Diagnosis and treatment of Dent disease in 10 Chinese boys.
ABSTRACT: Dent disease is a rare X-linked recessive proximal tubular disorder that affects mostly male patients in childhood or early adult life. Dent disease is clinically characterized by the presence of low molecular weight proteinuria (LMWP), hypercalciuria, medullary nephrocalcinosis, nephrolithiasis, and progressive renal failure. The clinical features, diagnosis, and treatment of Dent disease were examined in 10 Chinese boys. All 10 childhood cases of Dent disease in China presented with tubular proteinuria in the nephrotic range and hypercalciuria. The ratio of ?1-microglobulinuria to microalbuminuria, if close to or above 1, can be used as a diagnostic criterion for tubuloproteinuria. Lotensin was ineffective at treating proteinuria while dihydrochlorothiazide reduced urine calcium excretion.
Project description:Dent disease is a rare X-linked renal proximal tubulopathy presenting with low-molecular-weight proteinuria (LMWP), hypercalciuria, and nephrocalcinosis, other signs of incomplete renal Fanconi syndrome, and renal failure. Early identification of patients who harbor disease-associated mutations is important for effective medical care and avoidance of unnecessary interventions. We report the case of an asymptomatic 9-year-old boy who presented with proteinuria in routine examination. Further investigation revealed the presence of nephrotic range proteinuria, mostly LMWP and mild hypercalciuria without nephrocalcinosis, or other features of tubular dysfunction. Renal function, growth, and bone mineral density were within regular limits. The male gender and the presence of LMWP and hypercalciuria even in the absence of other findings prompted us to genetic investigation for Dent disease. A novel splice site mutation (c.416-2A?>?G) of the chloride voltage-gated channel 5 ( <i>CLCN5</i> ) gene, responsible for Dent disease type 1 was identified. <i>In silico</i> analysis revealed that this mutation interferes with the mating of exons 4 and 5. Due to early molecular diagnosis, our patient did not undergo a renal biopsy, neither required aggressive pharmacological interventions. This case underscores the diversity and complexity of <i>CLCN5</i> mutations and highlights the importance of early molecular testing in male patients with incomplete phenotype of Dent disease.
Project description:Dent disease is an X-linked recessive proximal tubular disorder that affects mostly male patients in childhood or early adult life, caused by mutations in CLCN5 (Dent disease 1) or OCRL (Dent disease 2) genes, respectively. It presents mainly with hypercalciuria, low-molecular-weight proteinuria, nephrocalcinosis and progressive renal failure. We report here the same CLCN5 mutation but different phenotypes in two Chinese brothers, and speculate on the possible reasons for the variability of the genotype-phenotype correlations.
Project description:Dent disease (DD) is a rare X-linked recessive renal tubulopathy characterised by low-molecular-weight proteinuria (LMWP), hypercalciuria, nephrocalcinosis and/or nephrolithiasis. DD is caused by mutations in both the CLCN5 and OCRL genes. CLCN5 encodes the electrogenic chloride/proton exchanger ClC-5 which is involved in the tubular reabsorption of albumin and LMW proteins, OCRL encodes the inositol polyphosphate 5-phosphatase, and was initially associated with Lowe syndrome. In approximately 25 % of patients, no CLCN5 and OCRL mutations were detected. The aim of our study was to evaluate whether calcium phosphate metabolism disorders and their clinical complications are differently distributed among DD patients with and without CLCN5 mutations. Sixty-four male subjects were studied and classified into three groups: Group I (with CLCN5 mutations), Group II (without CLCN5 mutations) and Group III (family members with the same CLCN5 mutation). LMWP, hypercalciuria and phosphaturic tubulopathy and the consequent clinical complications nephrocalcinosis, nephrolithiasis, bone disorders, and chronic kidney disease (CKD) were considered present or absent in each patient. We found that the distribution of nephrolithiasis, bone disorders and CKD differs among patients with and without CLCN5 mutations. Only in patients harbouring CLCN5 mutations was age-independent nephrolithiasis associated with hypercalciuria, suggesting that nephrolithiasis is linked to altered proximal tubular function caused by a loss of ClC-5 function, in agreement with ClC-5 KO animal models. Similarly, only in patients harbouring CLCN5 mutations was age-independent kidney failure associated with nephrocalcinosis, suggesting that kidney failure is the consequence of a ClC-5 dysfunction, as in ClC-5 KO animal models. Bone disorders are a relevant feature of DD phenotype, as patients were mainly young males and this complication occurred independently of age. The triad of symptoms, LMWP, hypercalciuria, and nephrocalcinosis, was present in almost all patients with CLCN5 mutations but not in those without CLCN5 mutations. This lack of homogeneity of clinical manifestations suggests that the difference in phenotypes between the two groups might reflect different pathophysiological mechanisms, probably depending on the diverse genes involved. Overall, our results might suggest that in patients without CLCN5 mutations several genes instead of the prospected third DD underpin patients' phenotypes.
