Search

Objectives: This study determined if radical plakophilin-2 (PKP2) variants might underlie some cases of clinically diagnosed catecholaminergic polymorphic ventricular tachycardia (CPVT) and exercise-associated, autopsy-negative sudden unexplained death in the young (SUDY)., Background: Pathogenic variants in PKP2 cause arrhythmogenic right ventricular cardiomyopathy (ARVC). Recently, a cardiomyocyte-specific PKP2 knockout mouse model revealed that loss of PKP2 markedly reduced expression of genes critical in intracellular calcium handling. The mice with structurally normal hearts exhibited isoproterenol-triggered polymorphic ventricular arrhythmias that mimicked CPVT., Methods: A PKP2 gene mutational analysis was performed on DNA from 18 unrelated patients (9 males; average age at diagnosis: 19.6 ± 12.8 years) clinically diagnosed with CPVT but who were RYR2-, CASQ2-, KCNJ2-, and TRDN-negative, and 19 decedents with SUDY during exercise (13 males; average age at death: 14 ± 3 years). Only radical (i.e., frame-shift, canonical splice site, or nonsense) variants with a minor allele frequency of ≤0.00005 in the genome aggregation database (gnomAD) were considered pathogenic., Results: Radical PKP2 variants were identified in 5 of 18 (27.7%) CPVT patients and 1 of 19 (5.3%) exercise-related SUDY cases compared with 96 of 138,632 (0.069%) individuals in gnomAD (p = 3.1 × 10 -13 ). Cardiac imaging or autopsy demonstrated a structurally normal heart in all patients at the time of their CPVT diagnosis or sudden death., Conclusions: Our data suggested that the progression of the PKP2-dependent electropathy can be independent of structural perturbations and can precipitate exercise-associated sudden cardiac arrest or sudden cardiac death before the presence of overt cardiomyopathy, which clinically mimics CPVT, similar to the PKP2 knockout mouse model. Thus, CPVT and SUDY genetic test panels should now include PKP2., (Copyright © 2019 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objective: The Latvian arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD-C) registry was established to determine the genetic background of ARVD-C for analyzing discovered genetic variation frequencies in the European and Latvian populations., Methods: In total, 38 patients with suspected ARVD-C were selected. The clinical parameters were defined according to the ARVD-C guidelines, PKP2 and DSG2 gene analysis was performed using the Sanger sequencing. Additionally, large deletions/duplications were analyzed using the multiplex ligation-dependent probe amplification (MLPA) analysis., Results: Twenty symptomatic patients were enrolled in the study. Typical ARVD abnormalities were found in electrocardiography for 10 (50%) patients, in Holter monitoring for 19 (95%), in transthoracic echocardiography for 20 (100%), and in cardiac magnetic resonance for 6 (30%). Different benign genetic variations were found. Three novel, unregistered, possibly benign variations were found in the PKP2 gene: c.2489+131G>A, c.2489+72delA, and c.1035-5T>C and three in the DSG2 gene: c.404G>A, c.1107G>A, and c.379-15A>G. Two genetic variations in the PKP2 gene: c.1592T>G, c.2489+1G>A are possibly pathogenic. For the first time, variation c.1592T>G, has been discovered in the homozygote form. Using the MLPA analysis, large deletions or duplications were not found., Conclusion: The prevalence of the majority of non-pathological genetic variations is similar in the Latvian ARVD-C patients and the European population. Possibly, pathogenic variations were found only in 10% of our registry patients, which could mean that PKP2 and DSG2 are not the most commonly affected genes in the Latvian population.

Objective: Arrhythmogenic cardiomyopathy (ACM) is not an uncommon cause of cardiac morbidity in Kashmir valley. This study was designed to document various clinical features and to sequence exons 11 and 12 of plakophilin 2 (PKP2) gene in these patients., Methods: ACM patients who attended cardiology outpatient department of our institute from January 2014 to April 2015 were included in the study. Their records were reviewed. Controls were randomly selected, who had no history or family history of cardiac illness and had a normal cardiac examination. A blood sample was also taken from both the groups for sequencing of exon 11 and 12 of PKP2 gene. ACM patients were followed up until July 2016., Results: Eleven ACM patients and seven controls were included in the study. Most common mode of presentation was ventricular tachycardia (VT). Two patients had left ventricular (LV) systolic dysfunction. One patient had a splice site mutation in exon 12 of PKP2 gene and one patient died during follow-up. One of the controls had an intronic variation that has no pathogenic significance vis-à-vis ACM., Conclusion: Our study describes various clinical parameters in ACM patients and a recessive plakophilin 2 mutation after a limited PKP2 gene sequencing., (Copyright © 2017. Published by Elsevier B.V.)

