Balkan Endemic Nephropathy (BEN) is a kidney disease that progresses slowly. Only a few studies have investigated renal clinical markers in offspring of BEN families before the onset of the disease. This project aimed to determine whether kidney function and structure are altered in BEN offspring compared with non-BEN offspring. The study population consisted of 102 adult BEN offspring and a control group of 99 non-BEN offspring. We collected urine and blood samples, and conducted face-to-face interviews, physical examinations and ultrasound measurements of the kidney. Total protein, albumin, beta2-microglobulin and creatinine in urine, creatinine and urea in serum, and creatinine clearance (CCR) were determined. Two risk factors were assessed: first, the overall status of being an offspring from a BEN family, and second, the specific status of a mother and/or father with BEN. The data were analyzed using linear regression. After adjusting for confounders, we found that kidney length and minimal cortex width in BEN offspring were significantly decreased. Urine concentrations of total protein, albumin, and beta2-microglobulin were higher in BEN offspring. Regarding parental history, the associations were statistically significant only for the offspring of mothers who had BEN, with the exception of minimal cortex width, which showed no parental difference. For CCR, we did not identify a statistically significant effect for BEN offspring status nor for parental history. In conclusion, adult offspring of BEN families can be characterized by shorter kidney length and an increased excretion of albumin, total protein, and beta2-microglobulin, in particular, when the mother had BEN.

Balkan endemic nephropathy (BEN) is a familial chronic tubulointerstitial disease with insidious onset and slow progression leading to terminal renal failure. The results of molecular biological investigations propose that BEN is a multifactorial disease with genetic predisposition to environmental risk agents. Exome sequencing of 22 000 genes with Illumina Nextera Exome Enrichment Kit was performed on 22 DNA samples (11 Bulgarian patients and 11 Serbian patients). Software analysis was performed via NextGene, Provean, and PolyPhen. The frequency of all annotated genetic variants with deleterious/damaging effect was compared with those of European populations. Then we focused on nonannotated variants (with no data available about them and not found in healthy Bulgarian controls). There is no statistically significant difference between annotated variants in BEN patients and European populations. From nonannotated variants with more than 40% frequency in both patients' groups, we nominated 3 genes with possible deleterious/damaging variants—CELA1, HSPG2, and KCNK5. Mutant genes (CELA1, HSPG2, and KCNK5) in BEN patients encode proteins involved in basement membrane/extracellular matrix and vascular tone, tightly connected to process of angiogenesis. We suggest that an abnormal process of angiogenesis plays a key role in the molecular pathogenesis of BEN.

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BackgroundDespite the characteristic extensive tubulointerstitial fibrosis, Balkan Endemic Nephropathy (BEN) is usually considered a non-inflammatory disease.MethodsWe examined a marker of inflammation, C-reactive protein (CRP), in the offspring of patients with BEN, a population at risk for BEN, prior to development of established disease to determine if an inflammatory process could be identified in the early stages of the disease. In 2003/04, 102 adult offspring whose parents had BEN and a control group of 99 adult offspring of non-BEN patients were enrolled in this prospective study. This cohort was re-examined yearly for four consecutive years. Levels of serum CRP were measured in years 3 and 4 and compared between groups. The data were analyzed with mixed models.ResultsCompared to controls, offspring of BEN parents had statistically higher CRP levels in two consecutive years, suggestive of early inflammatory reactivity. Whenever the mother was affected by BEN (both parents, or mother only), serum CRP was significantly increased, but not if only the father had BEN. CRP was inversely related to kidney cortex width but not to markers or renal function.ConclusionEarly stages of BEN may involve inflammatory processes. The observation of a maternal involvement supports the concept of fetal programming, which has been implicated in the pathogenesis of other chronic kidney diseases.

BackgroundBalkan endemic nephropathy (BEN) represents a chronic progressive interstitial nephritis in striking correlation with uroepithelial tumours of the upper urinary tract. The disease has endemic distribution in the Danube river regions in several Balkan countries.DNA methylation is a primary epigenetic modification that is involved in major processes such as cancer, genomic imprinting, gene silencing, etc. The significance of CpG island methylation status in normal development, cell differentiation and gene expression is widely recognized, although still stays poorly understood.MethodsWe performed whole genome DNA methylation array analysis on DNA pool samples from peripheral blood from 159 affected individuals and 170 healthy individuals. This technique allowed us to determine the methylation status of 27 627 CpG islands throughout the whole genome in healthy controls and BEN patients. Thus we obtained the methylation profile of BEN patients from Bulgarian and Serbian endemic regions.ResultsUsing specifically developed software we compared the methylation profiles of BEN patients and corresponding controls and revealed the differently methylated regions. We then compared the DMRs between all patient-control pairs to determine common changes in the epigenetic profiles.SEC61G, IL17RA, HDAC11 proved to be differently methylated throughout all patient-control pairs. The CpG islands of all 3 genes were hypomethylated compared to controls. This suggests that dysregulation of these genes involved in immunological response could be a common mechanism in BEN pathogenesis in both endemic regions and in both genders.ConclusionOur data propose a new hypothesis that immunologic dysregulation has a place in BEN etiopathogenesis.