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1.
SARS-CoV-2 molecular epidemiology in Slovenia, January to September 2021
Sandra Janežič, Aleksander Mahnič, Urška Kuhar, Jernej Kovač, Barbara Jenko Bizjan, Tom Koritnik, Tine Tesovnik, Robert Šket, Uroš Krapež, Brigita Slavec, Tadej Malovrh, Tadej Battelino, Maja Rupnik, Tjaša Žohar Čretnik, 2023, original scientific article

Abstract: Background: Sequencing of SARS-CoV-2 PCR-positive samples was introduced in Slovenia in January 2021. Our surveillance programme comprised three complementary schemes: (A) non-targeted sequencing of at least 10% of samples, (B) sequencing of samples positive after PCR screening for variants of concern (VOC) and (C) sequencing as per epidemiological indication. Aim: We present the analysis of cumulative data of the non-targeted surveillance of SARS-CoV-2 and variantdependent growth kinetics for the five most common variants in Slovenia for the first 9 months of 2021. Methods: SARS-CoV-2 PCR-positive samples, from January to September 2021, were selected for sequencing according to the national surveillance plan. Growth kinetics studies were done on Vero E6 cells. Results: Altogether 15,175 genomes were sequenced and 64 variants were detected, of which three successively prevailed. Variant B.1.258.17 was detected in ca 80% of samples in January and was replaced, within 9 weeks, by the Alpha variant. The number of cases decreased substantially during the summer of 2021. However, the introduction of the Delta variant caused a fourth wave and completely outcompeted other variants. Other VOC were only detected in small numbers. Infection of Vero E6 cells showed higher replication rates for the variants Alpha and Delta, compared with B.1.258.17, B.1.258, and B.1.1.70, which dominated in Slovenia before the introduction of the Alpha and Delta variants. Conclusion: Information on SARS-CoV-2 variant diversity provided context to the epidemiological data of PCR-positive cases, contributed to control of the initial spread of known VOC and influenced epidemiological measures.
Keywords: SARS-CoV-2, molecular epidemiology
Published in DiRROS: 31.08.2026; Views: 159; Downloads: 96
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2.
Transposable elements as a possible missing link between genetic predisposition and environmental triggers of autoimmune disorders : insights from type 1 diabetes, systemic lupus erythematosus and rheumatoid arthritis
Karolina Mužina, Ana Markež, Barbara Jenko Bizjan, Neja Šamec, Jernej Kovač, Klemen Dovč, Tadej Battelino, Marko Pokorn, 2026, review article

Abstract: Transposable elements (TEs) make up almost half of the human genome and are among its most densely methylated regions. Their epigenetic silencing is crucial for genomic stability and immune homeostasis, and accumulating evidence indicates that dysregulated TE methylation and expression contribute to autoimmune disease pathogenesis. Hypomethylation of selected TE families can permit transcriptional reactivation, production of immunostimulatory nucleic acids and peptides, and engagement of pattern-recognition receptors, thereby driving type I interferon (IFN-I) signaling through “viral mimicry”–like mechanisms. In parallel, TE-derived enhancers, promoters and exons reshape gene regulatory networks at immune loci. In this narrative review, we synthesize current knowledge on TE methylation and expression in autoimmunity, with a focus on type 1 diabetes (T1D), systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). We first outline TE biology and the principal mechanisms of epigenetic silencing, then summarise methodological advances for TE methylation and expression profiling, including long-read sequencing and TE-aware RNA-seq pipelines. We next dissect disease-specific evidence: longitudinal epigenomic studies in T1D showing preclinical DNA methylation changes and altered Alu/LINE-1 patterns, together with HERV-H/W upregulation at onset, SLE studies demonstrating LINE-1 hypomethylation in neutrophils and cell-type–specific TE overexpression that tracks with IFN signatures and nucleic acid sensor pathways, and RA studies linking global and LINE-1 methylation to methotrexate response when integrated with serostatus. Across conditions, TE methylation behaves more like a relatively stable disease-associated trait than a simple activity marker and exhibits clear disease- and cell-type-specific signatures rather than global hypomethylation. We conclude that TEs are not passive genomic relics but epigenetically regulated elements that can act as endogenous sources of immunostimulatory nucleic acids, neoantigens and regulatory sequences, providing a mechanistic bridge between genetic susceptibility and environmental triggers in autoimmunity. Consequently, selective dysregulation of TE methylation and expression offers both an explanatory framework for interferon-driven autoimmunity and a promising, currently underused layer for biomarker development and therapeutic targeting.
Keywords: RNA-seq, autoimmune disease, autoimmunity, epigenetic, methylation, sequencing, transposable elements
Published in DiRROS: 20.08.2026; Views: 198; Downloads: 166
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3.
Integrative transcriptomic profiling of the Wilms tumor
Simona Lucija Avčin, Klementina Črepinšek, Barbara Jenko Bizjan, Robert Šket, Jernej Kovač, Blaž Vrhovšek, Jerca Blazina, Olga Blatnik, Robert Kordič, Lidija Kitanovski, Janez Jazbec, Maruša Debeljak, Tine Tesovnik, 2023, original scientific article