Increased left ventricular mass (LVM) is an intermediate phenotype for cardiovascular disease (CVD) and a predictor of stroke. Using families from the Dominican Republic, we have previously shown LVM to be heritable and found evidence for linkage to chromosome 12p11. Our current study aimed to further characterize the QTL by sequencing the 1 LOD unit down region in 10 families from the Dominican Republic with evidence for linkage to LVM. Within this region, we tested 5477 common variants [CVs; minor allele frequency (MAF) ≥5%] using the Quantitative Transmission-Disequilibrium Test (QTDT). Gene-based analyses were performed to test rare variants (RVs; MAF < 5%) in 181 genes using the family-based sequence kernel association test. A sample of 618 unrelated Dominicans from the Northern Manhattan Study (NOMAS) and 12 Dominican families with Exome Array data were used for replication analyses. The most strongly associated CV with evidence for replication was rs1046116 (Discovery families P = 9.0 × 10 -4 ; NOMAS P = 0.03; replication families P = 0.46), a missense variant in PKP2 In nonsynonymous RV analyses, PKP2 was one of the most strongly associated genes ( P = 0.05) with suggestive evidence for replication in NOMAS ( P = 0.05). PKP2 encodes the plakophilin 2 protein and is a desmosomal gene implicated in arrythmogenic right ventricular cardiomyopathy and recently in arrhythmogenic left ventricular cardiomyopathy, which makes PKP 2 an excellent candidate gene for LVM. In conclusion, sequencing of our previously reported QTL identified common and rare variants within PKP2 to be associated with LVM. Future studies are necessary to elucidate the role these variants play in influencing LVM., (Copyright © 2018 N. D. Dueker et al.)

Background: The clinical profile of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) patients with late presentation is unknown., Objective: The purpose of this study was to characterize the genotype, cardiac phenotype, and long-term outcomes of ARVC/D patients with late presentation (age ≥50 years at diagnosis)., Methods: Five hundred two patients with an ARVC/D diagnosis from Johns Hopkins and Utrecht Registries were studied and long-term clinical outcomes ascertained., Results: Late presentation was seen in 104 patients (21%; 38% PKP2 carriers); 3% were ≥65 years at diagnosis. Sustained ventricular tachycardia was the major (43%) mode of presentation in patients with late presentation, whereas cardiac syncope was infrequent (P <.001). Those with late presentation were significantly less likely to harbor a known pathogenic mutation (53%; P = .005), have less precordial T-wave repolarization changes (P <.001), and have lower ventricular ectopy burden (P = .026). Over median 6-year follow-up, 68 patients with late presentation (65%) experienced sustained ventricular arrhythmias, with similar arrhythmia-free survival at 5-year follow up (P = .48). Left ventricular dysfunction and heart failure were seen in 24 (32%) and 15 patients (14%), respectively, without need for cardiac transplantation. In the late presentation cohort, male sex, pathogenic mutation, right ventricular structural disease, lack of family history, and electrophysiologic study inducibility were associated with increased arrhythmic risk., Conclusion: One-fifth of all ARVC/D patients present after age 50 years, often with sustained ventricular tachycardia, and are less likely to have prior syncope, ECG changes, ventricular ectopy, or identifiable pathogenic mutation. In ARVC/D, late presentation does not confer a benign prognosis and is associated with high arrhythmic risk., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

