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EPIDEMIOLOGY AND GENETICS OF ALZHEIMER´S DISEASE. Jana Povova, Omar Sery, Hana Tomaskova, Petr Ambroz, Anna Pohlidalova, Vladimir Janout Department of Epidemiology and Public Health, Ostrava, Czech Republic Department of Biochemistry, Brno, Czech Republic. INTRODUCTION.
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EPIDEMIOLOGY AND GENETICS OF ALZHEIMER´S DISEASE Jana Povova, Omar Sery, Hana Tomaskova, Petr Ambroz, Anna Pohlidalova, Vladimir Janout Department of Epidemiology and Public Health, Ostrava, Czech Republic Department of Biochemistry, Brno, Czech Republic
INTRODUCTION • Itisgenerallyacceptedthat Alzheimer´s disease (AD) isthe most frequentformofdementia. • Etiology of AD isstillunknown and there are threehypotheses, what risk factors are responsiblefordevelopmentofthedisease: - vascular risk factors - genetic risk factors - behavioral risk factors
EPIDEMIOLOGY • Fromdifferentreasonsthere are no exact data aboutthe incidence and prevalence of AD - no compulsorynotification - difficult to distinguishbetweendifferent formsofdementia - no exactdiagnostic test • There are mostlyonlyestimatesofreal incidence or prevalence … in theCzechRepublic 120 000 casesof AD notified
STUDY • Since 2010 wehavebeenperforminganepidemiological study to assesstheimportanceofselected risk factorsfromvascular and geneticfields. • Theaimofthe study is to recruit 800 casesof AD and 800 controls. • In thispaperwe report somepreliminaryresultsfromanalysesof 394 cases and 287 controls.
DIAGNOSTIC CRITERIA • CASES - MMSE < 24 - slowdevelopmentofcognitiveimpairment - otherformsofdementiaexcluded (CT exam.) • CONTROLS - MMSE > 28 - samegenderandage (± 5 years)
EPIDEMIOLOGICAL DATA • Recruitment: 394 Cases 130 Controls • Gender: 79 % females 76 % females • Age (average) 79 73 • 96,7 % of cases with late onset (after 65 years) • Education: in group of cases 49 % elementary,72 % lower than high school in group of controls 36 % high school • Clinical course: in 85 % slow
GENETICS • We start withfocusing on genes: - Apolipoprotein E (ApoE) - Angiotensin Converting Enzyme (ACE) • Gene forApoEisfound on chromosome 19q13.2 and has 3 major alleles 2,3,4. • It has 6 genotypesdepending on combinationof these threealleles. • Theallele 4 istheonlyconfirmedgeneticfactorcontributing to both early and lateonsetof AD.
GENETICS • ACE gene islocated on the chromosome 17q23 and has 2 major alleles I and D. • It has 3 genotypes depending on combination of these two alleles. • Itwasreportedthatthe ID and II genotypes are associatedwiththe risk of AD (DD genotype isconsidered as neuroprotective).
Apolipoprotein E (ApoE) • ApoE4 allelesignificantlyincreasethe risk of AD. (OR 2,52; 95% CI 1,832-3,482) • In bothfilesthe genotype E3/E3 was most frequent (cases 47 % andcontrols 60 %) • Thefrequencyof genotype E4/E4 was in cases 3 %, in controls 0,3 % only.
Genotypes ACE • Allele I increases risk of AD (OR 1,08; 95% CI 0,87 – 1,34) but so far difference is not significant. • In both files the genotype ID was most frequent – cases 49 % and controls 57 %. • Genotype II was in cases in 22 % and in controls in 17 % (marginal significant difference – OR 1,43 95% CI 0,97-2,12)
Conclusions – vascular risk factors • In patientswith AD were CVD more often in theirhistorycompare to controlsbutthedifferencewas not significant. • Diabetes, strokeandhypertensionwereinverselyrelated to AD whatiscontrary to somepublishedresults. • In case ofhypertensiontheinversaldifferencewasstatisticalysignificant. Thesamefindingwaspublished by someotherresearchers.
Conclusions – genetic risk factors • Relationship between ApoE4 allele and AD was confirmed in presented paper with high statistical significance, what make it possible diagnostic marker for AD. • In ACE gene was only marginal reliance of alelle I presence and higher risk of AD development.