Reactivation of the Epicardium at the Origin of Myocardial Fibro-Fatty Infiltration During the Atrial Cardiomyopathy.

RATIONALE: Fibro-fatty infiltration of subepicardial layers of the atrial wall has been shown to contribute to the substrate of atrial fibrillation. OBJECTIVE: Here, we examined if the epicardium that contains multipotent cells is involved in this remodeling process. METHODS AND RESULTS: One hundred nine human surgical right atrial specimens were evaluated. There was a relatively greater extent of epicardial thickening and dense fibro-fatty infiltrates in atrial tissue sections from patients aged over 70 years who had mitral valve disease or atrial fibrillation when compared with patients aged less than 70 years with ischemic cardiomyopathy as indicated using logistic regression adjusted for age and gender. Cells coexpressing markers of epicardial progenitors and fibroblasts were detected in fibro-fatty infiltrates. Such epicardial remodeling was reproduced in an experimental model of atrial cardiomyopathy in rat and in Wilms tumor 1 (WT1)CreERT2/+;ROSA-tdT+/- mice. In the latter, genetic lineage tracing demonstrated the epicardial origin of fibroblasts within fibro-fatty infiltrates. A subpopulation of human adult epicardial-derived cells expressing PDGFR (platelet-derived growth factor receptor)-α were isolated and differentiated into myofibroblasts in the presence of Ang II (angiotensin II). Furthermore, single-cell RNA-sequencing analysis identified several clusters of adult epicardial-derived cells and revealed their specification from adipogenic to fibrogenic cells in the rat model of atrial cardiomyopathy. CONCLUSIONS: Epicardium is reactivated during the formation of the atrial cardiomyopathy. Subsets of adult epicardial-derived cells, preprogrammed towards a specific cell fate, contribute to fibro-fatty infiltration of subepicardium of diseased atria. Our study reveals the biological basis for chronic atrial myocardial remodeling that paves the way of atrial fibrillation.

A large-scale exome array analysis of venous thromboembolism.

Although recent Genome-Wide Association Studies have identified novel associations for common variants, there has been no comprehensive exome-wide search for low-frequency variants that affect the risk of venous thromboembolism (VTE). We conducted a meta-analysis of 11 studies comprising 8,332 cases and 16,087 controls of European ancestry and 382 cases and 1,476 controls of African American ancestry genotyped with the Illumina HumanExome BeadChip. We used the seqMeta package in R to conduct single variant and gene-based rare variant tests. In the single variant analysis, we limited our analysis to the 64,794 variants with at least 40 minor alleles across studies (minor allele frequency [MAF] ~0.08%). We confirmed associations with previously identified VTE loci, including ABO, F5, F11, and FGA. After adjusting for multiple testing, we observed no novel significant findings in single variant or gene-based analysis. Given our sample size, we had greater than 80% power to detect minimum odds ratios greater than 1.5 and 1.8 for a single variant with MAF of 0.01 and 0.005, respectively. Larger studies and sequence data may be needed to identify novel low-frequency and rare variants associated with VTE risk.

A genome-wide association study identifies two loci associated with heart failure due to dilated cardiomyopathy.

AIMS: Dilated cardiomyopathy (DCM) is a major cause of heart failure with a high familial recurrence risk. So far, the genetics of DCM remains largely unresolved. We conducted the first genome-wide association study (GWAS) to identify loci contributing to sporadic DCM. METHODS AND RESULTS: One thousand one hundred and seventy-nine DCM patients and 1108 controls contributed to the discovery phase. Pools of DNA stratified on disease status, population, age, and gender were constituted and used for testing association of DCM with 517 382 single nucleotide polymorphisms (SNPs). Three DCM-associated SNPs were confirmed by individual genotyping (P < 5.0 10(-7)), and two of them, rs10927875 and rs2234962, were replicated in independent samples (1165 DCM patients and 1302 controls), with P-values of 0.002 and 0.009, respectively. rs10927875 maps to a region on chromosome 1p36.13 which encompasses several genes among which HSPB7 has been formerly suggested to be implicated in DCM. The second identified locus involves rs2234962, a non-synonymous SNP (c.T757C, p. C151R) located within the sequence of BAG3 on chromosome 10q26. To assess whether coding mutations of BAG3 might cause monogenic forms of the disease, we sequenced BAG3 exons in 168 independent index cases diagnosed with familial DCM and identified four truncating and two missense mutations. Each mutation was heterozygous, present in all genotyped relatives affected by the disease and absent in a control group of 347 healthy individuals, strongly suggesting that these mutations are causing the disease. CONCLUSION: This GWAS identified two loci involved in sporadic DCM, one of them probably implicates BAG3. Our results show that rare mutations in BAG3 contribute to monogenic forms of the disease, while common variant(s) in the same gene are implicated in sporadic DCM.