Aims: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a disease mainly caused by desmosome gene mutations. The genetic culprit, however, remains elusive in ∼50% of ARVC patients. One of the reasons for missing genetic abnormalities is the difficulty in detecting large deletions/duplications, which are called as copy number variation (CNV) by the Sanger sequencing method. This study aimed to identify CNVs in PKP2 and a part of other desmosome genes in ARVC patients., Methods and Results: The study cohort consisted of 71 ARVC probands who were diagnosed as definite or borderline cases based on 2010 Task Force Criteria. Among them, 32 (45%) carried at least one mutation in desmosome genes detected by the Sanger method. Using the multiplex ligation-dependent probe amplification method, we identified a male proband (1.4%) with a complete deletion of all PKP2 coding exons. He was 31 years old and showed exercise-induced sustained ventricular tachycardia with superior axis and left bundle-branch block pattern. His cardiac magnetic resonance imaging and computed tomography showed right ventricular dilatation and reduced ejection fraction. His 12-lead electrocardiogram showed T-wave inversion in V1-V3, and late potentials were positive, indicating definite ARVC. To confirm the precise location of the deletion, we performed relative quantitative PCR. We found complete deletion of both SYT10 and ALG10 located in 3' of PKP2; the total deletion size was at least 1.23 Mb., Conclusion: Screening for CNVs in desmosome genes is useful to identify the genetic basis of disease in clinically suspected ARVC patients., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.)

Left ventricular noncompaction cardiomyopathy (LVNC) is a clinically heterogeneous disorder characterized by a trabecular meshwork and deep intertrabecular myocardial recesses that communicate with the left ventricular cavity. Several genetic causes of LVNC have been reported, with variable modes of inheritance, including autosomal dominant and X-linked inheritance, but relatively few responsible genes have been identified. A NGS workflow, based on a panel of 95 genes developed for sequencing most prevalent sudden cardiac death-causing genes, was used to make a rapid and costless molecular diagnosis in two siblings with a severe noncompaction cardiomyopathy starting prenatally and leading to rapid cardiac failure. For the first time, a total homozygous PKP2 deletion was identified. This molecular defect was further confirmed by MLPA and array-comparative genomic hybridization (CGH). Heterozygous PKP2 mutations are usually reported in a significant proportion of Arrhythmogenic Right Ventricular Cardiomyopathy cases. Our results show, for the first time, the involvement of PKP2 in severe cardiomyopathy with ventricular non compaction., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Canine atopic dermatitis (CAD) is a chronic inflammatory skin disease triggered by allergic reactions involving IgE antibodies directed towards environmental allergens. We previously identified a ~1.5 Mb locus on canine chromosome 27 associated with CAD in German shepherd dogs (GSDs). Fine-mapping indicated association closest to the PKP2 gene encoding plakophilin 2., Results: Additional genotyping and association analyses in GSDs combined with control dogs from five breeds with low-risk for CAD revealed the top SNP 27:19,086,778 (p = 1.4 × 10(-7)) and a rare ~48 kb risk haplotype overlapping the PKP2 gene and shared only with other high-risk CAD breeds. We selected altogether nine SNPs (four top-associated in GSDs and five within the ~48 kb risk haplotype) that spanned ~280 kb forming one risk haplotype carried by 35 % of the GSD cases and 10 % of the GSD controls (OR = 5.1, p = 5.9 × 10(-5)), and another haplotype present in 85 % of the GSD cases and 98 % of the GSD controls and conferring a protective effect against CAD in GSDs (OR = 0.14, p = 0.0032). Eight of these SNPs were analyzed for transcriptional regulation using reporter assays where all tested regions exerted regulatory effects on transcription in epithelial and/or immune cell lines, and seven SNPs showed allelic differences. The DNA fragment with the top-associated SNP 27:19,086,778 displayed the highest activity in keratinocytes with 11-fold induction of transcription by the risk allele versus 8-fold by the control allele (pdifference = 0.003), and also mapped close (~3 kb) to an ENCODE skin-specific enhancer region., Conclusions: Our experiments indicate that multiple CAD-associated genetic variants located in cell type-specific enhancers are involved in gene regulation in different cells and tissues. No single causative variant alone, but rather multiple variants combined in a risk haplotype likely contribute to an altered expression of the PKP2 gene, and possibly nearby genes, in immune and epithelial cells, and predispose GSDs to CAD.

