Dent's disease: An unusual cause of kidney failure.

Dent's disease is an X-linked recessive disease characterized by proximal tubulopathy with low-molecular weight proteinuria, hypercalciuria, nephrolithiasis, nephrocalcinosis, and kidney failure. It is mainly caused by mutations in the CLCN5 or OCRL1 genes, and only ~ 250 families have been identified with these mutations. We present a 31-year-old male referred to a nephrology consultation due to elevated serum creatinine and a history of nephrolithiasis. Complementary evaluation revealed protein/creatinine ratio of 1.9 g/g and albumin/creatinine ratio of 0.5 g/g, hypercalciuria and medullary nephrocalcinosis. These findings raised the suspicion of Dent's disease, which was confirmed by genetic testing. A missense mutation in the CLCN5 gene (c.810C>G, p.(Ser270Arg)), not previously reported in populational databases, was identified. During the evaluation of the patient, it came to our attention that a first-degree male cousin was being followed in our kidney transplantation unit. Given the unknown etiology of his chronic kidney disease, genetic testing was performed, identifying the same mutation. This case highlights the importance of considering the diagnosis of Dent's disease in the setting of a male patient with chronic kidney disease of unknown etiology, low-molecular-weight proteinuria, hypercalciuria, and nephrocalcinosis. Despite progression to end-stage kidney failure in a significant portion of male patients, there are no reports of recurrence after kidney transplantation.

Novel SLC12A3 mutation in Gitelman syndrome.

Gitelman syndrome (GS) is an autosomal recessive disease characterised by the presence of hypokalaemic metabolic alkalosis with hypomagnesaemia and hypocalciuria. The prevalence of this disease is 1-10/40 000. GS is usually associated with mild and non-specific symptoms and many patients are only diagnosed in adulthood. The disease is caused by mutations in the SLC12A3 gene. We present the case of a 49-year-old man referred to a nephrology appointment due to persistent hypokalaemia and hypomagnesaemia. Complementary evaluation revealed hypokalaemia, hypomagnesaemia, metabolic alkalosis, hyperreninaemia, increased chloride and sodium urinary excretion, and reduced urinary calcium excretion. Renal function, remainder serum and urinary ionogram, and renal ultrasound were normal. A diagnosis of GS was established and confirmed with genetic testing which revealed a novel mutation in SLC12A3 (c.1072del, p.(Ala358Profs*12)). This novel mutation extends the spectrum of known SLC12A3 gene mutations and further supports the allelic heterogeneity of GS.

Tubulointerstitial nephritis and uveitis syndrome in a female adult.

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare disease characterised by the association of acutetubulointerstitial nephritis and uveitis. It affects mainly children and young women. Drugs and infections may be precipitating factors. It is a diagnosis of exclusion. The mainstays of treatment are topical and systemic corticosteroids. Prognosis is usually favourable. We report a case of TINU which occurred in our unit. A 37-year-old woman presented with an influenza-like illness, bilateral ocular pain and blurred vision. Ophthalmological evaluation revealed bilateral anterior uveitis and later renal involvement was seen as acute tubulointerstitial nephritis. A diagnosis of TINU was assumed after exclusion of other systemic diseases. She was treated with topical corticosteroids for the uveitis and evolved favourably, with resolution of ocular symptoms and normalisation of serum creatinine and proteinuria. This case highlights the importance of a high degree of clinical suspicion to make the diagnosis of TINU syndrome.

Chryseobacterium indologenes peritonitis in a peritoneal dialysis patient.

Peritonitis remains an important complication of peritoneal dialysis. The Gram-negative bacillus Chryseobacterium indologenes causes infection mostly in immunocompromised patients with severe underlying disease, mainly in Asia. Herein, we report the first case in Europe and the second case in an immunocompetent patient of peritoneal dialysis-associated C. indologenes peritonitis. Our patient presented with abdominal pain and a cloudy effluent and was started on intraperitoneal antibiotics. The organism cultured from the peritoneal fluid was later identified as C. indologenes and antibiotic therapy was adjusted accordingly. Despite this, the peritonitis followed a relapsing course, requiring Tenckhoff catheter removal, temporary transfer to haemodialysis and intravenous antibiotics. Subsequently, a new Tenckhoff catheter was inserted and peritoneal dialysis was restarted. The patient remains peritonitis free after 18 months of follow-up. This case highlights the need to consider rare causes of peritonitis in peritoneal dialysis patients as well as the heterogeneous clinical course of C. indologenes peritonitis.