The factor XII -4C>T variant and risk of common thrombotic disorders: A HuGE review and meta-analysis of evidence from observational studies.

Coagulation factor XII is involved in thrombus formation and therefore may play a role in the etiology of thrombotic disorders. A common variant in the factor XII (F12) gene (-4C>T, rs1801020) results in decreased plasma levels of this coagulation factor. The existence of associations between low factor XII levels or F12 variants and thrombotic outcomes has been debated for more than a decade. The authors conducted a review and meta-analysis to evaluate the evidence for an association between F12 -4C>T and 2 common thrombotic outcomes: venous thromboembolism and myocardial infarction, which are hypothesized to share some etiologic pathways. MEDLINE, EMBASE, and HuGE Navigator were searched through July 2009 to identify relevant epidemiologic studies, and data were summarized using random-effects meta-analysis. Sixteen candidate gene studies (4,386 cases, 40,089 controls) were analyzed. None of the investigated contrasts reached statistical significance at P < 0.05, apart from a very weak association with myocardial infarction for the TT + CT versus CC contrast (odds ratio = 1.13, 95% confidence interval: 1.00, 1.27). Overall, based on the synthesis of observational studies, the evidence for an association between F12 -4C>T and venous thromboembolism and myocardial infarction is weak.

Effect of cytochrome P450 2C19 genotype on voriconazole exposure in cystic fibrosis lung transplant patients.

PURPOSE: Voriconazole is widely used to treat invasive aspergillosis after lung transplantation. In cystic fibrosis patients, the interindividual variability in drug disposition complicates the optimal voriconazole dosing and increases the risk of toxicity. The objective of this retrospective study was to evaluate the influence of CYP2C19 genotype on voriconazole response in lung transplant patients with cystic fibrosis. METHODS: We retrospectively studied 24 Caucasian cystic fibrosis lung transplant recipients who received voriconazole. We analyzed the influence of CYP2C19 genotype (*2 and *17 alleles) on voriconazole exposure and maintenance dose and side effects. RESULTS: Heterozygous carriers of the CYP2C19*2-deficient allele required lower maintenance doses (440 ± 107 mg/day) compared with wild-type and CYP2C19*17-allele carriers (633 ± 197 mg/day and 600 ± 193 mg/day, respectively, P<0.05). The time to achieve the therapeutic range and the proportion of out-of-range concentrations were significantly higher in the CYP2C19*2 group (31.3% vs. 12.1% and 9.8% of above-range levels in the CYP2C19*1 and CYP2C19*17 groups, respectively) or CYP2C19*17 group (37.9% vs. 15.6% and 13% of below-range levels in the CYP2C19*1 and CYP2C19*2 groups, respectively) (P<0.01). No relationship was found between voriconazole toxicity and CYP2C19 status. CONCLUSIONS: In this frail population, voriconazole exposure is strongly influenced by CYP2C19 genotype, and determining the genotype before voriconazole initiation may help determine the initial dosing regimen that will promptly achieve therapeutic plasma levels without producing out-of-range levels.

Common Risk Factors Add to Inherited Thrombophilia to Predict Venous Thromboembolism Risk in Families.

The clinical venous thromboembolism (VTE) pattern often shows wide heterogeneity within relatives of a VTE-affected family, although they carry the same thrombophilia defect. It is then mandatory to develop additional tools for assessing VTE risk in families with thrombophilia. This study aims to assess whether common environmental and genetic risk factors for VTE contribute to explain this heterogeneity. A total of 2,214 relatives from 651 families with known inherited thrombophilia were recruited at the referral center for thrombophilia in Marseilles, France, from 1986 to 2013. A thrombophilia screening was systematically performed in all included relatives. According to the severity of the thrombophilia defect, individuals were split into three groups: no familial defect, mild thrombophilia, and severe thrombophilia. In addition, common genetic factors (ABO blood group and 11 polymorphisms selected on the basis of their association with VTE in the general population) were genotyped. Furthermore, body mass index and smoking were collected. VTE incidence was 1.74, 3.64, and 6.40 per 1,000 person-years in individuals with no familial defect, mild thrombophilia, and severe thrombophilia, respectively. Five common risk factors were associated with VTE in this population: obesity, smoking, ABO blood group, and F11 _rs2036914 and FGG _rs2066865 polymorphisms. These common factors were then included into a three-level risk score. The score was highly efficient for assessing VTE risk in mild thrombophilia patients by identifying two groups with different VTE risk; individuals with low score had the same risk as individuals with no familial defect whereas individuals with high score had the same risk as individuals with severe thrombophilia. An overall score including the five items plus the thrombophilia status was built and displayed an area under the receiver operating characteristic curve of 0.702 for discriminating VTE and non-VTE relatives. In conclusion, integrating common environmental and genetic risk factors improved VTE risk assessment in relatives from families with thrombophilia.

