Mitochondria are implicated in the pathogenesis of cardiovascular diseases (CVDs) but the reasons for this are not well understood. Maternally-inherited population variants of mitochondrial DNA ...(mtDNA) which affect all mtDNA molecules (homoplasmic) are associated with cardiometabolic traits and the risk of developing cardiovascular disease. However, it is not known whether mtDNA mutations only affecting a proportion of mtDNA molecules (heteroplasmic) also play a role. To address this question, we performed a high-depth (~1000-fold) mtDNA sequencing of blood DNA in 1,399 individuals with hypertension (HTN), 1,946 with ischemic heart disease (IHD), 2,146 with ischemic stroke (IS), and 723 healthy controls. We show that the per individual burden of heteroplasmic single nucleotide variants (mtSNVs) increases with age. The age-effect was stronger for low-level heteroplasmies (heteroplasmic fraction, HF, 5-10%), likely reflecting acquired somatic events based on trinucleotide mutational signatures. After correcting for age and other confounders, intermediate heteroplasmies (HF 10-95%) were more common in hypertension, particularly involving non-synonymous variants altering the amino acid sequence of essential respiratory chain proteins. These findings raise the possibility that heteroplasmic mtSNVs play a role in the pathophysiology of hypertension.
Myocardial infarction, a leading cause of death in the Western world, usually occurs when the fibrous cap overlying an atherosclerotic plaque in a coronary artery ruptures. The resulting exposure of ...blood to the atherosclerotic material then triggers thrombus formation, which occludes the artery. The importance of genetic predisposition to coronary artery disease and myocardial infarction is best documented by the predictive value of a positive family history. Next-generation sequencing in families with several affected individuals has revolutionized mutation identification. Here we report the segregation of two private, heterozygous mutations in two functionally related genes, GUCY1A3 (p.Leu163Phefs*24) and CCT7 (p.Ser525Leu), in an extended myocardial infarction family. GUCY1A3 encodes the α1 subunit of soluble guanylyl cyclase (α1-sGC), and CCT7 encodes CCTη, a member of the tailless complex polypeptide 1 ring complex, which, among other functions, stabilizes soluble guanylyl cyclase. After stimulation with nitric oxide, soluble guanylyl cyclase generates cGMP, which induces vasodilation and inhibits platelet activation. We demonstrate in vitro that mutations in both GUCY1A3 and CCT7 severely reduce α1-sGC as well as β1-sGC protein content, and impair soluble guanylyl cyclase activity. Moreover, platelets from digenic mutation carriers contained less soluble guanylyl cyclase protein and consequently displayed reduced nitric-oxide-induced cGMP formation. Mice deficient in α1-sGC protein displayed accelerated thrombus formation in the microcirculation after local trauma. Starting with a severely affected family, we have identified a link between impaired soluble-guanylyl-cyclase-dependent nitric oxide signalling and myocardial infarction risk, possibly through accelerated thrombus formation. Reversing this defect may provide a new therapeutic target for reducing the risk of myocardial infarction.
Abstract Background and Aims A cardiovascular disease polygenic risk score (CVD-PRS) can stratify individuals into different categories of cardiovascular risk, but whether the addition of a CVD-PRS ...to clinical risk scores improves the identification of individuals at increased risk in a real-world clinical setting is unknown. Methods The Genetics and the Vascular Health Check Study (GENVASC) was embedded within the UK National Health Service Health Check (NHSHC) programme which invites individuals between 40–74 years of age without known CVD to attend an assessment in a UK general practice where CVD risk factors are measured and a CVD risk score (QRISK2) is calculated. Between 2012–2020, 44,141 individuals (55.7% females, 15.8% non-white) who attended an NHSHC in 147 participating practices across two counties in England were recruited and followed. When 195 individuals (cases) had suffered a major CVD event (CVD death, myocardial infarction or acute coronary syndrome, coronary revascularisation, stroke), 396 propensity-matched controls with a similar risk profile were identified, and a nested case-control genetic study undertaken to see if the addition of a CVD-PRS to QRISK2 in the form of an integrated risk tool (IRT) combined with QRISK2 would have identified more individuals at the time of their NHSHC as at high risk (QRISK2 10-year CVD risk of ≥10%), compared with QRISK2 alone. Results The distribution of the standardised CVD-PRS was significantly different in cases compared with controls (cases mean score .32; controls, −.18, P = 8.28×10−9). QRISK2 identified 61.5% (95% confidence interval CI: 54.3%–68.4%) of individuals who subsequently developed a major CVD event as being at high risk at their NHSHC, while the combination of QRISK2 and IRT identified 68.7% (95% CI: 61.7%–75.2%), a relative increase of 11.7% (P = 1×10−4). The odds ratio (OR) of being up-classified was 2.41 (95% CI: 1.03–5.64, P = .031) for cases compared with controls. In individuals aged 40–54 years, QRISK2 identified 26.0% (95% CI: 16.5%–37.6%) of those who developed a major CVD event, while the combination of QRISK2 and IRT identified 38.4% (95% CI: 27.2%–50.5%), indicating a stronger relative increase of 47.7% in the younger age group (P = .001). The combination of QRISK2 and IRT increased the proportion of additional cases identified similarly in women as in men, and in non-white ethnicities compared with white ethnicity. The findings were similar when the CVD-PRS was added to the atherosclerotic cardiovascular disease pooled cohort equations (ASCVD-PCE) or SCORE2 clinical scores. Conclusions In a clinical setting, the addition of genetic information to clinical risk assessment significantly improved the identification of individuals who went on to have a major CVD event as being at high risk, especially among younger individuals. The findings provide important real-world evidence of the potential value of implementing a CVD-PRS into health systems.