Epsilon waves are a major criterion for the diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC) but are an insensitive sign. Recently, exercise testing has been shown to uncover epsilon waves in asymptomatic patients carrying mutations in the PKP2 gene. We describe a case of an asymptomatic carrier of a mutation in the DSP gene who had a normal baseline electrocardiogram and an exercise-induced epsilon wave. This finding suggests that exercise testing may be valuable for the diagnosis of ARVC and that exercise-induced epsilon waves may be found in various genetic subtypes of this disease., (Copyright © 2015 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

Arrhythmogenic right ventricular cardiomyopathy is an inherited cardiac entity characterized by right ventricular, or biventricular, fibrofatty replacement of myocardium. Structural alterations may lead to sudden cardiac death, mainly in young males during exercise. Autosomal dominant pattern of inheritance is reported in most parts of pathogenic genetic variations identified. Currently, 13 genes have been associated with the disease but nearly 40 % of clinically diagnosed cases remain without a genetic diagnosis. New genetic technologies allow further genetic analysis, generating a significant amount of genetic data in novel genes, which is often classified as of ambiguous significance. We focus on genetic advances of arrhythmogenic right ventricular cardiomyopathy, helping clinicians to interpret and translate genetic data into clinical practice.

The genetic basis of arrhythmogenic right ventricular cardiomyopathy (ARVC) is complex. Mutations in genes encoding components of the cardiac desmosomes have been implicated as being causally related to ARVC. Next-generation sequencing allows parallel sequencing and duplication/deletion analysis of many genes simultaneously, which is appropriate for screening of mutations in disorders with heterogeneous genetic backgrounds. We designed and validated a next-generation sequencing test panel for ARVC using HaloPlex. We used SureDesign to prepare a HaloPlex enrichment system for sequencing of DES, DSC2, DSG2, DSP, JUP, PKP2, RYR2, TGFB3, TMEM43, and TTN from patients with ARVC using a MiSeq instrument. Performance characteristics were determined by comparison with Sanger, as the gold standard, and TruSeq Custom Amplicon sequencing of DSC2, DSG2, DSP, JUP, and PKP2. All the samples were successfully sequenced after HaloPlex capture, with >99% of targeted nucleotides covered by >20×. The sequences were of high quality, although one problematic area due to a presumptive context-specific sequencing error-causing motif located in exon 1 of the DSP gene was detected. The mutations found by Sanger sequencing were also found using the HaloPlex technique. Depending on the bioinformatics pipeline, sensitivity varied from 99.3% to 100%, and specificity varied from 99.9% to 100%. Three variant positions found by Sanger and HaloPlex sequencing were missed by TruSeq Custom Amplicon owing to loss of coverage., (Copyright © 2015 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.)

Background: Although mutations of several genes are associated with arrhythmogenic right ventricular cardiomyopathy (ARVC), the exact correlation between genotype and ventricular arrhythmia features remains unclear. This study was aimed to examine the possible association of the 9 known genes of ARVC with clinical and electrophysiological characteristics., Methods and Results: Ninety subjects diagnosed with ARVC who underwent electrophysiological study were recruited for screening the 9 known ARVC-causing genes. A total of 53 mutations were identified in 57 (63%) subjects. Mutation carriers had more frequent clinical ventricular tachycardia (VT; 89% versus 55%; P<0.001) and negative T waves in V1 to V3 (61% versus 33%; P=0.016). Subjects with plakophilin-2 (PKP2) mutations also had more frequent VT than those without mutations in PKP2. Comparison between subjects with multiple and single mutations showed that syncope occurred more often in the former group (58% versus 24%; P=0.018). VT was significantly more often induced in mutation carriers compared with noncarriers (75% versus 39%; P=0.001), as well as in PKP2 mutation carriers compared with subjects without PKP2 mutations (80% versus 48%; P=0.002). Induced VT with a rate ≥ 200 bpm was more often documented in mutation carriers (88% versus 54%; P=0.013), as well as in PKP2 mutation carriers (91% versus 67%; P=0.041)., Conclusions: Pathogenic gene mutations were found in nearly two thirds of subjects diagnosed with ARVC. Mutation carriers, especially PKP2, had a higher proportion of a history of VT and more inducible fast VT.