Genetic variations at the endocannabinoid type 1 receptor gene (CNR1) are associated with obesity phenotypes in men.

CONTEXT: The endocannabinoid system modulates food intake and body weight in animal models. Treatment with the cannabinoid type 1 receptor blocker, rimonabant, reduces body weight in obese individuals. OBJECTIVE: The aim of this study was to determine whether single nucleotide polymorphisms of the gene encoding cannabinoid type 1 receptor, CNR1, are associated with body fat mass and distribution in two independent samples of white European adult men. DESIGN, SETTING, AND PARTICIPANTS: The 3813A/G and 4895A/G single nucleotide polymorphisms at the exon 4 of CNR1 were genotyped in 930 participants to the Olivetti Prospective Heart Study (OPHS) in Southern Italy and in 216 participants to the Wandsworth Heart and Stroke Study in the United Kingdom. Retrospective analysis was also performed on an OPHS subsample (n = 360) for which anthropometric data from 1987 and 1994-1995 examinations were available. MAIN OUTCOME MEASURES: CNR1 genotypes and anthropometric measures of body fat distribution were determined. RESULTS: In the OPHS study, the 3813G allele was associated with increased subscapular skinfold thickness (24.2 +/- 9.1 vs. 22.8 +/- 7.7 mm; P = 0.031) and waist circumference (WC) (99.1 +/- 8.8 vs. 97.7 +/- 8.8 cm; P = 0.050). No association was observed with 4895A/G variant. Haplotype analysis confirmed that the unique haplotype carrying the 3813G was associated with increased WC and subscapular skinfold thickness. Similar results were observed in the OPHS retrospective subsample and the Wandsworth Heart and Stroke Study sample. In the latter, the 3813G was associated with increased WC (96.8 +/- 11.3 vs. 91.6 +/- 10.4 cm; P = 0.006). CONCLUSIONS: Genetic variants at CNR1 are associated with obesity-related phenotypes in men. The detection of polymorphic variants in genes involved in the process of fat accumulation may help identify specific targets for pharmacological treatment of obesity and related metabolic abnormalities.

Associations of PPARGC1A haplotypes with plaque score but not with intima-media thickness of carotid arteries in middle-aged subjects.

BACKGROUND AND PURPOSE: Peroxisome proliferator activated receptor gamma coactivator 1alpha (PGC-1alpha, PPARGC1A) integrates the transcriptional program of mitochondrial biogenesis. Mitochondria are the main source of cellular reactive oxygen species implicated in atherogenesis. We therefore ascertained associations of PPARGC1A polymorphisms with asymptomatic carotid atherosclerosis. METHODS: Eight single nucleotide polymorphisms tagging two haplotype blocks within PPARGC1A were studied in 1379 participants of the Salzburg Atherosclerosis Prevention Program in Subjects at High Individual Risk. Early atherosclerosis was assessed by intima-media thickness and extent of plaques (B-score) of the carotid arteries. RESULTS: No associations of carotid artery intima-media thickness measurements with block 1 or 2 haplotype distributions or individual haplotypes were observed. However, the block 1 haplotype carrying the variant C nucleotide at -3974 relative to the transcription start site was associated with disease status defined by the presence of more than one minimal lesion and the -3974 C allele was associated with decreased risk (odds ratio=0.60, P=0.007) after adjustment for linkage disequilibrium between single nucleotide polymorphisms. CONCLUSIONS: These result are consistent with the concept that risk factors for distinct carotid phenotypes may vary and suggest, but do not prove, that PGC-1alpha may contribute to the regulation of atherogenic pathways.

Combined effects of genetic and environmental factors on insulin resistance associated with reduced fetal growth.

It has been suggested that the insulin resistance (IR) associated with reduced fetal growth results from interactions between genetic factors and an unfavorable fetal environment. In addition, the adipose tissue seems to play a key role in this association. We investigated whether polymorphisms in tumor necrosis factor (TNF)-alpha(G-308A), beta3 adrenoreceptor (ADRB3)(G+250C), and peroxisome proliferator-activated receptor (PPAR)-gamma2(Pro12Ala), key molecules of the adipose tissue, might affect the IR associated with reduced fetal growth. They were genotyped in 171 subjects who were born small for gestational age (SGA) and in 233 subjects who were born appropriate for gestational age (AGA) and underwent an oral glucose tolerance test (OGTT). The SGA group showed higher serum insulin concentrations than the AGA group at fasting (P = 0.03) and after stimulation (P = 0.0007), whereas no difference in serum glucose concentrations was observed. The frequencies of the alleles of these three polymorphisms were similar in both groups. In neither group did the polymorphisms affect glucose tolerance. In the SGA group, fasting insulin-to-glucose ratios were significantly higher in the TNF/-308A (P = 0.03), the PPAR/Ala12 (P = 0.01), and the ADRB3/+250G (P = 0.02) carriers than in the noncarriers. Results were comparable for fasting insulin concentration and insulin excursion under OGTT. No such amplification was observed in the AGA group. The effects of the PPAR/ProAla12 (P = 0.005) and the ADRB3/G+250G (P = 0.009) gene polymorphisms on IR indexes were significantly potentiated by BMI in the SGA group. In conclusion, our data exemplify the interaction between intrauterine environmental and genetic factors in the development of the IR associated with reduced fetal growth. They also point to the key role of adipose tissue in this association.

