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Silvia Borras Aberdeen

DEVELOPING A DIAGNOSTIC SERVICE FOR ARRHYTHMOGENIC RIGHT VENTRICULAR DYSPLASIA / CARDIOMYOPATHY (ARVD/C) IN SCOTLAND. Silvia Borras Aberdeen. TALK OUTLINE. Natural history of ARVD/C Molecular genetics, pathogenicity model and PKP2 gene involvement Proposed strategy of PKP2 screening

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Silvia Borras Aberdeen

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  1. DEVELOPING A DIAGNOSTIC SERVICE FOR ARRHYTHMOGENIC RIGHT VENTRICULAR DYSPLASIA / CARDIOMYOPATHY (ARVD/C) IN SCOTLAND Silvia Borras Aberdeen

  2. TALK OUTLINE • Natural history of ARVD/C • Molecular genetics, pathogenicity model and PKP2 gene involvement • Proposed strategy of PKP2 screening • Validation study results • Conclusions • Future work • Acknowledgements

  3. NATURAL HISTORY OF ARVD/C • one of the major causes of sudden cardiac death in young and athletes (Thiene et al, 1988; Peters, 2006) • progressive myocardial atrophy of the RV with fibro-fatty replacement • ventricular electric instability with syncopes and palpitations due to ventricular tachycardias or fibrillations originating in the RV • a degree of the LV involvement is reported in up to 75% patients Prevalence: • 1:5000 (McKenna, 1994) with familial occurrence of 50% Regional variations: increased incidence in the population of Greek island Naxos 0.4 – 0.8% (Thiene and Basso, 2001) Veneto region of Italy – ARVD/C accounts for 20% of all sudden deaths (Thiene et al, 2001) RV

  4. (taken from Thiene et al, 2007) NATURAL HISTORY OF ARVD/C • one of the major causes of sudden cardiac death in young and athletes (Thiene et al, 1988; Peters, 2006) • progressive myocardial atrophy of the RV with fibro-fatty replacement • ventricular electric instability with syncopes and palpitations due to ventricular tachycardias or fibrillations originating in the RV • a degree of the LV involvement is reported in up to 75% patients Prevalence: • 1:5000 (McKenna, 1994) with familial occurrence of 50% Regional variations: increased incidence in the population of Greek island Naxos 0.4 – 0.8% (Thiene and Basso, 2001) Veneto region of Italy – ARVD/C accounts for 20% of all sudden deaths (Thiene et al, 2001) RV

  5. (taken from http://ourworld.compuserve.com/home pages/arvc) NATURAL HISTORY OF ARVD/C • one of the major causes of sudden cardiac death in young and athletes (Thiene et al, 1988; Peters, 2006) • progressive myocardial atrophy of the RV with fibro-fatty replacement • ventricular electric instability with syncopes and palpitations due to ventricular tachycardias or fibrillations originating in the RV • a degree of the LV involvement is reported in up to 75% patients Prevalence: • 1:5000 (McKenna, 1994) with familial occurrence of 50% Regional variations: increased incidence in the population of Greek island Naxos 0.4 – 0.8% (Thiene and Basso, 2001) Veneto region of Italy – ARVD/C accounts for 20% of all sudden deaths (Thiene et al, 2001) RV

  6. (taken from McRae et al, 2001) NATURAL HISTORY OF ARVD/C • one of the major causes of sudden cardiac death in young and athletes (Thiene et al, 1988; Peters, 2006) • progressive myocardial atrophy of the RV with fibro-fatty replacement • ventricular electric instability with syncopes and palpitations due to ventricular tachycardias or fibrillations originating in the RV • a degree of the LV involvement is reported in up to 75% patients Prevalence: • 1:5000 (McKenna, 1994) with familial occurrence of 50% Regional variations: increased incidence in the population of Greek island Naxos 0.4 – 0.8% (Thiene and Basso, 2001) Veneto region of Italy – ARVD/C accounts for 20% of all sudden deaths (Thiene et al, 2001) RV

  7. (taken from http://en.wikipedia.org/wiki/Left_bundle_branch_block) NATURAL HISTORY OF ARVD/C • one of the major causes of sudden cardiac death in young and athletes (Thiene et al, 1988; Peters, 2006) • progressive myocardial atrophy of the RV with fibro-fatty replacement • ventricular electric instability with syncopes and palpitations due to ventricular tachycardias or fibrillations originating in the RV • a degree of the LV involvement is reported in up to 75% patients Prevalence: • 1:5000 (McKenna, 1994) with familial occurrence of 50% Regional variations: increased incidence in the population of Greek island Naxos 0.4 – 0.8% (Thiene and Basso, 2001) Veneto region of Italy – ARVD/C accounts for 20% of all sudden deaths (Thiene et al, 2001) RV

