Effective immunosuppressive management with belatacept and eculizumab in post-transplant aHUS due to a homozygous deletion of CFHR1/CFHR3 and the presence of CFH antibodies.

Atypical haemolytic uraemic syndrome (aHUS) may clinically present as acute renal graft failure resulting from excessive activation of the complement cascade. While mutations of complement-encoding genes predispose for aHUS, it is generally thought to require an additional insult (e.g. drugs) to trigger and manifest the full-blown clinical syndrome. Calcineurin inhibitors (CNIs) used for immunosuppression act as potential triggers, especially in the post-transplantation setting. Therefore, CNI-free immunosuppressive regimens may be beneficial. We report on a 58-year-old woman who developed aHUS with acute graft failure within 20 days after renal transplantation. Genetic investigation revealed a homozygous deletion of the CFH-related 1 (CFHR1) and CFHR3 genes in addition to the presence of autoantibodies against complement factor H (CFH). The patient was treated with plasmapheresis and administration of the complement component 5 (C5) antibody eculizumab, and her immunosuppressive regimen was switched from CNI (tacrolimus) to the cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitor belatacept. Renal graft function recovered and stabilized over an 18-month follow-up period. We describe the successful management of post-transplant aHUS using a CNI-free immunosuppressive regimen based on eculizumab and belatacept. Ideally, adequate molecular diagnostics, performed prior to transplantation, can identify relevant genetic risk factors for graft failure and help to select patients for individualized immunosuppressive regimens.

Autochthonous Dobrava-Belgrade virus infection in Eastern Germany.

A 21-year-old male patient from Borna, Saxony, in Eastern Germany, suffered from acute kidney injury (AKI) and symptoms typical for a hantavirus infection. These symptoms included nausea, vomiting, abdominal pain, diarrhea, and acute renal failure. Serological investigations by indirect IgM and IgG in-house ELISAs, commercial immunofluorescence and line assays, as well as chemiluminescence focus reduction neutralization assay confirmed an acute Dobrava-Belgrade virus (DOBV) infection of the patient. Serological and RT-PCR analyses of striped field mouse (Apodemus agrarius) trapped in a neighboring region of the residence of the patient identified an infection by DOBV, genotype Kurkino. This is the first report of an autochthonous DOBV infection in a German patient living far from the known endemic region in the north of the country. This finding has implications for the awareness of physicians in areas which are not recognized as hantavirus endemic regions but where the reservoir host of the virus is present.

Isolated renal relapse of sarcoidosis under low-dose glucocorticoid therapy.

Sarcoidosis is a multisystem disease of unknown etiology. Renal manifestation is rare and usually caused by hypercalcemia and nephrocalcinosis. Moreover, renal disease can occur as granulomatous interstitial nephritis (GIN), which is a histological diagnosis. We describe a case of sarcoidosis first presenting with multiple organ involvement including renal failure caused by severe GIN and subsequent remission on glucocorticoid therapy. After 18 months under low-dose prednisolone, the patient was readmitted with acute renal failure, histologically confirmed to be a relapse of renal sarcoidosis. Extrarenal manifestations of sarcoidosis were not present. Glucocorticoid dose was raised and kidney function again recovered significantly. Usual serologic markers of disease activity were not appropriate to indicate disease activity. Renal manifestation of sarcoidosis should be diagnosed by renal biopsy to guide therapy and probably requires larger glucocorticoid doses and prolonged treatment to prevent relapse.

Phenotype of a patient with a de novo mutation in the hepatocyte nuclear factor 1beta/maturity-onset diabetes of the young type 5 gene.

Mutations in the gene encoding the transcription factor hepatocyte nuclear factor (HNF) 1beta cause various phenotypes including maturity-onset diabetes of the young type 5 (MODY5) and kidney disease. We provide molecular and pathophysiologic characterization of a 23-year-old male patient with clinical presentation typical for MODY5 with renal involvement. Clinical studies (including intravenous glucose tolerance test and magnetic resonance imaging) of the patient and 5 family members in comparison with unrelated control subjects and molecular analysis of the HNF-1beta gene (direct sequencing, paternity testing, and restriction fragment length polymorphism analysis for parental mosaicism) were performed. The patient was born with low birth weight (2250 g), whereas his dizygotic twin sister was of normal weight (3500 g) and healthy. He had cystic renal dysplasia with progressive renal failure and pancreas atrophy with beta-cell dysfunction and early-onset diabetes mellitus but no family history of diabetes. Intravenous glucose tolerance test showed a markedly reduced but not absent acute insulin response compared with controls (n = 6). A mutation in the HNF-1beta gene S148L (C443T) in exon 2 within the pseudo-POU domain was identified. All other family members and the control group (n = 255) did not have the mutation, suggesting that we described a de novo mutation in HNF-1beta. Paternity was confirmed, and no signs of mosaicism in DNA analysis of both parents could be detected. Of note, the low birth weight of the patient in contrast to his healthy twin sister provides interesting support for the fetal insulin hypothesis for reduced birth weight.

Oral antidiabetic agents: how much kidney disease can we tolerate?

Type 2 diabetes mellitus and chronic kidney disease in mild and moderate stages is a common and underestimated comorbidity with relevant therapeutic consequences. Available oral antidiabetic agents are effectively used in keeping blood glucose levels within the guideline range but long lists of contraindications often limit their use. Chronic kidney disease is a very common reason to withhold or discontinue an oral antidiabetic therapy, precluding many patients from drugs with proven benefit, such as metformin. Often contraindications are not based on data but on theoretical grounds or expert opinion. In this review, we critically review threshold levels of kidney function for common oral antidiabetic agents, the evidence from which they were derived and offer advice on how to monitor kidney function as an important procedure in clinical practice.