Project description:This review examines calcium and phosphate transport in the kidney through the lens of the rare X-linked genetic disorder Dent disease. Dent disease type 1 (DD1) is caused by mutations in the CLCN5 gene encoding ClC-5, a Cl- /H+ antiporter localized to early endosomes of the proximal tubule (PT). Phenotypic features commonly include low molecular weight proteinuria (LMWP), hypercalciuria, focal global sclerosis and chronic kidney disease; calcium nephrolithiasis, nephrocalcinosis and hypophosphatemic rickets are less commonly observed. Although it is not surprising that abnormal endosomal function and recycling in the PT could result in LMWP, it is less clear how ClC-5 dysfunction disturbs calcium and phosphate metabolism. It is known that the majority of calcium and phosphate transport occurs in PT cells, and PT endocytosis is essential for calcium and phosphorus reabsorption in this nephron segment. Evidence from ClC-5 KO models suggests that ClC-5 mediates parathormone endocytosis from tubular fluid. In addition, ClC-5 dysfunction alters expression of the sodium/proton exchanger NHE3 on the PT apical surface thus altering transcellular sodium movement and hence paracellular calcium reabsorption. A potential role for NHE3 dysfunction in the DD1 phenotype has never been investigated, either in DD models or in patients with DD1, even though patients with DD1 exhibit renal sodium and potassium wasting, especially when exposed to even a low dose of thiazide diuretic. Thus, insights from the rare disease DD1 may inform possible underlying mechanisms for the phenotype of hypercalciuria and idiopathic calcium stones.
Project description:Dent disease 1 is a rare X-linked recessive inherited disease, caused by pathogenic variants in the chloride voltage-gated channel 5 (CLCN5) gene. Dent disease 1 is characterized by low molecular weight (LMW) proteinuria, hypercalciuria, nephrocalcinosis, and chronic kidney disease. Infants may manifest only asymptomatic LMW proteinuria, which increases the difficulty of early diagnosis. We describe two male infants presenting only with nephrotic-range LMW proteinuria observed on examination using urine protein electrophoresis. Hereditary renal tubular diseases were highly suspected based on early onset age and LMW proteinuria. Thus, next-generation sequencing (NGS) was performed and pathogenic mutations in CLCN5 were identified in both patients. A diagnosis of Dent disease 1 was established based on the above informations. The two patients developed hypercalciuria during late follow-up, which verified the diagnosis. These two cases highlight the importance of next-generation sequencing in the early diagnosis of Dent disease 1 with only LMW proteinuria.