  8. NATURAL HISTORY OF ARVD/C • one of the major causes of sudden cardiac death in young and athletes (Thiene et al, 1988; Peters, 2006) • progressive myocardial atrophy of the RV with fibro-fatty replacement • ventricular electric instability with syncopes and palpitations due to ventricular tachycardias or fibrillations originating in the RV • a degree of the LV involvement is reported in up to 75% patients Prevalence: • 1:5000 (McKenna, 1994) with familial occurrence of 50% Regional variations: increased incidence in the population of Greek island Naxos 0.4 – 0.8% (Thiene and Basso, 2001) Veneto region of Italy – ARVD/C accounts for 20% of all sudden deaths (Thiene et al, 2001) RV

  9. NATURAL HISTORY OF ARVD/C • one of the major causes of sudden cardiac death in young and athletes (Thiene et al, 1988; Peters, 2006) • progressive myocardial atrophy of the RV with fibro-fatty replacement • ventricular electric instability with syncopes and palpitations due to ventricular tachycardias or fibrillations originating in the RV • a degree of the LV involvement is reported in up to 75% patients Prevalence: • 1:5 000 (McKenna, 1994) Regional variations: increased incidence in the population of Greek island Naxos 0.4 – 0.8% (Thiene and Basso, 2001) Veneto region of Italy – ARVD/C accounts for 20% of all sudden deaths (Thiene et al, 2001) RV

  10. GENETICS OF ARVD/C

  11. DESMOSOMAL MODEL OF PATHOGENICITY Defects in desmosomes >> affected signal transduction between myocytes >> myocyte detachment and apoptosis >> inflammatory process >> fibro-fatty substitution >> intraventricular conduction delay of the electrical impulse >> life-threatening arrhythmias. (adapted from www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1483166#B7, MacRae et al, 2006)

  12. PKP2 GENE INVOLVEMENT PKP2 mutation prevalence: • UK: 27%(32/120), Gerull et al (2004) • Holland:43-52%(24/56; 43/82), van Tintelen et al (2006), van der Smagt (2007), respectively • The US: 43% (25/58), Dalal et al (2006) >> patients with PKP2 mutation present with arrhythmia earlier than the patients with a mutation in other ARVD/C genes

  13. Most frequent mutations in PKP2 gene (taken from Awad, 2008) PKP2 GENE INVOLVEMENT PKP2 mutation prevalence: • UK: 27%(32/120), Gerull et al (2004) • Holland:43-52%(24/56; 43/82), van Tintelen et al (2006), van der Smagt (2007), respectively • The US: 43% (25/58), Dalal et al (2006) >> patients with PKP2 mutation present with arrhythmia earlier than the patients with a mutation in other ARVD/C genes

  14. PKP2 Screening strategy Extraction of genomic DNA from blood or tissue samples Primer design PCR amplification of all 14 exons (16 fragments) Gel electrophoresis of selected samples Sequencing of successfully amplified PCR products Sequence analysis Confirmation of samples with identified sequence change MLPA analysis (SALSA MLPA kit P168 PKP2, MRC Holland) MATERIALS & METHODS Cohort: Males – 16 Females - 5 • Aim: • Introduce a molecular screening service for PKP2 gene • Validate the method on previously tested DNA samples • Set up a molecular genetic testing of PKP2 gene Reason for referral

  15. c.148_151delACAG; p.thr50ser fsX61 in exon 1 of PKP2 gene RESULTS Patient 1: 20061443 • 54-year old female referred due to FH Symptoms: • light palpitations, runs of VT lasting 5-10 minutes abnormal ECHO >1000 premature beats in 24-hour Holter monitoring

  16. c.663C>A; p.tyr221stop in exon 3 Patient 2: 20062522 • 43-year old male Symptoms: • exercise-induced VT age 22 extensive dilation of RV and hypokinesia age 41

  17. Patients 3 & 4: 20071165 & 20071255 55 and 50-year old males Symptoms: two episodes of VT in their 30s c.2197_2202insGdelCACACC; A733fsX740 in exon 11

  18. c.1759G>A; p.val587ile in exon 8 c.209G>T; p.ser70ile in exon 1 Patient 5: 20072636 • 26-year old male Symptoms: • exercise-induced VT

  19. VALIDATION STUDY SUMMARY c.1097T>C; p.leu366pro SNP was detected in exon 4 in five patients and a number of intronic SNPs in fragments 6,10,12,13 and 14.

