Title Globalna DNA metilacija i trisomija 21 : doktorski rad
Title (english) Global DNA Methylation; Chromosomal Nondisjunction; Trisomy 21
Author Ivana Babić Božović
Mentor Bojana Brajenović-Milić (mentor)
Mentor Aleksandra Stanković (komentor) VIAF: 115146331978318692467
Committee member Blaženka Grahovac (predsjednik povjerenstva)
Committee member Maja Vlahović (član povjerenstva)
Committee member Oleg Petrović (član povjerenstva)
Committee member Bojana Brajenović-Milić (član povjerenstva)
Committee member Aleksandra Stanković (član povjerenstva) VIAF: 115146331978318692467
Granter University of Rijeka Faculty of Medicine Rijeka
Defense date and country 2013-04-03, Croatia
Scientific / art field, discipline and subdiscipline BIOMEDICINE AND HEALTHCARE Clinical Medical Sciences
Universal decimal classification (UDC ) 616 - Pathology. Clinical medicine
Abstract Osnovni cilj ovog rada bio je utvrditi povezanosti globalne DNA metilacije i nepravilnog razdvajanja kromosoma 21 tijekom oogeneze i razvoja prirođenih srčanih grešaka (engl. congenital heart defects, CHD) u sklopu Down sindroma (DS). Dodatno, ispitivan je i utjecaj endogenih i egzogenih čimbenika na globalnu DNA metilaciju, kao što su MTHFR C677T polimorfizam, spol, starosna dob, indeks tjelesne mase, unos folata putem prehrane, perikoncepcijski unos pripravaka folata, uživanje duhanskog dima i alkohola te primjena lijekova.
Ispitanici i metode: U istraživanje je bilo uključeno 94 majki djece s DS-om majčinog podrijetla u kojih je točno određena mejotička dioba u kojoj je došlo do nerazdvajanja kromosoma 21. Kontrolnu grupu su činile majke zdrave djece i uredne obiteljske i osobne anamneze (N=100). Utjecaj globalne DNA metilacije na razvoj sindromskog CHD-a ispitivan je na uzorku od 42 osobe s DS-om koje su ujedno djeca majki uključenih u ovo istraživanje. Globalna DNA metilacija analizirana je u limfocitima periferne krvi, kvantifikacijom metilacije LINE-1 pomoću MethyLight metode. Genotipizacija MTHFR C677T polimorfizma izvedena je PCR-RFLP metodom.
Rezultati: Globalna DNA metilacija u majki djece s DS-om je statistički značajno niža nego u majki zdrave djece (P=0,000), ali se ne razlikuje ovisno o mejotičkoj diobi u kojoj je došlo do nerazdvajanja kromosoma 21 (P=1,000), kao ni u odnosu na prisustvo CHD-a u njihove djece (P=0,951). Vrijednost globalne DNA metilacije je statistički značajno povezana s kombinacijom MTHFR C677T genotip/prehrana (R2=4,5%; P=0,046). Najniže vrijednosti globalne DNA metilacije su imale majke CT+TT genotipa i prehrane siromašne folatima. Doprinos ovog čimbenika na varijabilnost globalne DNA metilacije još je veći u majki kod kojih se dogodilo nerazdvajanje kromosoma tijekom prve mejotičke diobe (R2=6,2%; P=0,036), a najveći udio utvrđen je u majki djece s DS-CHD+ (R2=9,9%; P=0,026), i to posebno u majki djece s DS-om i septalnim defektom (R2=15,4%; P=0,018). Globalna DNA metilacija u ispitanika s DS-om se statistički značajno ne razlikuje ovisno o prisutnosti CHD-a (P=1,000), ali ju statistički značajno opisuje spol osobe (R2=19,1%; P=0,025).
Zaključak: U našem istraživanju utvrđena je globalna DNA hipometilacija u majki djece s DS-om regularnog tipa majčinog podrijetla što ju opisuje kao mogućeg čimbenika rizika za nepravilno razdvajanje kromosoma 21 tijekom oogeneze. Iako nije utvrđena povezanost globalne DNA metilacije i CHD-a u sklopu DS-a, njen se utjecaj ne može potpuno isključiti jer na njene vrijednosti utječu MTHFR genotip i prehrana majke, čiji bi se učinak mogao ispoljiti na većem broju ispitanika.
Abstract (english) The aim of this study was to determine the association between global DNA methylation and nondisjunction of chromosome 21 during oogenesis and occurence of congenital heart defects (CHD) in Down syndrome (DS). Additionally, the imact of endogenous and exogenous factors on global DNA methylation was analyzed, including MTHFR C677T polymorphism, gender, age, body mass index, intake of folate through diet, periconceptional folic acid supplementation, smoking, alcohol drinking and medication use.
Patients and methods: A total of 94 mothers of children with DS of maternal origin and with defined meiotic stage of chromosome nondisjunction have been enrolled in this study. The control group consisted of mothers of healthy children with no personal or family history (N=100). The influence of global DNA methylation on development of CHD was studied in 42 DS probands who were the children of mothers included in this study. Global DNA methylation was analyzed in peripheral blood lymphocytes by quantification of LINE-1 methylation using MethyLight method. Genotyping of MTHFR C677T polymorphism was performed by PCR-RFLP.
Results: Global DNA methylation in mothers of children with DS was significantly lower than in mothers of healthy children (P=0.000), but no significant differences were found regarding the meiotic stage of nondisjunction of chromosome 21 (P=1.000) or regarding the presence of CHD in their children (P=0.951). Combination of MTHFR C677T genotype/diet significantly influenced global DNA methylation (R2=4.5%, P=0.046). The lowest values of global DNA methylation were determined in mothers with CT+TT genotype and low folate diet. The contribution of these factors was even higher among mothers of children with trisomy 21 resulted from meiotic one nondisjunction (R2=6.2%, P=0.036). The highest effect was found in mothers of children with DS-CHD+ (R2=9.9%, P=0.026), particularly among those who had children with DS and septal heart defect (R2=15.4%, P=0.018). In DS probands, no significant differences in global DNA methylation were found according to the presence of CHD (P=1.000), but values of global DNA methylation were significantly influenced by gender (R2=19.1%; P=0.025).
Conclusion: Our findings revealed global DNA hypomethylation in mothers of children with DS, suggesting that this is a possible risk factor for nondisjunction of chromosomes 21 during oogenesis 21. Although, global DNA methylation was not significantly associated with development of CHD in DS, its influence can not be completely excluded, since the significant impact of MTHFR genotype and diet on global DNA methylation in mothers of DS-CHD+ was determined. Further analyses on larger sample are needed to provide an answer to this question.
Keywords
DNA metilacija
globalna
Kromosomsko nerazdvajanje
Prirođene srčane greške
Down sindrom
Keywords (english)
DNA methylation
global
Nondisjunction
genetic
Congenital heart defects
Down syndrome
Language croatian
URN:NBN urn:nbn:hr:188:863850
Study programme Title: Biomedicine Postgraduate (doctoral) study programme Study programme type: university Study level: postgraduate Academic / professional title: doktor/doktorica znanosti, područje biomedicine i zdravstvo (doktor/doktorica znanosti, područje biomedicine i zdravstvo)
Catalog URL https://libraries.uniri.hr/cgi-bin/unilib.cgi?form=D1130402068
Type of resource Text
Extent 108 str.
File origin Born digital
Access conditions Closed access
Terms of use
Created on 2017-01-19 19:06:19