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

Case report of atypical presentation of Bartter's syndrome: hypertension and Hypokalemic nephropathy in a female patient

Bartter's syndrome (BS) is a rare hereditary disorder characterized by tubulopathies that affect salt reabsorption in the thick ascending limb of the Henle's loop. While BS typically presents with electrolyte imbalances and normal blood pressure, atypical presentations can complicate its diagnosis and management. We report the case of a 21-year-old female with BS diagnosed clinically at birth who presented with cough, vomiting, and elevated blood pressure. Despite a positive family history of BS, her presentation was unique with hypertension and hypokalemic nephropathy. Diagnostic evaluations during hospital admission revealed electrolyte imbalances, kidney dysfunction, and renal histopathological findings that were consistent with hypokalemic nephropathy. This case highlights the diverse clinical manifestations and potential complications of BS and emphasizes the importance of thorough evaluation and multidisciplinary management. Further research is needed to elucidate the underlying mechanisms linking BS with hypertension and hypokalemic nephropathy, and to guide targeted therapeutic strategies for complex presentations.

Genomic abnormalities in apparently isolated polyhydramnios and the role of confirmed fetal phenotype: a systematic review and meta-analysis

OBJECTIVE

The aim of this systematic review and meta-analysis was to assess the rate of genomic abnormalities detected in pregnancies with apparently isolated hydramnios and to explore the role of confirmed fetal phenotype.

DATA SOURCES

The PubMed, Cochrane Library, Google Scholar, and Scopus databases were searched up to May 4, 2024.

STUDY ELIGIBILITY CRITERIA

Observational studies that were published after the year 2000, written in a European language, and that reported the genomic outcomes of pregnancies complicated by prenatally diagnosed isolated polyhydramnios were included in this meta-analysis.

METHODS

The main outcome was the incidence of genomic abnormalities, defined as chromosomal numerical or structural anomalies or monogenic syndromes, that were diagnosed prenatally or postnatally in neonates from pregnancies complicated by isolated polyhydramnios. Additional outcomes included the incidence of chromosomal abnormalities, including both numerical and structural aberrations of the chromosomes (detected by karyotype or chromosomal microarray), monogenic abnormalities (detected by next-generation sequencing or clinical genetic examination after the result of a normal karyotype or chromosomal microarray), genetic syndromes in general (diagnosed clinically with or without genetic confirmation), and structural abnormalities detected postnatally. Pooled proportions were calculated for each outcome.

RESULTS

A total of 12 studies (2561 pregnancies complicated by isolated hydramnios) were included in the meta-analysis. The pooled prevalence of genomic anomalies in fetuses with apparently isolated polyhydramnios (12 studies, 2634 fetuses) was 4.5% (95% confidence interval, 2.6-7.6). The pooled prevalence of chromosomal abnormalities (11 studies, 2427 fetuses) was 2.1% (95% confidence interval, 1.1-3.7). The proportion of major structural defects detected postnatally (9 studies, 1731 fetuses) was 2.9% (95% confidence interval, 1.5-5.4); in this particular subgroup (4 studies, 14 fetuses), the pooled prevalence of genomic anomalies was 29.8% (95% confidence interval, 11.3-58.6). A meta-regression analysis indicated that the rate of genomic anomalies was positively associated with the severity of hydramnios. In addition, the pooled rate of monogenic anomalies was 5.6% (95% confidence interval, 2-5; I2=58%) in the 2 studies that used next-generation sequencing for genomic diagnosis.

CONCLUSION

This meta-analysis showed that the rate of genomic anomalies in apparently isolated polyhydramnios is 4.5%; approximately half of them are chromosomal abnormalities and the other half are nonchromosomal genomic anomalies. From a clinical standpoint, chromosomal microarray analysis and possibly next-generation sequencing could be considered even in cases of apparently isolated polyhydramnios; this may be even more important in cases with incomplete fetal phenotype. Further studies using next-generation sequencing and addressing cost-effectiveness issues would fine-tune such recommendations.

An Unusual Presentation of Failure to Thrive in a Toddler: Bartter Syndrome

Bartter syndrome is a rare salt-wasting renal tubular disorder of autosomal-recessive inheritance. Antenatal Bartter syndrome (types I, II, and IV) manifests in infancy and has a more severe course compared to the classic Bartter syndrome (type III). This report details a unique instance of a male toddler, aged 18 months, who presented with failure to thrive, polydipsia, and polyuria. Blood gases revealed hypochloremic metabolic alkalosis with hyponatremia and hypokalemia. The diagnosis was confirmed by genetic testing, and the child was started on indomethacin and potassium supplementation. Despite being rare in children, this case report emphasizes the importance of looking beyond the usual in a child who presents with failure to thrive to prevent a delay in the diagnosis and treatment.

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.