Focal segmental glomerulosclerosis in association with Gitelman syndrome

Clinicopathological Features of Gitelman Syndrome with Proteinuria and Renal Dysfunction

INTRODUCTION

Gitelman syndrome (GS) is a rare renal tubular salt-wasting disorder. Besides kidney electrolyte loss, proteinuria and renal dysfunction were also observed. However, their incidence, risk factors, pathological features, and prognosis were unclear.

METHODS

We retrospectively reviewed 116 GS patients and analyzed their clinical, genetic, and pathological characteristics. We also systematically reviewed articles on GS with proteinuria and renal dysfunction.

RESULTS

Twenty-three GS patients had proteinuria (69.6%) and renal dysfunction (43.5%) with a mean age of 35.3 ± 13.2 years, and 65.2% were male. Compared to patients without proteinuria or renal dysfunction, these patients had elevated plasma angiotensin II level (440.2 ± 351.7 vs. 253.2 ± 187.4 pg/mL, p = 0.031) and three times higher incidence of diabetes. The renal pathology of nine biopsied patients indicated hypertrophy of the juxtaglomerular apparatus (100%), chronic tubulointerstitial changes (66.7%), intrarenal vascular changes (66.7%), and glomerulopathy (55.6%). More extensive renin staining was observed in patients with GS than in the control group with glomerular minor lesion (p < 0.001). During a median of 85 months (range, 11-205 months) of follow-up for 19 out of the 23 GS-renal patients, the renal function was generally stable, except one died of cancer and one developed end-stage renal disease because of concomitant membranous nephropathy and IgA nephropathy.

CONCLUSION

Proteinuria and renal dysfunction were more common than expected and might indicate glomerulopathy and vascular lesions besides a tubulointerstitial injury in GS. Renal function may maintain stable with effective therapy in most cases.

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.

A case of Gitelman syndrome with membranous nephropathy

Background

Gitelman syndrome (GS) is a rare autosomal recessive inherited salt-losing tubulopathy (SLT). Here, we report, for the first time, a case of GS overlapping nephrotic syndrome (NS) related to PLA2R-associated membranous nephropathy (MN).

Case presentation

We described a male patient had a 4-year history of recurrent fatigue. Serum biochemistry revealed hypokalemia with renal potassium wasting, hypomagnesemia, metabolic alkalosis, hyperreninemia, hypocalciuria, as well as nephrotic-range proteinuria, hypoalbuminemia, and elevated serum anti-phospholipase A2 receptor (PLA2R) antibody. Gene sequencing identified compound heterozygous mutations in SLC12A3 [c.536T > A(p.V179D) and c.1456G > A(p.D486N)]. The unusual association of SLTs and nephrotic-range glomerular proteinuria prompted us to perform a renal biopsy. Renal biopsy showed idiopathic MN. Due to the potential to activate the sodium-chloride co-transporter (NCC) and cause hyperkalemia, tacrolimus was selected to treat NS. Following treatment with potassium chloride, magnesium oxide, low-dose glucocorticoid combined with tacrolimus, the fatigue significantly improved, and concurrently hypokalemia, hypomagnesemia were corrected and NS was remitted.

Conclusions

Renal biopsy should be warranted for GS patients with moderate to nephrotic-range proteinuria. Tacrolimus was preferred to the management of GS patients with NS.

Gitelman Syndrome: A Rare Cause of Seizure Disorder and a Systematic Review

Gitelman syndrome is one of the few inherited causes of metabolic alkalosis due to salt losing tubulopathy. It is caused by tubular defects at the level of distal convoluted tubules, mimicking a thiazide-like tumor. It usually presents in late childhood or in teenage as nonspecific weakness, fatigability, polyuria, and polydipsia but very rarely with seizures. It is classically associated with hypokalemia, hypomagnesemia, hypocalciuria, hyperreninemia, and hyperaldosteronism. However, less frequently, it can present with normal magnesium levels. It is even rarer to find normomagnesemic patients of GS who develop seizures as the main complication since hypomagnesemia is considered the principal etiology of abnormal foci of seizure-related brain activity in GS cases. Interestingly, patients with GS are oftentimes diagnosed during pregnancy when the classic electrolyte pattern consistent with GS is noticed. Our case presents GS with normal serum magnesium in a patient, with seizures being the main clinical presentation. We also did a comprehensive literature review of 122 reported cases to show the prevalence of normal magnesium in GS cases and an overview of clinical and biochemical variability in GS. We suggest that further studies and in-depth analysis are required to understand the pathophysiology of seizures in GS patients with both normal and low magnesium levels.

A case of hypokalemia and proteinuria with a new mutation in the SLC12A3 Gene

Background

Gitelman syndrome is an autosomal recessive inherited renal disorder characterized by hypokalemia, hypomagnesemia, and hypocalciuria. Since the symptoms are not severe and laboratory results are not always clear, Gitelman syndrome can go unnoticed by physicians. Here, we report our experiences with a patient that presented with hypokalemia and proteinuria; genetic analysis revealed a new homozygous mutation in the SLC12A3 gene.

Case presentation

A 47-year-old man presented with hypokalemia and proteinuria. He had come to the hospital with the same symptoms 11 months and 3 years prior. His laboratory tests showed hypokalemia, hypocalciuria, and increased plasma angiotensin-2 activity. His renal pathology was consistent with the development of minimal lesions. Genetic analysis found a new homozygous mutation in exon 6 on the SLC12A3 gene (p.Trp281Arg) in the patient and in his brother; his mother and sister were diagnosed as heterozygous carriers of the same gene mutation. Finally, the patient was diagnosed with Gitelman syndrome.

Conclusions

This case is the first to report a homozygous mutation in the 841th nucleotide of exon 6 on the SLC12A3 gene (p.Trp281Arg), which may cause Gitelman syndrome. At the same time, this report might stimulate interest in discussing the relationship between different mutations in the SLC12A3 gene and renal pathology.

Fanconi syndrome and severe polyuria: an uncommon clinicobiological presentation of a Gitelman syndrome

BACKGROUND

Gitelman syndrome is an autosomal recessive tubulopathy characterized by hypokalemia, hypomagnesemia, metabolic alkalosis and hypocalciuria. The majority of patients do not present with symptoms until late childhood or adulthood, and the symptoms are generally mild. We report here the first case of Gitelman syndrome presenting with the biological features of Fanconi syndrome and an early polyuria since the neonatal period. We discuss in this article the atypical electrolytes losses found in our patient, as well as the possible mechanisms of severe polyuria.

CASE PRESENTATION

A 6-year-old Caucasian girl was admitted via the Emergency department for vomiting, and initial laboratory investigations found hyponatremia, hypokalemia, metabolic acidosis with normal anion gap, hypophosphatemia, and hypouricemia. Urinalysis revealed Na, K, Ph and uric acid losses. Thus, the initial biological profile was in favor of a proximal tubular defect. However, etiological investigations were inconclusive and the patient was discharged with potassium chloride and phosphorus supplementation. Three weeks later, further laboratory analysis indicated persistent hypokalemia, a metabolic alkalosis, hypomagnesemia, and hypocalciuria. We therefore sequenced the SLC12A3 gene and found a compound heterozygosity for 2 known missense mutations.

CONCLUSIONS

Gitelman syndrome can have varying and sometimes atypical presentations, and should be suspected in case of hypokalemic tubular disorders that do not belong to any obvious syndromic entity. In this case, the proximal tubular dysfunction could be secondary to the severe hypokalemia. This report emphasizes the need for clinicians to repeat laboratory tests in undiagnosed tubular disorders, especially not during decompensation episodes.