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Candidate gene approach to identifying rare genetic variants associated with lone atrial fibrillation.

ABSTRACT: Rare variants in candidate atrial fibrillation (AF) genes have been associated with AF in small kindreds. The extent to which such polymorphisms contribute to AF is unknown.The purpose of this study was to determine the spectrum and prevalence of rare amino acid coding (AAC) variants in candidate AF genes in a large cohort of unrelated lone AF probands.We resequenced 45 candidate genes in 303 European American (EA) lone AF probands (186 lone AF probands screened for each gene on average [range 89-303], 63 screened for all) identified in the Vanderbilt AF Registry (2002-2012). Variants detected were screened against 4300 EAs from the Exome Sequencing Project (ESP) to identify very rare (minor allele frequency ?0.04%) AAC variants and these were tested for AF co-segregation in affected family members where possible.Median age at AF onset was 46.0 years [interquartile range 33.0-54.0], and 35.6% had a family history of AF. Overall, 63 very rare AAC variants were identified in 60 of 303 lone AF probands, and 10 of 19 (52.6%) had evidence of co-segregation with AF. Among the 63 lone AF probands who had 45 genes screened, the very rare variant burden was 22%. Compared with the 4300 EA ESP, the proportion of lone AF probands with a very rare AAC variant in CASQ2 and NKX2-5 was increased 3-5-fold (P <.05).No very rare AAC variants were identified in ~80% of lone AF probands. Potential reasons for the lack of very rare AAC variants include a complex pattern of inheritance, variants in as yet unidentified AF genes or in noncoding regions, and environmental factors.

SUBMITTER: Weeke P

PROVIDER: S-EPMC3947369 | biostudies-literature | 2014 Jan

REPOSITORIES: biostudies-literature

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Candidate gene approach to identifying rare genetic variants associated with lone atrial fibrillation.

Weeke Peter P Parvez Babar B Blair Marcia M Short Laura L Ingram Christie C Kucera Gayle G Stubblefield Tanya T Roden Dan M DM Darbar Dawood D

Heart rhythm 20131010 1

<h4>Background</h4>Rare variants in candidate atrial fibrillation (AF) genes have been associated with AF in small kindreds. The extent to which such polymorphisms contribute to AF is unknown.<h4>Objective</h4>The purpose of this study was to determine the spectrum and prevalence of rare amino acid coding (AAC) variants in candidate AF genes in a large cohort of unrelated lone AF probands.<h4>Methods</h4>We resequenced 45 candidate genes in 303 European American (EA) lone AF probands (186 lone A ...[more]

PMID: 24120998

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Project description:ImportanceAlthough rare variants in cardiac ion channels, transcription factors, and myocardial structural proteins are associated with early-onset atrial fibrillation (AF) in White individuals of European descent, it remains unclear whether genetic variation also contributes to the cause of AF in those of minority ethnicity.ObjectivesTo assess the prevalence of rare and novel pathogenic variants in candidate genes in ethnic minority probands with early-onset AF and determine genotype-phenotype associations.Design, setting, and participantsIn this cohort, family-based study, probands of African and Hispanic descent with early-onset AF (defined as AF occurring in individuals aged ≤66 years) prospectively enrolled in a clinical and genetic biorepository underwent sequencing of 60 candidate genes. Recruitment took place from July 1, 2015, to June 30, 2019. Data were analyzed from February 1 to February 28, 2020.ExposuresRare and novel variants categorized as pathogenic or likely pathogenic.Main outcomes and measuresThe prevalence of rare and novel pathogenic variants in African American and Hispanic/Latinx probands with early-onset AF and genotype-phenotype associations.ResultsAmong 227 probands with early-onset AF, mean (SD) age at onset of AF was 51.0 (9.9) years, 132 probands (58.1%) were men, 148 (65.2%) were African American, and 79 (34.8%) were Hispanic/Latinx. A family history of AF was verified in 24 probands with early-onset AF (10.6%). Sequencing 60 candidate genes identified 53 (23 rare and 30 novel) variants with 16 of the 227 (7.0%) probands harboring likely pathogenic (43.8%) or pathogenic (56.2%) variants, with most loss-of-function variants in TTN, the gene encoding the sarcomeric protein titin (46.7%). In 6 families with more than 2 affected members, variants of unknown significance in sodium channel (SCN10A), potassium channel (KCNE5), sarcomeric proteins (MYH6 and TTN), and atrial natriuretic peptide (NPPA) cosegregated with AF.Conclusions and relevanceIn this study, likely pathogenic and pathogenic variants were identified, with most loss-of-function variants in TTN, that increase susceptibility to early-onset AF in African American and Hispanic/Latinx individuals. These findings provide further understanding toward molecular phenotyping of AF and suggest novel mechanism-based therapeutic approaches for this common arrhythmia in ethnic minority groups.