Objectives: The aim of this study was to determine if exercise testing could expose a latent electrical substrate of arrhythmogenic right ventricular cardiomyopathy (ARVC) in asymptomatic gene carriers., Background: Management of asymptomatic ARVC gene carriers is challenging because of variable penetrance of disease and the recognition that sudden cardiac death may be the first clinical manifestation., Methods: Exercise-induced abnormalities during exercise treadmill testing (ETT) were initially compared in 60 subjects: 30 asymptomatic ARVC gene carriers and 30 healthy controls. In phase 2 of the study, ETT results of 25 patients with ARVC with histories of sustained ventricular arrhythmia or cardiac arrest were evaluated to determine if ETT abnormalities in asymptomatic gene carriers were common to patients with a malignant electrical form of the disease., Results: Depolarization abnormalities during ETT were found to develop more frequently in asymptomatic gene carriers compared with healthy controls: epsilon waves appeared in 4 of 28 (14%) compared with 0 of 30 (0%) (p = 0.048), premature ventricular contractions in 17 of 30 (57%) compared with 3 of 30 (10%) (p = 0.0003), and new QRS terminal activation duration ≥ 55 ms in 7 of 22 (32%) compared with 2 of 29 (7%) (p = 0.03). Superior axis premature ventricular contractions occurred only in gene carriers. In the second phase of the study, the frequency of these abnormalities was found to be high in patients with symptomatic ARVC: new epsilon waves appeared in 3 of 18 (17%), superior axis premature ventricular contractions in 21 of 25 (84%), and new terminal activation duration ≥ 55 ms in 8 of 12 (67%)., Conclusions: Exercise testing exposes a latent electrical substrate in asymptomatic ARVC gene carriers that is shared by patients with ARVC with histories of ventricular arrhythmia. ETT may be useful in guiding treatment decisions, exercise prescription, and prioritizing medical surveillance in asymptomatic ARVC gene carriers., (Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: The aim of this study was to identify the incremental value and optimal role of cardiac magnetic resonance (CMR) imaging in arrhythmic risk stratification of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C)-associated desmosomal mutation carriers without histories of sustained ventricular arrhythmia., Background: Risk stratification of ARVD/C mutation carriers is challenging., Methods: Sixty-nine patients (mean age 27.0 ± 15.3 years, 42% men) harboring ARVD/C-associated pathogenic mutations (83% plakophilin 2) without prior sustained ventricular arrhythmias were included. Electrocardiographic and 24-h Holter monitoring findings closest to presentation were analyzed for electrical abnormalities per revised task force criteria. CMR studies were done to identify abnormal cardiac structure and function according to the revised task force criteria., Results: Overall, 42 patients (61%) presented with electrical abnormalities on the basis of electrocardiography and Holter monitoring, of whom 20 (48%) had abnormal results on CMR. Only 1 of 27 patients (4%) without electrical abnormalities at initial evaluation had abnormal CMR results. Over a mean follow-up period of 5.8 ± 4.4 years, 11 patients (16%) experienced sustained ventricular arrhythmias, exclusively in patients with both electrical abnormalities (electrocardiography and/or Holter monitoring) and abnormal CMR results., Conclusions: These results suggest that electrical abnormalities on electrocardiography and Holter monitoring precede detectable structural abnormalities in ARVD/C mutation carriers. Therefore, evaluation of cardiac structure and function using CMR is probably not necessary in the absence of baseline electrical abnormalities. Among ARVD/C mutation carriers, the presence of both electrical and CMR abnormalities identifies patients at high risk for events and thus patients who might benefit from prophylactic implantable cardioverter-defibrillator placement., (Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Desmosomes are dynamic junctions between cells that maintain the structural integrity of skin and heart tissues by withstanding shear forces. Mutations in component genes cause life-threatening conditions including arrhythmogenic right ventricular cardiomyopathy, and desmosomal proteins are targeted by pathogenic autoantibodies in skin blistering diseases such as pemphigus. Here, we review a set of newly discovered pathogenic alterations and discuss the structural repercussions of debilitating mutations on desmosomal proteins. The architectures of native desmosomal assemblies have been visualized by cryo-electron microscopy and cryo-electron tomography, and the network of protein domain interactions is becoming apparent. Plakophilin and desmoplakin mutations have been discovered to alter binding interfaces, structures, and stabilities of folded domains that have been resolved by X-ray crystallography and NMR spectroscopy. The flexibility within desmoplakin has been revealed by small-angle X-ray scattering and fluorescence assays, explaining how mechanical stresses are accommodated. These studies have shown that the structural and functional consequences of desmosomal mutations can now begin to be understood at multiple levels of spatial and temporal resolution. This review discusses the recent structural insights and raises the possibility of using modeling for mechanism-based diagnosis of how deleterious mutations alter the integrity of solid tissues., (© 2013. Published by Elsevier Ltd. All rights reserved.)

