New population-based exome data are questioning the pathogenicity of previously cardiomyopathy-associated genetic variants

Cardiomyopathies are a heterogeneous group of diseases with various etiologies. We focused on three genetically determined cardiomyopathies: hypertrophic (HCM), dilated (DCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC). Eighty-four genes have so far been associated with these cardiomyopathies, but the disease-causing effect of reported variants is often dubious. In order to identify possible false-positive variants, we investigated the prevalence of previously reported cardiomyopathy-associated variants in recently published exome data. We searched for reported missense and nonsense variants in the NHLBI-Go Exome Sequencing Project (ESP) containing exome data from 6500 individuals. In ESP, we identified 94 variants out of 687 (14%) variants previously associated with HCM, 58 out of 337 (17%) variants associated with DCM, and 38 variants out of 209 (18%) associated with ARVC. These findings correspond to a genotype prevalence of 1:4 for HCM, 1:6 for DCM, and 1:5 for ARVC. PolyPhen-2 predictions were conducted on all previously published cardiomyopathy-associated missense variants. We found significant overrepresentation of variants predicted as being benign among those present in ESP compared with the ones not present. In order to validate our findings, seven variants associated with cardiomyopathy were genotyped in a control population and this revealed frequencies comparable with the ones found in ESP. In conclusion, we identified genotype prevalences up to more than one thousand times higher than expected from the phenotype prevalences in the general population (HCM 1:500, DCM 1:2500, and ARVC 1:5000) and our data suggest that a high number of these variants are not monogenic causes of cardiomyopathy.     

The role of cognitive biases and personality variables in subclinical delusional ideation

Introduction. A number of cognitive biases, most notably a data gathering bias characterised by “jumping to conclusions” (JTC), and the “bias against disconfirmatory evidence” (BADE), have been shown to be associated with delusions and subclinical delusional ideation. Certain personality variables, particularly “openness to experience”, are thought to be associated with schizotypy.

Methods. Using structural equation modelling, we examined the association between two higher order subfactors (“aspects”) of “openness to experience” (labelled “openness” and “intellect”), these cognitive biases, and their relationship to subclinical delusional ideation in 121 healthy, nonpsychiatric controls.

Results. Our results suggest that cognitive biases (specifically the data gathering bias and BADE) and the “openness” aspect are independently associated with subclinical delusional ideation, and the data gathering bias is weakly associated with “positive schizotypy”. “Intellect” is negatively associated with delusional ideation and might play a potential protective role.

Conclusions. Cognitive biases and personality are likely to be independent risk factors for the development of delusions.     

Evidence for a Direct Effect of the NAD+ Precursor Acipimox on Muscle Mitochondrial Function in Humans

Recent preclinical studies showed the potential of nicotinamide adenine dinucleotide (NAD⁺) precursors to increase oxidative phosphorylation and improve metabolic health, but human data are lacking. We hypothesize that the nicotinic acid derivative acipimox, an NAD⁺ precursor, would directly affect mitochondrial function independent of reductions in nonesterified fatty acid (NEFA) concentrations. In a multicenter randomized crossover trial, 21 patients with type 2 diabetes (age 57.7 ± 1.1 years, BMI 33.4 ± 0.8 kg/m²) received either placebo or acipimox 250 mg three times daily dosage for 2 weeks. Acipimox treatment increased plasma NEFA levels (759 ± 44 vs. 1,135 ± 97 μmol/L for placebo vs. acipimox, P < 0.01) owing to a previously described rebound effect. As a result, skeletal muscle lipid content increased and insulin sensitivity decreased. Despite the elevated plasma NEFA levels, ex vivo mitochondrial respiration in skeletal muscle increased. Subsequently, we showed that acipimox treatment resulted in a robust elevation in expression of nuclear-encoded mitochondrial gene sets and a mitonuclear protein imbalance, which may indicate activation of the mitochondrial unfolded protein response. Further studies in C2C12 myotubes confirmed a direct effect of acipimox on NAD⁺ levels, mitonuclear protein imbalance, and mitochondrial oxidative capacity. To the best of our knowledge, this study is the first to demonstrate that NAD⁺ boosters can also directly affect skeletal muscle mitochondrial function in humans.