Comparison of variant detection rate in genes between two cohorts of Czech living patients versus victims of sudden cardiac death with clinical / post mortem diagnosis of non-ischemic cardiomyopathy

Introduction Hereditary cardiomyopathy is associated with an increased risk of ventricular arrhythmia and sudden cardiac death (SCD). Genetic stratification substantiates risk assessment and enables the primary prevention of SCD in relatives at risk. We have analyzed the genetic aetiology of SCD in a representative Czech cohort with post mortem diagnosis of various forms of cardiomyopathy and compared it to living cases with these cardiac disorders. Patients and methods Between 2018 and 2019, altogether 47 victims of SCD with post mortem diagnosis of hypertrophic- (HCM; 18/47), arrhythmogenic- (ACM; 19/47) and dilated cardiomyopathy (DCM; 10/47) were identified. Concurrently, genetic testing was performed in 114 living patients (HCM 54/114, ACM 22/114, DCM 38/114). Genetic counselling and cardiologic examination had been carried out in first-degree relatives in all patients/SCD victims. Massively parallel sequencing (MiSeq platform; Illumina.com) was utilized for a custom-made panel comprising 100 candidate genes (Sophia Genetics, Switzerland). The presence of pathogenic variants was validated by Sanger DNA sequencing and through family segregation analyses. Results The causative detection rate (according to ACMG.net classes 4 or 5) in SCD victims with DCM was 60% (6/10) and in living patients with DCM 47.4% (18/38). Variants in TTN, RBM20, DES and FLNC (mainly truncating variants) prevailed in both groups. The detection rate in ACM was 5% (1/19 in SCN5A gene) in SCD victims and 31.8% (7/22) in living patients. Interestingly, the most prevalent mutated gene PKP2 in living patients was not detected in SCD victims. The detection rate in SCD victims with post mortem diagnosis of HCM was 16% (3/18) and in living patients 35% (19/54). The most prevalent gene was MYBPC3 in both groups, while PRKAG2 was detected in one SCD victim and in one living case who survived cardiac arrest. Conclusion Post-mortem genetic analysis in DCM yields a high detection rate and allows potentially effective primary prevention of SCD in relatives at risk. In contrast, the molecular autopsy of HCM and ACM renders a much lower yield which is below the mutation detection rate in living phenotype positive individuals. The results help to improve the genetic counselling in affected families in Czech Republic. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Ministry of Health of the Czech Republic