Γενετική της αρτηριακής δομής και λειτουργίας Χ. Αντωνιάδης Καρδιολόγος Department of Cardiovascular Medicine, John Radcliffe Hospital, University of Oxford 1 η Καρδιολογική Κλινική, Ιατρική Σχολή Πανεπιστημίου Αθηνών
Research tool 2 (GWAS) Genetics in cardiovascular medicine Genetic background Research tool 1 (candidate gene approach) Intermediate Phenotypes Endothelial function of small/large vessels Elastic properties of arterial wall Vascular redox signalling/biology Environment Cardiovascular disease
Genetics in cardiovascular disease Research tool 1: The candidate gene approach Therapeutic targets Predictive models Known pathophysiology Cardiovascular risk Vascular structure/function Identify candidate key molecules Genetic variability of these molecules (SNPs Haplotypes)
Pathophysiology of atherosclerosis/plaque rupture Antoniades C et al; J Am Coll Cardiol 2009;54:669 77
Candidate gene association studies MTHFR CRP Fib Yamada et al; Genomic Med. 2008 2:7 22
Genetics of endothelial dysfunction enos Variability of enos gene Variability of enos co-factors
IMA BH4 (pmol/g) Genetic variability and enos activity enos O 2 GTPCH oxygenase Fe BH4 Fe reductase reductase BH4 oxygenase L-arginine L-citrulline 60 P<0.01 NO. Ο 2-40 20 ΧΧ (2% of Greek population) 0 Antoniades C et al, Circulation 2006;114:1193-1201 OO XO XX Antoniades C et al. J Am Coll Cardiol 2008;52:158-65
How can we take advantage of genetic knowledge to investigate cardiovascular disease pathogenesis?
Why is GCH1 X haplotype of particular interest for vascular function? Antoniades C et al; Circulation 2011;124:1860-1870 Are the GCH1 XX homozygotes candidates for oral BH4 treatment? Antoniades C et al; Circulation. 2007;116:2851-2859 OXBIO study Cunnington et al; Circulation 2012 (in press)
Entering a new era in cardiovascular genetics From SNPs, to haplotypes and now to GWAS! 1. Simultaneous genotyping for 500,000 1,000,000 SNPs across the genome 2. Thinking about chromosomes/loci instead of genes 3. Typically needs thousands of participants, due to multiple comparisons errors/type I error. Thresholds for p-values: 5 10 8 (corresponding to 0.05 after adjustment for 1 million independent Tests!)
GWAS: A new approach How to read the results of GWAS studies? Is it an expert s job? P value:~10-13 Example: GWAS for CAD 9p21 locus CDKN2A/CDKN2B HR: 1.3 LDLR (9p13) HR: 1.15 Lotta et al; Lancet 2011; 377: 356-8 Samani et al; N Engl J Med 2007;357:443-53
CDKN2A mrna (Relative units) CDKN2B mrna (Relative units) The 9p21 locus in acute myocardial infarction Samani NJ et al; N Engl J Med 2007;357:443-53. 10 P=0.05 0 4 P=0.036 2 McFerson et al; N Engl J Med 2010; 362;18 0 AA/AG GG Antoniades et al; 2012 (in revision) CDKN2A/2B as novel therapeutic targets for cardiovascular disease
Lacolley at al; Cardiovascular Research (2009) 81, 637 648 GWAS targeting stiffness IGF1R LPL MTHFR enos IGF-BP1-3
Re-writing the genetics of FMD: The GWAS tool GWAS study: 1345 participants Afymmetrix GeneChip 100,000 SNPs Vasan et al; BMC Medical Genetics 2007, 8(Suppl 1):S2 Genetic variability of FMD Limited or no effect on cardiovascular risk!!!
GWAS targeting ABI, cimt, coronary calcification Genetic variability of cimt, ABI, CC Limited or no effect on cardiovascular risk!!! O Donnell et al; BMC Medical Genetics 2007, 8(Suppl 1):S4
Is it time to re-write cardiovascular genetics? Genetic loci FMD, cimt, ABI, CC Aortic distensibility Cardiovascular risk Probably it is time to re-write cardiovascular pathophysiology!!!!
Conclusions Candidate gene approach: Variability of ~300 genes had been associated with changes in vascular structure/function GWAS studies: CDKN2A/CDKN2B (ANRYL) 9p21 locus affect both arterial stiffness and cardiovascular risk The loci affecting FMD, cimt, ABI, CC: DO NOT affect cardiovascular risk!! Time to re-define the role of these intermediate phenotypes in CVD?
Acknowledgments University of Oxford, UK Marios Margaritis Alexios Antonopoulos Regent Lee Tim Van Assche Colin Cunnington Barbara Casadei Keith M. Channon Dpt of Cardiology, University of Athens Costas Bakogiannis Michael Demosthenous Costas Psarros Dimitris Tousoulis Christodoulos Stefanadis Dpt of Physiology, University of Athens Kyriakoula Marinou Michael Koutsilieris Dpt Cardiac Surgery, JR hospital Oxford, UK David Taggart Rana Sayeed Ravi DeSilva Mario Petrou Dpt Cardiac Surgery, Hippokration Hospital Themis Psarros Costas Triantafyllou George Ekonomopoulos Dimitris Lymperiadis Nikos Sfyras Nikos Koumallos University of Cracow, Poland Tomasz J. Guzik University of Frankfurt Germany Irmgart Tegeder Harvard Medical School, USA Mike Costigan CJ Woolf Funding bodies: British Heart Foundation European Commission (IEF, RIG) BRC/NIHR European Society of Cardiology EAPCI European Heart Failure Association Hellenic Cardiological Society
GWAS for MI and CAD Journal: Science Journal: Nature Genetics Lotta et al; Lancet 2011; 377: 356-8
Genetic variability of enos protein and ACS G894T: TT increased proteolytic cleavage of enos Cass et al; Circulation. 2004;109:1359-1365 GT+TT GG No effects on enos coupling Limited pathophysiological importance Antoniades C et al; J Am Coll Cardiol 2005;46:1101 9
Φαρμακογενετική αγωγής με στατίνες Mangravite et al; Curr Opin Lipidol 2009;18:409 414
Genetics: Basic principles the classical approach reaching its limits promoter Gene TYPICAL GENE= nx10 3 b (A, G, C, T) Polymorphisms Silent Over-expression Hypo-expression Non-functional product Unstable product...agggtatggtgaagtcctcct.....agggtatgatgaagtcctcct...agggtatggttgagtgaagtcctcct...agggtgaagtcctcct Haplotypes Antoniades C et al, J Am Coll Cardiol 2008;52:941 52
Candidate gene approach
Candidate gene approach and validation of intermediate phenotypes Genetic background Research tool 1 (candidate gene approach) Intermediate Phenotypes FMD, cimt, PWV, Aix, ABI Environment Cardiovascular disease Validation through genetic variability