Abstract: Our study aimed to identify relevant transcriptomic biomarkers for the Wilms tumor, the most common pediatric kidney cancer, independent of the histological type and stage. Using next-generation sequencing, we analyzed the miRNA profiles of 74 kidney samples, which were divided into two independent groups: fresh frozen tissue and formalin-fixed paraffin-embedded tissue samples. Subsequent mRNA expression profiling and pathway analysis were performed to establish the interplay and potential involvement of miRNAs and mRNA in the Wilms tumor. Comparative analysis, irrespective of post-dissection tissue processing, revealed 41 differentially expressed miRNAs, with 27 miRNAs having decreased expression and 14 miRNAs having increased expression in the Wilms tumor tissue compared to healthy kidney tissue. Among global mRNA transcriptomic profile differences, cross-sectional analysis suggested a limited list of genes potentially regulated by differentially expressed miRNAs in the Wilms tumor. This study identified the comprehensive miRNA and mRNA profile of the Wilms tumor using next-generation sequencing and bioinformatics approach, providing better insights into the pathogenesis of the Wilms tumor. The identified Wilms tumor miRNAs have potential as biomarkers for the diagnosis and treatment of the Wilms tumor, regardless of histological subtype and disease stage.
Keywords: Wilms tumor, NGS, miRNA profile, mRNA profile, universal biomarkers
Published in DiRROS: 06.08.2026; Views: 249; Downloads: 157
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4.
Genome-wide DNA methylation signatures in blood associated with pediatric obesity
Barbara Slapnik, Robert Šket, Blaž Vrhovšek, Primož Kotnik, Tadej Battelino, Jernej Kovač, 2026, original scientific article

Abstract: Background: Pediatric obesity is the most prevalent nutritional disorder in children and adolescents and is associated with multiple comorbidities. Understanding epigenetic mechanisms, particularly DNA methylation, offers potential for early risk prediction, prevention, and personalized interventions. In this study, genome-wide DNA methylation profiles in blood from children with obesity and matched controls were compared using Oxford Nanopore Technologies. Two independent analytical tools were applied to identify differentially methylated regions. Clinical data included family history, weight, BMI, and age at first examination. Participants with monogenic obesity, identified via short-read whole-exome sequencing, were excluded. Results: The cohort included five girls and five boys with obesity (median age 14.33, IQR 1.65; median BMI SDS 3.42, IQR 0.55) and matched controls (median age 13.94, IQR 0.52; median BMI SDS 0.26, IQR 1.71). Seven consensus differentially methylated regions were consistently identified, overlapping genes involved in metabolism and obesity-related comorbidities. Hypermethylation was observed in PM20D1, PM20D1-AS1, AC119673.2 (26.05% ± 0.78%), and GM2A (33.60% ± 1.10%) in children with obesity, primarily affecting metabolic and adipogenic pathways. Hypomethylation was detected in genes linked to obesity and its comorbidities, including S100A14, S100A16 (- 25.4% ± 0.48%), SNTG2 (- 25.55% ± 0.18%), ADARB2, LINC00200 (- 21.35% ± 0.98%), LRRC32, AP001189.1 (- 27.25%), CBLN3 and KHNYN (- 23.20% ± 0.80%). Conclusions: Long-read genome-wide methylation profiling can detect obesity-associated epigenetic loci in children. Blood-based markers in genes regulating metabolism and obesity comorbidities could support early risk prediction, patient stratification, and targeted prevention. Extending this work to larger and more diverse cohorts will be necessary to evaluate the robustness of these results and their potential translational relevance.
Keywords: DNA methylation, epigenetics, nanopore sequencing, pediatric obesity
Published in DiRROS: 06.08.2026; Views: 190; Downloads: 122
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Universal dried blood spot screening for congenital cytomegalovirus : a Slovenian national implementation pilot
Nika Eržen, Jernej Kovač, Barbka Repič-Lampret, Urh Grošelj, Aneta Soltirovska Šalamon, Gregor Nosan, 2026, original scientific article

