Genetic, Genomic and Epigenomic Studies of Balkan Endemic Nephropathy (Ben).

BEN is a primary, chronic tubulointerstitial nephritis characterized with chronic anemia, absence of edema, xantoderma, normal blood pressure and normal findings on the fundus oculi. The disease is distributed in restricted areas in Bulgaria, Romania, Croatia, Bosnia, Former Yugoslavia. Despite numerous studies on genetic and environmental factors and their possible involvement in BEN, its etiopathogenesis still remains elusive. Our recent study aim to elucidate the possible epigenetic component in BEN development. Whole genome DNA array methylation analysis was applied to compare the methylation profiles of male and female BEN patients from endemic regions in Bulgaria and Serbia and healthy controls. All three most prominent candidate genes with aberrations in the epigenetic profile discovered with this study are involved in the inflammatory/immune processes and oncogenesis. These data are in concordance with the reported pathological alterations in BEN. This research supports the role of epigenetic changes in BEN pathology. Exome sequencing of 22.000 genes with Illumina Nextera Exome Enrichment Kit revealed three mutant genes (CELA1, HSPG2, and KCNK5) in BEN patients which 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.

Genome-wide methylation profiling of schizophrenia.

Schizophrenia is one of the major psychiatric disorders. It is a disorder of complex inheritance, involving both heritable and environmental factors. DNA methylation is an inheritable epigenetic modification that stably alters gene expression. We reasoned that genetic modifications that are a result of environmental stimuli could also make a contribution. We have performed 26 high-resolution genome-wide methylation array analyses to determine the methylation status of 27,627 CpG islands and compared the data between patients and healthy controls. Methylation profiles of DNAs were analyzed in six pools: 220 schizophrenia patients; 220 age-matched healthy controls; 110 female schizophrenia patients; 110 age-matched healthy females; 110 male schizophrenia patients; 110 age-matched healthy males. We also investigated the methylation status of 20 individual patient DNA samples (eight females and 12 males. We found significant differences in the methylation profile between schizophrenia and control DNA pools. We found new candidate genes that principally participate in apoptosis, synaptic transmission and nervous system development (GABRA2, LIN7B, CASP3). Methylation profiles differed between the genders. In females, the most important genes participate in apoptosis and synaptic transmission (XIAP, GABRD, OXT, KRT7), whereas in the males, the implicated genes in the molecular pathology of the disease were DHX37, MAP2K2, FNDC4 and GIPC1. Data from the individual methylation analyses confirmed, the gender-specific pools results. Our data revealed major differences in methylation profiles between schizophrenia patients and controls and between male and female patients. The dysregulated activity of the candidate genes could play a role in schizophrenia pathogenesis.

[Genomic study in patients with idiopathic azoospermia and oligoasthenoteratozoospermia].

Genome disbalances are related to the different types of infertility and they play a role in the treatment of human infertility. Comparative genome hybridization (CGH) combined with microchips is a modern high resolution technique for all human chromosomes investigations. We analysed the genome disbalances in 16 blood samples of men with an idiopathic oligoastenozoospermia or azoospermia using CGH and microchips for the whole human genome. Our data showed a few affected loci, including: 3q26.32 deletion accompanied by 14q11.1 deletion, 9q12 deletion, 5q35.1 amplification, 7p22.3 amplification and 17q12-17q21.2 amplification. In this study we have match the deletions: in two patients in the same area in the 8 chromosome, as well as in 5 patients in 14 chromosome. The deleted region contains 25 genes. Two of them (SPAG11B and SPAG11A) are associated with stages of spermatogenesis and in particular formation and maturation of the spermatozoa. These genes play a role during spermatogenesis and fertilization. Loss. chr.14q11.2 (EDDM3A and EDDM3B) affected the proteins that are synthesized and secreted by epididymal epithelial cells that has been found up-regulated in epididimis of nonobstructive azoospermic men. Our results displayed the significance of CGH and microchip analysis as a promising area of research with serious clinical application for resolving the problems of the male infertility and still have an important annex for selecting the most appropriate methods for the treatment in these patients as a perspective scientific field of investigations with a clinical appliance.

Analysis of the genes encoding neuroligins NLGN3 and NLGN4 in Bulgarian patients with autism.

Many studies have supported a genetic aetiology for autism. Neuroligins are postsynaptically located cell-adhesion molecules. Mutations in two X-linked neuroligin genes, NLGN3 and NLGN4, have been implicated in pathogenesis of autism. In order to confirm these causative mutations in our autistic population and to determine their frequency we screened 20 individuals affected with autism. We identified one patient with a point mutation in NLGN4 gene that substituted a Met for Thr 787 - c.2360C > T, p.(Thr787Met) and three patients with identical polymorphisms in the same gene: c.933C > T, p.(Thr311Thr) in combination with c.[1777C > T+1779C > G, p.(Leu593Leu)]. All patients tested for NLGN3 mutations were negative. These results indicate that mutations in these genes are responsible for at most a small fraction of autism cases.