Background: Arrhythmogenic cardiomyopathy (AC) is considered a predominantly right ventricular (RV) desmosomal disease. However, left-dominant forms due to desmosomal gene mutations, including PKP2 variant c.419C>T, have been described. Recently, a nondesmosomal phospholamban (PLN) mutation (c.40&#95;42delAGA) has been identified, causing dilated cardiomyopathy and arrhythmias., Objective: To gain more insight into pathogenicity of the PKP2 variant c.419C>T by cosegregation analysis of the PKP2 variant c.419C>T vs the PLN mutation c.40&#95;42delAGA., Methods: A Dutch family (13 family members, median age 49 years, range 34-71 years) with ventricular tachycardia underwent (1) meticulous phenotypic characterization and (2) screening of 5 desmosomal genes (PKP2, DSC2, DSG2, DSP, JUP) and PLN., Results: Six family members fulfilled 2010 AC Task Force Criteria. Seven had signs of left ventricular (LV) involvement (inverted T waves in leads V4-V6, LV wall motion abnormalities and late enhancement, and reduced LV ejection fraction), including 6 family members with proven AC. The PKP2 variant c.419C>T was found as a single variant in 3 family members, combined with the PLN mutation c.40&#95;42delAGA in 3 others. PLN mutation was found in 9 family members, including the 6 with AC and all 7 with LV involvement. The PLN mutation c.40&#95;42delAGA was found as a single mutation in 6, combined with the PKP2 variant c.419C>T in 3 others. A low-voltage electrocardiogram was seen in 4 of 9 PLN mutation-positive subjects. None of the family members with the single PKP2 variant showed any sign of RV or LV involvement., Conclusions: The PLN mutation c.40&#95;42delAGA cosegregates with AC and with electrocardiographic and structural LV abnormalities. In this family, there was no evidence of disease-causing contribution of the PKP2 variant c.419C>T., (Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Humans sleep approximately a third of their lifetime. The observation that individuals with either long or short sleep duration show associations with metabolic syndrome and psychiatric disorders suggests that the length of sleep is adaptive. Although sleep duration can be influenced by photoperiod (season) and phase of entrainment (chronotype), human familial sleep disorders indicate that there is a strong genetic modulation of sleep. Therefore, we conducted high-density genome-wide association studies for sleep duration in seven European populations (N=4251). We identified an intronic variant (rs11046205; P=3.99 × 10(-8)) in the ABCC9 gene that explains ≈5% of the variation in sleep duration. An influence of season and chronotype on sleep duration was solely observed in the replication sample (N=5949). Meta-analysis of the associations found in a subgroup of the replication sample, chosen for season of entry and chronotype, together with the discovery results showed genome-wide significance. RNA interference knockdown experiments of the conserved ABCC9 homologue in Drosophila neurons renders flies sleepless during the first 3 h of the night. ABCC9 encodes an ATP-sensitive potassium channel subunit (SUR2), serving as a sensor of intracellular energy metabolism.

Aims: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by fibrofatty replacement of muscular fibers predominantly in the right ventricle and with ventricular arrhythmias as the main clinical manifestation. Mutations in several components of the desmosome genes have been identified and mutations of the plakophilin-2 (PKP-2) gene are a common cause of ARVC. The aim of this study is to investigate the correlation between genotype and phenotype in a family with a novel PKP-2 variant., Methods and Results: This study describes the clinical findings and genetic analysis in a family with ARVC. A part of the family has been followed clinically long term for up to 27 years. Two not previously reported PKP-2 variants (L506P and T526A) have been identified in this family. Even though all members of this family share the novel variant L506P, the clinical features, i.e., their phenotypes are different. The L506P variant is located in exon 7 and affects a highly conserved residue. The same amino acid, leucine, is present in all species evaluated, indicating a functional importance and the variant is predicted to be damaging. The novel L506P variant in the PKP-2 gene is thus a possible pathogenic alteration in the described family with ARVC. In contrast, the T526A variant is weakly conserved and predicted to be tolerated., Conclusion: While many of the reported ARVC mutations are truncating mutations, the possibly damaging variant found in this family, is a missense alteration affecting a highly conserved residue 506 located in exon 7.