  20. CONCLUSIONS • Four pathogenic genetic changes and two UVs detected in cohort of 21 patients >> mutation pick up rate of 28.6%. • No large genomic rearrangements detected by MLPA analysis of 18 PKP2 probes and 7 DSP probes and 3 probes each for JUP, TGFß3 and RYR2 genes. • The mean age of disease onset in patients with identified PKP2 sequence variant was 32 years (22-52 years) as opposed to 39 years (7-63) in patients without a PKP2 mutation. • As expected no specific G/P correlations were found in this study. • Variable phenotypical expression of the same PKP2 mutation within a family. • July 2008 – launch of PKP2 screening service in Aberdeen.

  21. FUTURE WORK • Improvements to the existing service • 21 patients successfully genotyped since July 2008 (two pathogenic mutations and two UVs potentially pathogenic changes – pick up rate 19.4%). Where do we go from here? • Offer the service to patients in Scotland under the Consortium arrangements. • Improve the resolution of the MLPA analysis and implement MLPA testing in the routine service. • Develop mutation screening of DSG2 gene to increase mutation detection rate in patients with suspected ARVD/C diagnosis (cDNA experiments). • Prepare a gene dossier for ARVD/C genetic testing.

  22. FUTURE WORK • Improvements to the existing service • 21 patients successfully genotyped since July 2008 (two pathogenic mutations and two UVs potentially pathogenic changes – pick up rate 19.4%). Where do we go from here? • Offer the service to patients in Scotland under the Consortium arrangements. • Improve the resolution of the MLPA analysis and implement MLPA testing in the routine service. • Develop mutation screening of DSG2 gene to increase mutation detection rate in patients with suspected ARVD/C diagnosis (cDNA experiments). • Prepare a gene dossier for ARVD/C genetic testing.

  23. REFERENCES Dalal D, Molin LH, Piccini J, Tichnell C, James C, Bomma C, Prakasa K, Towbin JA, Marcus FI, Spevak PJ, Bluemke DA, Abraham T, Russell SD, Calkins H and Judge DO (2006b). Clinical features of arrhythmogenic right ventricular dysplasia/cardiomyopathy associated with mutations in Plakophilin-2. Circulation, 113:1641-1649 Fontaine G, Frank R, Vedel J, Grosgogeat Y, Cabrol C, Facquet J (1977). Stimulation studies and epicardial mapping in ventricular tachycardia: study of mechanisms and selection for surgery. In: Kulbertus HE (eds) Reentrant Arrhythmias. MTP Publishing, Lancaster, 334–350 Gerull B, Heuser A, Wichter T, Paul M, Basson CT, McDermott DA, Lerman BB, Markowitz SM, Ellinor PT, MacRae CA, Peters S, Grossmann KS, Michely B, Sasse-Klaassen S, Birchmeier W, Dietz R, Breithardt G, Schulze-Bahr E, Thierfelder L (2004). Mutations in the desmosomal protein plakophilin-2 are common in arrhythmogenic right ventricular cardiomyopathy. Nature Genet., 36: 1162-1164 McKenna W, Thiene G, Nava A, et al. Diagnosis of arrhythmogenic right ventricular dysplasia/cardiomyopathy (1994). Br Heart J., 71: 215–218 Nava A, Bauce B, Basso C, Muriago M, Rampazzo A, Villanova C, Daliento L, Buja G, Corardo D, Danielli GA, Thiene G (2000). Clinical profile and long-term follow up of 37 families with right ventricular cardiomyopathy. J Am Coll Cardiol., 36:2226-2233 Nava A, Thiene G, Canciani B, Scognamiglio R, Daliento L, Buja GF, Martini B, Stritoni P, Fasoli G (1988). Familial occurrence of right ventricular dysplasia: a study involving nine families. J Am Coll Cardiol. 12:1222– 1228 Peters S (2006) Advances in the diagnostic management of arrhythmogenic right ventricular dysplasia–cardiomyopathy. Int. J. Cardiol. 113: 4-11 Thiene G, Nava A, Corrado D, Rossi L, Pennelli N (1988). Right ventricular cardiomyopathy and sudden death in young people. N Engl J Med., 318:129–133. van der Smagt JJ, Coc MG, Nelen MR, van Tintelen JP, Entius MM, Wiesfeld AC, van gelder IC, de Jong GJ, Doevendans P, Hauer RN (2007) Large genomic deletions in plakophilin-2 are a rare cause of ARVD/C and ARVD/C-like disease. Genetics and genomics of Heart Failure. Circulation 116:II_604 (Abstract). van Tintelen JP et al (2006). Plakophilin-2 mutations are the major determinant of familial arrhythmogenic right ventricular dysplasia/cardiomyopathy. Circulation, 113:1650–1658.

  24. ACKNOWLEDGEMENTS Everyone in the Aberdeen laboratory for their support during both carrying out the experiments and writing up this project. Dawn O’Sullivan Stephen Tennant Dr Christine Bell Caroline Clark Dr Kevin Kelly Dr John Dean

  25. Thank you…

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