis and growth retardation.As a genetic disease, its clinical features depend on the mutation type. It can be ameliorated by electrolyte supplementation, prostaglandin synthetase inhibitors, angiotensin-converting enzyme inhibitors and potassium-sparing diuretic. Considering the following electrolyte disturbances, infections, growth retardation, kidney failure and even death, Bartter syndrome need lifelong treatment, early diagnosis and treatment is the most important.

Renovascular hypertension: a case with atypical neurological signs

Secondary hypertension is the most frequent form of hypertension in children. Renovascular disease accounts for 5-10% of all childhood hypertension and should be suspected in the presence of severe hypertension found difficult to manage with medical therapy. Uncontrolled hypertension can lead to severe target organ damage. We describe the case of a 13-month-old baby boy with failure to thrive, recent muscular weakness of the lower extremities and irritability. Hypertension was detected and he was admitted to the paediatric intensive care unit with a refractory hypertensive emergency, despite multiple antihypertensive therapies. Bilateral renal artery stenosis was diagnosed through renal angiography and balloon dilation was performed, leading to lower blood pressure. He is currently withdrawing from antihypertensive medication, and slowly gaining weight and recovering from target organ damage. However, weakness of the lower extremities persists and he has been diagnosed with a neurogenic bladder.