Postmortem long QT syndrome genetic testing for sudden unexplained death in the young.
ABSTRACT This study sought to determine the spectrum and prevalence of long QT syndrome (LQTS)-associated mutations in a large cohort of autopsy-negative sudden unexplained death (SUD).
Potentially heritable arrhythmia syndromes may explain a significant proportion of SUD in the young. Here, comprehensive postmortem LQTS genetic testing was performed in a cohort of SUD cases.
From September 1998 to March 2004, 49 cases of SUD (30 male patients, average age at death 14.2 +/- 10.9 years) were referred by medical examiners/coroners to Mayo Clinic's Sudden Death Genomics Laboratory. Using polymerase chain reaction, denaturing high-performance liquid chromatography, and direct DNA sequencing, open reading frame/splice site mutational analysis was conducted for all 8 genes implicated in the pathogenesis of either LQTS (LQT1 to LQT6) or multisystem disorders involving either QT or QU prolongation.
Ten LQTS-associated mutations (4 novel) were discovered in 10 SUD cases (20%, 8 female patients, average age at death 18.0 +/- 11.8 years). The LQTS susceptibility mutations LQT1 (5), LQT2 (3), and LQT3 (2) were far more common among women (8 of 18, 44%) than men (2 of 30, 6.7%, p < 0.008). The activities at the time of SUD included sleep (5), exertion (2), auditory arousal (1), and undetermined (2). Sudden death was the sentinel event in two-thirds of the cases.
In this cardiac channel-focused molecular autopsy investigation of SUD, over one-third of decedents harbored a putative cardiac channel mutation: 7 previously reported to host mutations in the RyR2-encoded calcium release channel and now 10 with LQTS susceptibility mutations. Accordingly, postmortem cardiac channel genetic testing should be pursued in the evaluation of autopsy-negative SUD.
Article: Familial evaluation in catecholaminergic polymorphic ventricular tachycardia: disease penetrance and expression in cardiac ryanodine receptor mutation-carrying relatives.[show abstract] [hide abstract]
ABSTRACT: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmia syndrome associated with mutations in the cardiac ryanodine receptor gene (Ryr2) in the majority of patients. Previous studies of CPVT patients mainly involved probands, so current insight into disease penetrance, expression, genotype-phenotype correlations, and arrhythmic event rates in relatives carrying the Ryr2 mutation is limited. One-hundred sixteen relatives carrying the Ryr2 mutation from 15 families who were identified by cascade screening of the Ryr2 mutation causing CPVT in the proband were clinically characterized, including 61 relatives from 1 family. Fifty-four of 108 antiarrhythmic drug-free relatives (50%) had a CPVT phenotype at the first cardiological examination, including 27 (25%) with nonsustained ventricular tachycardia. Relatives carrying a Ryr2 mutation in the C-terminal channel-forming domain showed an increased odds of nonsustained ventricular tachycardia (odds ratio, 4.1; 95% CI, 1.5-11.5; P=0.007, compared with N-terminal domain) compared with N-terminal domain. Sinus bradycardia was observed in 19% of relatives, whereas other supraventricular dysrhythmias were present in 16%. Ninety-eight (most actively treated) relatives (84%) were followed up for a median of 4.7 years (range, 0.3-19.0 years). During follow-up, 2 asymptomatic relatives experienced exercise-induced syncope. One relative was not being treated, whereas the other was noncompliant. None of the 116 relatives died of CPVT during a 6.7-year follow-up (range, 1.4-20.9 years). Relatives carrying an Ryr2 mutation show a marked phenotypic diversity. The vast majority do not have signs of supraventricular disease manifestations. Mutation location may be associated with severity of the phenotype. The arrhythmic event rate during follow-up was low.Circulation Arrhythmia and Electrophysiology 07/2012; 5(4):748-56. · 6.46 Impact Factor
Article: HRS/EHRA expert consensus statement on the state of genetic testing for the channelopathies and cardiomyopathies: this document was developed as a partnership between the Heart Rhythm Society (HRS) and the European Heart Rhythm Association (EHRA).Europace 08/2011; 13(8):1077-109. · 1.98 Impact Factor
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ABSTRACT: Sudden Cardiac Death (SCD) is a major and tragic complication of a number of cardiovascular diseases. While in the older populations, SCD is most frequently caused by underlying coronary artery disease and heart failure, in those aged under 40 years, the causes of SCD commonly include genetic disorders, such as inherited cardiomyopathies and primary arrhythmogenic diseases. As part of the evaluation of families in which SCD has occurred, the role of genetic testing has evolved as an important feature in both establishing an underlying diagnosis and in screening at-risk family relatives. Specifically, in cases where no definitive cause is identified at postmortem, i.e. Sudden Unexpected Death (SUD), the "molecular autopsy" has emerged as a key process in the investigation of the cause of death. The combination of clinical and genetic evaluation of families in which SUD has occurred provides a platform for early initiation of therapeutic and prevention strategies, with the ultimate goal to reduce sudden death among the young in our communities.Heart rhythm: the official journal of the Heart Rhythm Society 08/2011; 9(1):145-50. · 4.56 Impact Factor