Projects / Programmes
Biogenetic and epigenetic markers of obesity and metabolic syndrome in children and adolescents
| Code |
Science |
Field |
Subfield |
| 3.05.00 |
Medical sciences |
Human reproduction |
|
| Code |
Science |
Field |
| B660 |
Biomedical sciences |
Pediatrics |
| Code |
Science |
Field |
| 3.02 |
Medical and Health Sciences |
Clinical medicine |
obesity, prediabetes, genetics, pharmacogenetics, child, adolescent
Researchers (24)
Organisations (3)
Abstract
Obesity in children and adolescents is one of the most important public healthcare problems in the world and in Slovenia.
Genetic background has an important influence on body mass index (BMI). Polygenic obesity in children is associated with genetic variants in several genes and some are specific for children (FTO, MC4R in TMEM18). To-date identified genetic variants explain a relatively minor proportion in the variability of BMI. Undetermined genetic variants and also epigenetic variants e.g. methylation pattern variants and miRNA molecules, probably have an important role. Candidate regions where methylation variants could influence the development of obesity are promotor regions in genes associated with energy intake and consumption (e.g. POMC, MC4R) and genes associated with adipogenesis as DEPTOR, a new gene associated with obesity that was first described by a part of the proposed project group and is to date unexplored in children. Determining epigenetic mechanisms involved in obesity is also important in the evaluation of interventions.
Fat accumulation in the liver and muscle and adipose tissue dysfunction lead to systemic insulin resistance and hyperinsulinism, that is not only associated with the development of type 2 diabetes (T2D) but independently with the development of atherosclerosis and cardiovascular diseases. Therefore we allocated an important part of the proposed project to determining differences between children and adolescent with and without hyperinsulinism. Variants in the genes related to actions and excretion of insulin are candidate genes for prediabetes – hyperinsulinism (INSR, TCF7L2, IGF2BP2, CDKAL1, HHEX, HNF1A). Association between methylation patterns and obesity and obesity complications are described (PGC1alfa). Role of miRNA in the development of prediabetes in children and adolescents is poorly researched.
Metformin is the main medication for T2D in adolescents. It increases tissues sensitivity for insulin and thereby lowers circulating insulin levels, which is an important effect in the treatment of obesity complications. Organic cation transporters (OCT1, OCT 2, MATE) have an important role in metformin transport. Genetic variants in these genes are associated with decreased efficacy of metformin in T2D adults. Inter-individual variability in genetic variants in these genes could influence metformin treatment outcome in adolescents with prediabetes.
In regard to the extent of the discussed problem and its long-term consequences it is imperative to immediately develop preventive and therapeutic strategies to lower prevalence of obesity and early find subjects at an increased risk of early complications. From this aspect it is imperative to determine population specific pathogenesis of obesity and its complications. Aims of the study are (1) to determine genetic and epigenetic predisposition for obesity and (2) prediabetes – hyperinsulinism in Slovenian children and adolescents and (3) to determine genetic markers of the efficacy of metformin treatment in obese adolescents with prediabetes.
All methods to be used are already implemented or are in the process of implementation in the participating institutions (1) high resolution melting analysis (HRM) and Sanger sequencing (2) genome-wide association study (GWAS) of pooled samples (3) bisulfite sequencing for determination of DNA methylation patterns (4) next generation sequencing (NGS) and real-time PCR of selected miRNA and (5) allele-specific real-time PCR.
Results would be used to produce clinical algorithms that would be directly implemented in clinical use, significantly improving healthcare of children and adolescents at an increased risk.
Significance for science
Results of the research project significantly contributed to the basic knowledge in the fild of childhood obesity and its complications, especially insulin resistance that is considered one of the most important. By project conclusion we managed to publish 3 research articles in important scientific journals that cover fields of childhood obesity and paediatric diabetes (International Journal of Obesity, Pediatric Obesity in Pediatric Diabetes). Further article is in the process of revision. Based on the results of the project 2 diplomas in the master degree programme BIOCHEMISTRY were successfully defended. By determining the prevalence of mutations in the MC4R gene that is most frequently affected in monogenic forms of obesity and FTO gene that is most frequently affected in poligenec obesity we corroborated the role of genetic testing in morbidly obese children. Using the next generation sequencing method in individuals with morbid obesity we confirmed the role of this type of diagnostics in determination of novel genes associated with certain traits. We were among the first to determine INPP5E as a novel candidate gene for further studies on appetite disregulation and obesity. Most significant scientific contribution was in the field of insulin resistance aetiology. SNPs in the promotor region of DEPTOR gene were for the first time associated with an increased risk of insulin resistance in obese children. By this DEPTOR become a novel candidate gene not only for obesity but also its complication insulin resistance. This will have important consequences not only for the diagnostic purposes, but possibly also for development of type 2 diabetes treatment. Furthermore we were the first to use genome wide association study on pooled DNA samples for the determination of novel genes associated with insulin resistance. By further analysis we determined PYGB gene as a novel candidate gene. By further data analysis we expect to determine further novel candidate genes. Significant part of the project was also devoted to the development of metodologies for methylation patters which is one of the main epigenetic mechanisms influencing gene expression. We studied methylation patterns in known genes associated with obeisty and insulin resistanece and in the promotor region of gene DEPTOR. Significant contribution was done by investigating the role of non-coding RNA in obeisty complications namelly non-alcoholic liver steatosis. In cooperation with two internationa research teams role of miR-122 was linked to pathogenesis of this complication in obese prepubertal children.
Significance for the country
Childhood obesity and its complications are a mayor public health problem in Slovenia. Due to the high prevalence of childhood obesity and its long-term health complications it is imperative to develop mechanisms for early identification and treatment of those at an increased risk for obesity and its complications. To this effect it’s of paramount importance to determine population specific pathogenesis of obesity and its complications. Prevalence of mutations in the gene that is most frequently associated with monogenic form of obesity and prevalence of SNP in the gene most frequently associated with polygenic form of obesity was determined. Metodology that was developed will be further used in the diagnostic procedures of the Department of Endocrinology, Diabetes and Metabolism at the University Children’s hospital in Ljubljana that it the terciary c3nter for management of childhood obesity and its complications. Of importance for Slovenia is also the that the biochemical methods for the determination of genetic and epigenetic mechanism of insulin resistance, that is one of the fundamental pathophysiological mechanisms of obesity complications, were developed. Based on the results of the project we are able to better predict predisposition for obesity complication in obese children. This enables us to provide more intense conservative and medicamentous treatment to those at an increased risk with the goal of preventing early complications of obesity which should decrease long-term morbidity of this population. In addition, scientific publications and lectures at international meeting contributes to better recognition of Slovenia and creates opportunities for further scientific collaboration and possible foreign investments in the development of services and products with high added value.
Most important scientific results
Annual report
2014,
2015,
final report
Most important socioeconomically and culturally relevant results
Annual report
2014,
2015,
final report