Abstract: Congenital cytomegalovirus infection (cCMV) is the most common congenital infection and an important cause of sensorineural hearing loss and neurodevelopmental impairment, yet many affected infants remain undetected under selective screening approaches. We conducted a prospective national pilot study to evaluate the feasibility and diagnostic yield of universal dried blood spot (DBS)-based screening for cCMV within the Slovenian newborn screening program. DBS samples collected within 72 h of life were tested by polymerase chain reaction (PCR), and screen-positive newborns underwent confirmatory urine PCR within 21 days together with standardized clinical evaluation. Among 5556 screened newborns, 13 (0.23%) screened positive and cCMV was confirmed in 10, corresponding to a lower-bound birth prevalence of 1.80 per 1000 live births (95% confidence interval, 0.98–3.31), because confirmatory testing was limited to DBS-positive newborns. None of the confirmed cases were clinically suspected at birth, and all passed newborn hearing screening. Six infants met protocol-defined criteria for symptomatic cCMV and received valganciclovir. Historical registry-based clinical case ascertainment in Slovenia corresponded to 0.09 detected cases per 1000 live births. These findings demonstrate the feasibility of universal DBS-based cCMV screening within an established newborn screening infrastructure and suggest substantial under-ascertainment under selective clinical detection pathways.
Keywords: cytomegalovirus, CMV, congenital cytomegalovirus infection, newborn screening, NBS, universal screening, dried blood spots, DBS, public health policy
Published in DiRROS: 01.07.2026; Views: 230; Downloads: 189
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7.
Association of BMI, lipid-lowering medication, and age with prevalence of type 2 diabetes in adults with heterozygous familial hypercholesterolaemia : a worldwide cross-sectional study
Amany Elshorbagy, Alexander R.M. Lyons, Antonio J. Vallejo-Vaz, Christophe A. T. Stevens, Kanika I. Dharmayat, Julia M. Brandts, Alberico L. Catapano, Tomas Freiberger, G. Kees Hovingh, Pedro Mata, Urh Grošelj, 2024, original scientific article

Abstract: Background Statins are the cornerstone treatment for patients with heterozygous familial hypercholesterolaemia but research suggests it could increase the risk of type 2 diabetes in the general population. A low prevalence of type 2 diabetes was reported in some familial hypercholesterolaemia cohorts, raising the question of whether these patients are protected against type 2 diabetes. Obesity is a well known risk factor for the development of type 2 diabetes. We aimed to investigate the associations of known key determinants of type 2 diabetes with its prevalence in people with heterozygous familial hypercholesterolaemia. Methods This worldwide cross-sectional study used individual-level data from the EAS FHSC registry and included adults older than 18 years with a clinical or genetic diagnosis of heterozygous familial hypercholesterolaemia who had data available on age, BMI, and diabetes status. Those with known or suspected homozygous familial hypercholesterolaemia and type 1 diabetes were excluded. The main outcome was prevalence of type 2 diabetes overall and by WHO region, and in relation to obesity (BMI ≥30∙0 kg/m²) and lipid-lowering medication as predictors. The study population was divided into 12 risk categories based on age (tertiles), obesity, and receiving statins, and the risk of type 2 diabetes was investigated using logistic regression. Findings Among 46 683 adults with individual-level data in the FHSC registry, 24 784 with heterozygous familial hypercholesterolaemia were included in the analysis from 44 countries. 19 818 (80%) had a genetically confirmed diagnosis of heterozygous familial hypercholesterolaemia. Type 2 diabetes prevalence in the total population was 5·7% (1415 of 24 784), with 4·1% (817 of 19 818) in the genetically diagnosed cohort. Higher prevalence of type 2 diabetes was observed in the Eastern Mediterranean (58 [29·9%] of 194), South-East Asia and Western Pacific (214 [12·0%] of 1785), and the Americas (166 [8·5%] of 1955) than in Europe (excluding the Netherlands; 527 [8·0%] of 6579). Advancing age, a higher BMI category (obesity and overweight), and use of lipid-lowering medication were associated with a higher risk of type 2 diabetes, independent of sex and LDL cholesterol. Among the 12 risk categories, the probability of developing type 2 diabetes was higher in people in the highest risk category (aged 55–98 years, with obesity, and receiving statins; OR 74∙42 [95% CI 47∙04–117∙73]) than in those in the lowest risk category (aged 18–38 years, without obesity, and not receiving statins). Those who did not have obesity, even if they were in the upper age tertile and receiving statins, had lower risk of type 2 diabetes (OR 24∙42 [15∙57–38∙31]). The corresponding results in the genetically diagnosed cohort were OR 65∙04 (40∙67–104∙02) for those with obesity in the highest risk category and OR 20∙07 (12∙73–31∙65) for those without obesity. Interpretation Adults with heterozygous familial hypercholesterolaemia in most WHO regions have a higher type 2 diabetes prevalence than in Europe. Obesity markedly increases the risk of diabetes associated with age and use of statins in these patients. Our results suggest that heterozygous familial hypercholesterolaemia does not protect against type 2 diabetes, hence managing obesity is essential to reduce type 2 diabetes in this patient population
Keywords: Diabetes Mellitus, type 2, aged, risk factors, cross-sectional studies, sladkorna bolezen, tip 2, starostniki, dejavniki tveganja, presečne študije
Published in DiRROS: 12.06.2026; Views: 399; Downloads: 294
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8.
Exploring early DNA methylation alterations in type 1 diabetes : implications of glycemic control
Barbara Čugalj Kern, Jernej Kovač, Robert Šket, Tine Tesovnik, Barbara Jenko Bizjan, Julia Galhardo, Tadej Battelino, Nataša Bratina, Klemen Dovč, 2024, original scientific article