Genome-wide association analysis identifies a susceptibility locus for pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a rare, severe disease resulting from progressive obliteration of small-caliber pulmonary arteries by proliferating vascular cells. PAH can occur without recognized etiology (idiopathic PAH), be associated with a systemic disease or occur as a heritable form, with BMPR2 mutated in approximately 80% of familial and 15% of idiopathic PAH cases. We conducted a genome-wide association study (GWAS) based on 2 independent case-control studies for idiopathic and familial PAH (without BMPR2 mutations), including a total of 625 cases and 1,525 healthy individuals. We detected a significant association at the CBLN2 locus mapping to 18q22.3, with the risk allele conferring an odds ratio for PAH of 1.97 (1.59-2.45; P = 7.47 × 10(-10)). CBLN2 is expressed in the lung, and its expression is higher in explanted lungs from individuals with PAH and in endothelial cells cultured from explanted PAH lungs.

Association between angiotensin-converting enzyme gene polymorphisms and diabetic nephropathy: case-control, haplotype, and family-based study in three European populations.

Angiotensin 1-converting enzyme gene (ACE) is a risk factor for diabetic nephropathy (DN) in patients with type 1 diabetes. The selection of this candidate gene is supported by cross-sectional and follow-up studies, but no convincing family-based studies are available. Recruited were 1057 patients (with DN: persistent albuminuria with or without renal failure) and 1127 control subjects (long-standing [> or =15 yr] normoalbuminuric patients with type 1 diabetes) in Denmark, Finland, and France and 532 family trios that were composed of 244 trios with DN probands and 288 trios with non-DN probands. Five ACE polymorphisms were studied. In the case-control analysis, the rs1800764-C, rs4311-T, Insertion/deletion (I/D or rs1799752)-D, rs4366-G, and rs12449782-G alleles were associated with an increased risk for DN, homogeneously across populations, with allelic odds ratios of 1.11 (95% confidence interval 1.00 to 1.22), 1.18 (1.04 to 1.33), 1.13 (1.02 to 1.23), 1.10 (0.99 to 1.20), and 1.12 (1.01 to 1.23), respectively. Haplotype analysis further demonstrated that the haplotype defined by the D, rs4366_G and rs12449782_G alleles was associated with a greater risk for DN. Even though no significant allelic overtransmission to DN or non-DN probands was detected, the family-based study provided consistent results with the case-control analysis. In a large case-control study, it was shown that the ACE polymorphisms were associated with DN; these findings were not confirmed in a family-based association study. This study population is suitable to search for additional candidate genes for DN.

Gender-specific association of a perilipin gene haplotype with obesity risk in a white population.

OBJECTIVE: Perilipin is a class of protein-coating lipid droplets in adipocytes and steroidogenic cells. Our purpose was to examine the association between common single-nucleotide polymorphisms (SNPs) at the perilipin (PLIN) locus and obesity, as well as related phenotypes, in unrelated American adults. RESEARCH METHODS AND PROCEDURES: Four PLIN SNPs (PLIN 6209T>C, 11482G>A, 13041A>G, and 14995A>T) were typed in 734 white subjects (373 men and 361 women) attending a residential lifestyle intervention program. The baseline anthropometric and biochemical measures were used. Obesity was defined as BMI > or = 30 kg/m(2). RESULTS: Multivariate analysis demonstrated that, in women, two of the SNPs (13041A>G, and 14995A>T) were significantly associated with percentage body fat (p = 0.016 for 13041A>G and p = 0.010 for 14995A>T) and waist circumference (p = 0.020 for 13041A>G and p = 0.045 for 14995A>T). Moreover, haplotype analysis using these two SNPs indicated that haplotypes A/T and G/T were both associated with significantly increased obesity risk (odds ratio = 1.76, 95% confidence interval 1.07 to 2.90 for haplotype A/T, and odds ratio = 1.73, 95% confidence interval 1.06 to 2.82 for haplotype G/T) when compared with haplotype A/A. No significant associations between PLIN variations and obesity were found in men. DISCUSSION: Our data support the hypothesis that the PLIN locus may be a significant genetic determinant for obesity risk in whites and that women are more sensitive to the genetic effects of perilipin than men.