Ugotavljanje povezanosti glikemične urejenosti in variabilnosti v genu HIF1A z dolžino telomerov pri bolnikih s sladkorno boleznijo tipa 2

• Main Author: Vedernjak, Blažka
• Other Authors: Trebušak Podkrajšek, Katarina
• Format: Master Thesis
• Language: Slovenian
• Published: 2020
• Subjects: Sladkorna bolezen tipa 2; glikemična urejenost; oksidativni stres; variabilnost v genu HIF1A; dolžina telomerov; Type 2 diabetes; glycaemic control; oxidative stress; HIF1A gene variability; telomere length; sami
• Online Access: https://repozitorij.uni-lj.si/IzpisGradiva.php?id=121532; https://repozitorij.uni-lj.si/Dokument.php?id=136470&dn=

Uvod: Sladkorna bolezen je metabolna bolezen, za katero je značilna hiperglikemija, do katere pride predvsem zaradi motenj v izločanju in/ali delovanju inzulina. Bolniki s sladkorno boleznijo tipa 2 (SBT2) imajo krajše dolžine telomerov v primerjavi z zdravo populacijo. Telomeri so nukleoproteinske strukture na koncih kromosomov, ki ščitijo pred poškodbami in ohranjajo genomsko stabilnost. Namen dela: V magistrski nalogi želimo preveriti vpliv glikemične urejenosti in HbA1c na krajšanje telomerov pri SBT2. Glikemično urejenost bomo izrazili kot koncentracijo glukoze na tešče, koeficient variacije meritev glukoze na tešče, odstotek meritev glukoze v ciljnem območju in vrednost glikiranega hemoglobina (HbA1c). Preverili bomo tudi vpliv variabilnosti gena HIF1A, ki je transkripcijski faktor odziva na hipoksijo. Metode: V raziskavo smo vključili 155 bolnikov s SBT2 obeh spolov z več let trajajočo SBT2. Ob odvzemu vzorca za izolacijo DNA je bil hkrati izmerjen HbA1c, meritev glukoze na tešče pa so preiskovanci izvajali sami in vrednosti zapisovali v knjižice za samokontrolo. Dolžino telomerov smo določili s kvantitativnim PCR pristopom z modificirano Cawthonovo metodo, genotipizacijo izbranega polimorfizma gena HIF1A pa z alelno specifično PCR metodo (KASP). Statistična analiza je potekala v programu SPSS. Rezultati: V preiskovanem vzorcu starost, spol in trajanje SBT2 niso bili povezani z dolžino telomerov. Tudi sama urejenost glikemije (variabilnost glukoze na tešče in HbA1c) ni vplivala na dolžino telomerov. Dolžina telomerov tudi ni bila povezana z genotipom HIF1A. Med posameznimi skupinami (dosega/ne dosega ciljne vrednosti HbA1c, nizek/visok HbA1c, glikemična variabilnost, genotip HIF1A) nismo opazili statistično pomembnih razlik v povprečni dolžini telomerov. Razprava z zaključki: Številne raziskave nakazujejo, da imajo posamezniki s SBT2 krajše telomere v primerjavi z zdravo populacijo. V raziskavi smo preverili številne kazalce urejenosti SBT2, vendar njihovega vpliva na dolžino telomerov nismo uspeli dokazati. Vzrok za to je verjetno premajhno število bolnikov, ki so bili vključeni v raziskavo. Na dobljene rezultate pa morda vpliva tudi dejstvo, da rezultati kontinuiranih meritev glukoze niso bili na voljo. Prospektivna raziskava s spremljanjem bolnikov v daljšem časovnem obdobju bi morda lahko potrdila zastavljene hipoteze. Background: Diabetes is a metabolic disease characterized by hyperglycaemia, which occurs mainly due to deficiencies in the secretion and/or function of insulin. Patients with type 2 diabetes (T2D) have shorter telomere lengths compared to healthy population. Telomeres are nucleoprotein structures at the ends of chromosomes that are protective against degradation and have a role to maintain genomic stability. Aim: In the following thesis we want to examine the influence of glycaemic regulation and HbA1c on telomere shortening in T2D. Glycaemic control will be expressed as the concentration of fasting blood glucose, coefficient of variation of fasting glucose measurements, the percentage of glucose measurements in the target range and the value of glycated haemoglobin (HbA1c). In addition, we will examine the impact of the HIF1A gene encoding a transcription factor of response to hypoxia. Methods: We have included 155 patients with T2D in the study cohorts, representing patients of both sexes and with a disease lasting fot several years. HbA1c was measured at the same time as DNA sample was taken. Fasting blood glucose was measured by the subjects themselves and recorded in booklets for self-monitoring. Telomere length was determined by quantitative PCR approach with modified Cawthons method. Genotyping of the selected HIF1A gene polymorphism was performed by the allele-specific PCR method known as KASP. The statistical analysis was carried out in the SPSS program. Results: In the examined sample, age, sex and disease duration were not associated with telomere length. Glycaemic control (fasting blood glucose variability and HbA1c) did not affect telomere length. Telomere length was also not related to the HIF1A genotype. No statistically significant differences in mean telomere length were observed between individual groups (reaching/not reaching target value of HbA1c, low/high HbA1c, glycaemic variability, HIF1A genotype). Conclusions: Many studies indicate that patients with T2D have shorter telomeres compared to the healthy population. We have tested several diabetes related factors, but we have not been able to prove their effect on the telomere attrition. This is most likely due to the small study cohort. The results may also be affected by the fact that the results of the continuous blood glucose measurements were not available. On the other hand, prospective follow-up study of patients over a longer period of time might confirm the hypothesis of this study.