Abstract: Background: Prolonged hyperglycemia causes diabetes-related micro- and macrovascular complications, which combined represent a significant burden for individuals living with diabetes. The growing scope of evidence indicates that hyperglycemia affects the development of vascular complications through DNA methylation. Methods: A genome-wide differential DNA methylation analysis was performed on pooled peripheral blood DNA samples from individuals with type 1 diabetes (T1D) with direct DNA sequencing. Strict selection criteria were used to ensure two age- and sex-matched groups with no clinical signs of chronic complications according to persistent mean glycated hemoglobin (HbA1c) values over 5 years: HbA1c<7% (N=10) and HbA1c>8% (N=10). Results: Between the two groups, 8385 differentially methylated CpG sites, annotated to 1802 genes, were identified. Genes annotated to hypomethylated CpG sites were enriched in 48 signaling pathways. Further analysis of key CpG sites revealed four specific regions, two of which were hypermethylated and two hypomethylated, associated with long non-coding RNA and processed pseudogenes. Conclusions: Prolonged hyperglycemia in individuals with T1D, who have no clinical manifestation of diabetes-related complications, is associated with multiple differentially methylated CpG sites in crucial genes and pathways known to be linked to chronic complications in T1D
Keywords: type 1 diabetes, glycemic control, DNA methylation, diabetes-related complications, long-read sequencing
Published in DiRROS: 08.06.2026; Views: 347; Downloads: 213
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9.
Genetic and clinical characteristics of patients with lipoprotein lipase deficiency from Slovenia and Pakistan : case series and systematic literature review
Quratul Ain, Matija Cevc, Tatiana Marusic, Jaka Šikonja, Fouzia Sadiq, Urša Šuštar, Matej Mlinarič, Jernej Kovač, Hijab Batool, Iqbal Mohammad Khan, Katarina Trebušak Podkrajšek, Barbara Jenko Bizjan, Tadej Battelino, Zlatko Fras, Urh Grošelj, 2024, original scientific article

Abstract: Introduction: Hypertriglyceridemia (HTG) is a complex disorder caused by genetic and environmental factors that frequently results from loss-of-function variants in the gene encoding lipoprotein lipase (LPL). Heterozygous patients have a range of symptoms, while homozygous LPL deficiency presents with severe symptoms including acute pancreatitis, xanthomas, and lipemia retinalis. Methods: We described the clinical characteristics of three Slovenian patients (an 8-year-old female, an 18-year-old man, and a 57-year-old female) and one Pakistani patient (a 59-year-old male) with LPL deficiency. We performed next-generation sequencing (NGS) targeting all coding exons and intron-exon boundaries of the LPL gene, and Sanger sequencing for variant confirmation. In addition, we performed a systematic literature review of all cases with three identified variants and described their clinical characteristics. Results: Two Slovenian patients with a heterozygous pathogenic variant NM_000237.3:c.984G>T (p.Met328Ile) were diagnosed within the first three years of life and had triglyceride (TG) values of 16 and 20 mmol/L. An asymptomatic Pakistani patient with TG values of 36.8 mmol/L until the age of 44 years, was identified as heterozygous for a pathogenic variant NM_000237.3:c.724G>A (p.Asp242Asn). His TG levels dropped to 12.7 mmol/L on dietary modifications and by using fibrates. A Slovenian patient who first suffered from pancreatitis at the age of 18 years with a TG value of 34 mmol/L was found to be homozygous for NM_000237.3:c.337T>C (p.Trp113Arg). Conclusions: Patients with LPL deficiency had high TG levels at diagnosis. Homozygous patients had worse outcomes. Good diet and medication compliance can reduce severity.
Keywords: LPL, case series, hypertriglyceridemia, lipoprotein lipase, lipoprotein lipase deficiency, pancreatitis
Published in DiRROS: 08.06.2026; Views: 309; Downloads: 212
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