Project description:RationaleAtrial fibrillation (AF) is encountered rarely in pregnancy. Management of maternal AF is challenging as it poses a threat to both maternal and fetal well-being.Patient concernsWe report a case of a 35 weeks pregnant woman who presented in emergency with sudden-onset palpitations and mild shortness of breath with no personal/family history of cardiac diseases.DiagnosesPatient's pulse was irregularly irregular with an average rate of 179 beats per minute. The obstetric examination was normal.DiagnosisHigh-sensitive cardiac troponin T (hs-cTnT) was elevated. The 12 lead electrocardiogram (ECG) confirmed AF. The obstetric ultrasound, electronic fetal heart rate (EFHR) trace, and maternal echocardiography were normal.InterventionsThe patient was admitted under joint cardiology and obstetric care and monitored with continuous telemetry. She was commenced on a therapeutic dose of low-molecular weight heparin (LMWH) and intravenous fluid. She received a single 200 Joule synchronized direct current (DC) shock under general anesthesia in operation theater, which reverted the rhythm back to normal. EFHR monitoring was normal pre- and post-DC cardioversion. We acknowledge the unwise use of therapeutic dose of LMWH before DC cardioversion (DCCV) because of a potential need for emergency cesarean delivery for maternal and/or fetal compromise.OutcomeThe patient remained well and in sinus rhythm after cardioversion. She was discharged home the following day on Flecainide (anti-arrhythmic) and therapeutic dose of low molecular weight heparin (LMWH) and followed up in outpatient clinics frequently. She had a baby at term and received prophylactic LMWH for 10 days post-cesarean. She was discharged from cardiology clinic when she was 10 weeks postnatal, and Flecainide was discontinued.LessonsWe are reporting this case because of the rarity of the condition and successful use of DCCV for treating maternal AF. High-sensitive cardiac troponin T (hs-cTnT) level is a useful laboratory indicator to gauge the severity of AF in pregnancy. We emphasize to make the arrangements for EFHR monitoring and potential cesarean delivery and advocate cautious use of thromboprophylaxis while planning for electrical cardioversion (ECV) for maternal AF.

Project description:ImportanceAtrial fibrillation (AF) has a substantial genetic component. The importance of polygenic risk is well established, while the contribution of rare variants to disease risk warrants characterization in large cohorts.ObjectiveTo identify rare predicted loss-of-function (pLOF) variants associated with AF and elucidate their role in risk of AF, cardiomyopathy (CM), and heart failure (HF) in combination with a polygenic risk score (PRS).Design, setting, and participantsThis was a genetic association and nested case-control study. The impact of rare pLOF variants was evaluated on the risk of incident AF. HF and CM were assessed in cause-specific Cox regressions. End of follow-up was July 1, 2022. Data were analyzed from January to October 2023. The UK Biobank enrolled 502 480 individuals aged 40 to 69 years at inclusion in the United Kingdom between March 13, 2006, and October 1, 2010. UK residents of European ancestry were included. Individuals with prior diagnosis of AF were excluded from analyses of incident AF.ExposuresRare pLOF variants and an AF PRS.Main outcomes and measuresRisk of AF and incident HF or CM prior to and subsequent to AF diagnosis.ResultsA total of 403 990 individuals (218 489 [54.1%] female) with a median (IQR) age of 58 (51-63) years were included; 24 447 were diagnosed with incident AF over a median (IQR) follow-up period of 13.3 (12.4-14.0) years. Rare pLOF variants in 6 genes (TTN, RPL3L, PKP2, CTNNA3, KDM5B, and C10orf71) were associated with AF. Of these, TTN, RPL3L, PKP2, CTNNA3, and KDM5B replicated in an external cohort. Combined with high PRS, rare pLOF variants conferred an odds ratio of 7.08 (95% CI, 6.03-8.28) for AF. Carriers with high PRS also had a substantial 10-year risk of AF (16% in female individuals and 24% in male individuals older than 60 years). Rare pLOF variants were associated with increased risk of CM both prior to AF (hazard ratio [HR], 3.13; 95% CI, 2.24-4.36) and subsequent to AF (HR, 2.98; 95% CI, 1.89-4.69).Conclusions and relevanceRare and common genetic variation were associated with an increased risk of AF. The findings provide insights into the genetic underpinnings of AF and may aid in future genetic risk stratification.

Dataset Information

Candidate gene approach to identifying rare genetic variants associated with lone atrial fibrillation.

Publications

Candidate gene approach to identifying rare genetic variants associated with lone atrial fibrillation.

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