Background: Tuberculosis has been associated with genetic variation in host immunity. We hypothesized that single-nucleotide polymorphisms (SNPs) in SIGIRR, a negative regulator of Toll-like receptor/IL-1R signaling, are associated with susceptibility to tuberculosis., Methods: We used a case-population study design in Vietnam with cases that had either tuberculous meningitis or pulmonary tuberculosis. We genotyped 6 SNPs in the SIGIRR gene region (including the adjacent genes PKP3 and TMEM16J) in a discovery cohort of 352 patients with tuberculosis and 382 controls. Significant associations were genotyped in a validation cohort (339 patients with tuberculosis, 376 controls)., Results: Three SNPs (rs10902158, rs7105848, rs7111432) were associated with tuberculosis in discovery and validation cohorts. The polymorphisms were associated with both tuberculous meningitis and pulmonary tuberculosis and were strongest with a recessive genetic model (odds ratios, 1.5-1.6; P = .0006-.001). Coinheritance of these polymorphisms with previously identified risk alleles in Toll-like receptor 2 and TIRAP was associated with an additive risk of tuberculosis susceptibility., Conclusions: These results demonstrate a strong association of SNPs in the PKP3-SIGIRR-TMEM16J gene region and tuberculosis in discovery and validation cohorts. To our knowledge, these are the first associations of polymorphisms in this region with any disease.

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a progressive myocardial disorder caused by mutations of desmosomal cell adhesion proteins. The prevalence of these variants in the general population is unknown., Objective: This study examined the spectrum and population prevalence of desmosomal mutations predisposing to ARVC in Finland., Methods: We screened 29 Finnish ARVC probands for mutations in the DSP, DSG2, and DSC2 genes. All Finnish-type ARVC-associated mutations, including those 3 previously identified in PKP2 in the same patient group, were analyzed in the population-based Health 2000 cohort of 6,334 individuals and tested for association with electrocardiographic variables., Results: We detected 2 novel mutations: DSG2 3059&#95;3062delAGAG and DSP T1373A. DSG2 3059&#95;3062delAGAG was present in a family with 5 mutation carriers. The endomyocardial samples of the DSG2 deletion carrier showed reduced immunoreactive signal for desmoglein-2, plakophilin-2, plakoglobin, and desmoplakin. DSP T1373A was found in 1 proband with typical right ventricular disease and exercise-related ventricular tachycardia. In the population sample, the collective prevalence of all 5 mutations identified in the 29 ARVC patients (PKP2 Q62K, Q59L, N613K, DSG2 3059&#95;3062delAGAG, and DSP T1373A) was 31 of 6,334 individuals, or 0.5%. The apparent founder mutation PKP2 Q59L is present in 0.3% of Finns and was previously shown to have an approximately 20% disease penetrance., Conclusion: One of 200 Finns carries a desmosomal mutation that may predispose to ARVC and its clinical sequelae. ARVC-associated mutations may thus be more prevalent in the population than expected based on the published ARVC prevalence data., (Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a lethal condition characterised by ventricular tachyarrhythmias, right and/or left ventricular involvement and fibrofatty infiltrations in the myocardium. The disease has been associated with mutations in genes encoding desmosomal proteins., Objective: To thoroughly evaluate an ARVC cohort for desmosomal mutations and large genomic rearrangements and characterise the phenotype associated with double-mutation carrier status., Methods: 65 unrelated patients (55 fulfilling current criteria and 10 borderline cases) were screened for mutations in all known desmosome genes (desmocollin-2 (DSC2), desmoglein-2 (DSG2), desmoplakin (DSP), plakoglobin (JUP) and plakophilin-2 (PKP2)) and TGFb3. Presence of genomic rearrangements was assessed by multiplex ligation-dependent probe amplification. Results The screening identified 19 different mutations: two mutations in DSG2, four in DSC2, two in DSP (one heterozygous and one homozygous), four in JUP (one patient with compound heterozygous) and seven in PKP2. No genomic rearrangements or mutations in TGFb3 were identified. Ten of the mutations were novel. Seven families carried more than one mutation. Clinical evaluation of these families showed a variable phenotype associated with the double-mutation carrier status. The homozygous desmoplakin mutation (DSP p.G2056R+p.G2056R) carrier came from a consanguineous Danish family and had left ventricular involvement, palmar keratoderma and curly hair consistent with a Carvajal-like syndrome., Conclusions: 33% of patients in this Danish cohort with ARVC carried desmosomal mutations with a surprisingly wide mutation spectrum. A substantial proportion of patients carried more than one mutation. Our study supports comprehensive desmosomal mutation screening beyond the first encountered mutation, whereas routine screening for genomic rearrangements does not seem indicated.