Post-mortem genetic testing in sudden cardiac death and genetic screening of relatives at risk: lessons learned from a Czech pilot multidisciplinary study.

Sudden cardiac death (SCD) might have an inherited cardiac condition background. Genetic testing supports post-mortem diagnosis and screening of relatives at risk. Our aim is to determine the feasibility of a Czech national collaboration group and to establish the clinical importance of molecular autopsy and family screening. From 2016 to 2021, we have evaluated 100 unrelated SCD cases (71.0% males, age: 33.3 (12.8) years). Genetic testing was performed by next-generation sequencing utilizing a panel of 100 genes related to inherited cardiac/aortic conditions and/or whole exome sequencing. According to autopsy, cases were divided into cardiomyopathies, sudden arrhythmic death syndrome, sudden unexplained death syndrome, and sudden aortic death. We identified pathogenic/likely pathogenic variants following ACMG/AMP recommendations in 22/100 (22.0%) of cases. Since poor DNA quality, we have performed indirect DNA testing in affected relatives or in healthy parents reaching a diagnostic genetic yield of 11/24 (45.8%) and 1/10 (10.0%), respectively. Cardiological and genetic screening disclose 83/301 (27.6%) relatives at risk of SCD. Genetic testing in affected relatives as starting material leads to a high diagnostic yield offering a valuable alternative when suitable material is not available. This is the first multidisciplinary/multicenter molecular autopsy study in the Czech Republic which supports the establishment of this type of diagnostic tests. A central coordinator and proper communication among centers are crucial for the success of a collaboration at a national level.

Burden of sudden cardiac death in persons aged 1-40 years in the Czech Republic.

OBJECTIVES: The aim of the study was to ascertain the incidence, circumstances and causes of sudden cardiac death in persons aged 1-40 years in the Czech Republic. METHODS: De-identified autopsy reports of all individuals who died suddenly between the ages of 1-40 years during the period 2014-2019 inclusive in a selected area of the Czech Republic were analysed retrospectively. Persons with substantial cardiovascular pathology defined by histopathological criteria and those with a negative autopsy were included in the study. The latter were designated as sudden arrhythmic death syndrome. RESULTS: In total, 245 sudden cardiac death cases were identified resulting in an incidence rate of 2.4/100,000 person-years. Among the deceased, we found an enormous gender gap with men representing 81% of cases. More than 80% of deaths occurred during everyday activities or sleep, whereas only 7% were sports-related. The most common cause of death was coronary artery disease detected in 38%, which was followed by cardiomyopathies in 15%, sudden arrhythmic death syndrome in 12%, left ventricular hypertrophy in 10%, and congenital heart defects in 7%. CONCLUSIONS: Coronary artery disease is the predominant cause of sudden cardiac death in the young population of the Czech Republic. Hence, effective preventive measures targeted at the reduction of risk factors associated with early coronary artery disease should be reinforced. The second most prevalent cause in our population are potentially heritable heart conditions such as cardiomyopathies and sudden arrhythmic death syndrome. This fact has already prompted the introduction of molecular autopsy and cardiogenetic care for relatives in the Czech Republic.

Contribution of dihydropyrimidinase gene alterations to the development of serious toxicity in fluoropyrimidine-treated cancer patients.

PURPOSE: Decreased 5-fluorouracil catabolism has been considered a major factor contributing to fluoropyrimidine (FP)-related toxicity. Alterations in the dihydropyrimidine dehydrogenase gene coding for the first and rate-limiting enzyme of FP catabolic pathway could explain toxicity in only a limited proportion of FP-treated patients. The importance of gene variants in dihydropyrimidinase (DPYS) coding for subsequent catabolic enzyme of FP degradation is not fully understood. METHODS: We performed genotyping of DPYS based on denaturing high-performance liquid chromatography in 113 cancer patients including 67 with severe FP-related toxicity and 46 without toxicity excellently tolerating FPs treatment. RESULTS: We detected nine DPYS variants including four located in non-coding sequence (c.-1T>C, IVS1+34C>G, IVS1-58T>C, and novel IVS4+11G>T), four silent (c.15G>A, c.216C>T, and novel c.105C>T and c.324C>A), and one novel missense variant c.1441C>T (p.R481W). All novel alterations were detected once only in patients without toxicity. The c.-1T>C and IVS1-58T>C variants were found to modify the risk of toxicity. The CC carriers of the c.-1C alleles were at higher risk of mucositis (OR = 4.13; 95% CI = 1.51-11.31; P = 0.006) and gastrointestinal toxicity (OR = 3.54; 95% CI = 1.59-7.88; P = 0.002), whereas the presence of the IVS1-58C allele decreased the risk of gastrointestinal toxicity (OR = 0.4; 95% CI = 0.17-0.93; P = 0.03) and leucopenia (OR = 0.29; 95% CI = 0.08-1.01; P = 0.05). CONCLUSIONS: Our results indicate that missense and nonsense variants in DPYS are infrequent, however, the development of serious primarily gastrointestinal toxicity could be influenced by non-coding DPYS sequence variants c.-1T>C and IVS1-58T>C.