Project description:Dent disease-1 is a rare X-linked recessive renal tubular disorder caused by pathogenic variants in the chloride voltage-gated channel 5 (CLCN5) gene. It is characterized by low-molecular-weight proteinuria, hypercalciuria, nephrocalcinosis, nephrolithiasis and progressive renal failure. This is the first report of a CLCN5 pathogenic variant in a Dent disease-1 family of Sri Lankan origin, and it highlights the value of genetic evaluation in children with refractory proteinuria.A 2-year-old boy with non-nephrotic range proteinuria was referred for evaluation. His maternally related 24-year-old uncle had been investigated for similar features at the age of 14 years and his renal histology had shown few sclerosed glomeruli. He remained asymptomatic apart from proteinuria. Biochemical investigation of the child showed ?-2 microglobulinuria and hypercalciuria. After providing pre-test counseling and obtaining written informed consent, the child, his mother and maternal uncle underwent genetic testing for confirmation of the clinically suspected diagnosis of Dent disease-1. Both the child and his maternal uncle were found to be hemizygous for a nonsense pathogenic variant in exon 9 of the CLCN5 gene [NM_000084.4; c.1399C>T; rs797044811] which results in a stop codon at residue 467, leading to a truncated non-functional protein [NP_000075.1; p.R467X]. His mother was confirmed to be an unaffected heterozygous carrier for the same variant. Following confirmation of the diagnosis our patient was started on thiazide diuretics and potassium citrate.Even though the typical phenotype of Dent disease-1 often enables a clinical diagnosis to be made, less severe sub-clinical cases may go undiagnosed. The underlying diagnosis may be missed especially in children who are treated for non-minimal change nephrotic syndrome with steroids. This case highlights the need for tubular proteinuria to be considered in the differential diagnosis of children with refractory proteinuria and for appropriate genetic evaluation to be done to confirm the precise underlying diagnosis in such cases.
Project description:Dent disease is an X-linked recessive renal tubular disorder characterized by proximal tubule dysfunction. Typical features include low molecular weight proteinuria, hypercalciuria, nephrocalcinosis, nephrolithiasis, rickets, and chronic renal failure. We present a case of a 6-year-old boy with nephrotic proteinuria without hypoalbuminemia or edema. His renal biopsy revealed focal segmental glomerulosclerosis (FSGS), some of the glomeruli were globally sclerotic. Hypercalciuria was present intermittently and urine protein electrophoresis showed low molecular weight protein fraction of 50%. The next generation sequencing identified pathogenic variant in OCRL gene causing Dent disease type 2. We report an uncommon histologic finding of FSGS in Dent disease type 2 and highlight the importance of protein content examination and genetic analysis for the proper diagnosis in these complicated cases.
Project description:UNLABELLED:Dent disease is a rare X-linked tubulopathy with low molecular weight proteinuria, hypercalciuria, nephrolithiasis, nephrocalcinosis and progressive renal failure. We describe the case of a 9-year-old boy who presented with nephrotic-range albuminuria at the age of 3 years. In the absence of a clear diagnosis, a renal biopsy was performed at 4 years, which revealed minimal change disease. Due to the presence of low molecular weight proteinuria, even in the absence of hypercalciuria, a diagnosis of Dent disease was considered. While there were no mutations in the CLCN5 gene, the diagnosis was confirmed by the presence of a missense mutation (p.Arg318Cys) in the OCRL gene. CONCLUSION:Given the large phenotypic variability of the disease and based on our experience, we believe that children with low molecular weight proteinuria, even without hypercalciuria, should be investigated for Dent disease.
Project description:Dent disease is an inherited proximal renal tubulopathy leading to low molecular weight proteinuria, hypercalciuria with nephrocalcinosis and nephrolithiasis, and progressive renal failure. Two genetic mutations have been identified. The disease usually presents in childhood or early adult life and may be associated with other proximal tubular defects, which can lead to significant morbidity, especially in children. The disorder can extend to interstitial and glomerular cells, which contributes to progression to end-stage kidney disease. The pathophysiologic process remains incompletely understood, and no specific treatment is available. Dent disease is likely under-recognized. It needs to be included in the differential, especially in young males, presenting with recurrent kidney stones, proteinuria, and impaired renal function.
Project description:Whole exome sequencing detected novel likely pathogenic variants in LRP2 gene in 2 patients presenting with hearing and vision loss, and the Dent disease (DD) classical renal phenotype, that is, low molecular weight proteinuria (LMWP), hypercalciuria and nephrocalcinosis/nephrolithiasis. We propose that a subset of patients presenting as DD may represent unrecognized cases or mild forms of Donnai-Barrow/facio-oculo-acustico-renal (DB/FOAR) syndrome or be on the phenotypic continuum between the 2 conditions.