Genome-wide association studies have linked variants at chromosome 10q23 with increased coronary artery disease risk. The disease-associated variants fall in
, which encodes lysosomal acid lipase ...(LAL), the enzyme responsible for lysosomal cholesteryl ester hydrolysis. Loss-of-function mutations in
result in accelerated atherosclerosis. Surprisingly, the coronary artery disease variants are associated with increased
expression in some cell types. In this study, we address this apparent contradiction.
We investigated a coding variant rs1051338, which is in high linkage disequilibrium (
=0.89) with the genome-wide association study lead-associated variant rs2246833 and causes a nonsynonymous threonine to proline change within the signal peptide of LAL. Transfection of allele-specific expression constructs showed that the risk allele results in reduced lysosomal LAL protein (
=0.004) and activity (
=0.005). Investigation of LAL localization and turnover showed the risk LAL protein is degraded more quickly. This mechanism was confirmed in disease-relevant macrophages from individuals homozygous for either the nonrisk or risk allele. There was no difference in LAL protein or activity in whole macrophage extracts; however, we found reduced LAL protein (
=0.02) and activity (
=0.026) with the risk genotype in lysosomal extracts, suggesting that the risk genotype affects lysosomal LAL activity. Inhibition of the proteasome resulted in equal amounts of lysosomal LAL protein in risk and nonrisk macrophages.
Our findings show that the coronary artery disease-associated coding variant rs1051338 causes reduced lysosomal LAL protein and activity because of increased LAL degradation, providing a plausible causal mechanism of increased coronary artery disease risk.
We conducted genome-wide association analyses of mean leukocyte telomere length in 2,917 individuals, with follow-up replication in 9,492 individuals. We identified an association with telomere ...length on 3q26 (rs12696304, combined P = 3.72 × 10−14) at a locus that includes TERC, which encodes the telomerase RNA component. Each copy of the minor allele of rs12696304 was associated with an ∼75-base-pair reduction in mean telomere length, equivalent to ∼3.6 years of age-related telomere-length attrition.
Runs of homozygosity (ROHs) are recognized signature of recessive inheritance. Contributions of ROHs to the genetic architecture of coronary artery disease and regulation of gene expression in cells ...relevant to atherosclerosis are not known. Our combined analysis of 24,320 individuals from 11 populations of white European ethnicity showed an association between coronary artery disease and both the count and the size of ROHs. Individuals with coronary artery disease had approximately 0.63 (95% CI: 0.4–0.8) excess of ROHs when compared to coronary-artery-disease-free control subjects (p = 1.49 × 10−9). The average total length of ROHs was approximately 1,046.92 (95% CI: 634.4–1,459.5) kb greater in individuals with coronary artery disease than control subjects (p = 6.61 × 10−7). None of the identified individual ROHs was associated with coronary artery disease after correction for multiple testing. However, in aggregate burden analysis, ROHs favoring increased risk of coronary artery disease were much more common than those showing the opposite direction of association with coronary artery disease (p = 2.69 × 10−33). Individual ROHs showed significant associations with monocyte and macrophage expression of genes in their close proximity—subjects with several individual ROHs showed significant differences in the expression of 44 mRNAs in monocytes and 17 mRNAs in macrophages when compared to subjects without those ROHs. This study provides evidence for an excess of homozygosity in coronary artery disease in outbred populations and suggest the potential biological relevance of ROHs in cells of importance to the pathogenesis of atherosclerosis.
Objectives The study objective was to determine whether the coronary artery disease (CAD)-associated genotype at chromosome 9p21 modulates basal or induced expression of type I interferons (IFN-I). ...Background The mechanism responsible for the association between common variants in chromosome 9p21.3 and CAD remains unclear. It has been reported that the CAD risk locus is rich in enhancer-like elements and that chromosome looping can lead to its physical proximity with the IFN-I gene cluster, raising the possibility that the locus influences CAD risk by modulating expression of IFN-Is. Methods We examined whether genotype at the lead CAD-associated single nucleotide polymorphism (rs1333049) in 9p21 was associated with: 1) basal levels of IFN-I in plasma from 148 healthy male subjects; 2) induction of IFN-I by Toll-like receptor stimulants in peripheral blood mononuclear cells of 60 healthy volunteers assessed by enzyme-linked immunosorbent assay, quantitative polymerase chain reaction, Western blot, and IFN-I bioassay; and 3) enhancer activity of predicted IFN regulatory factor 3/7 binding sites within the 9p21 CAD risk region in reporter assays. Results No significant effects of 9p21 genotype were observed for plasma levels of IFN-α, IFN-α21, or CXCL10, or leukocyte induction of IFN-α, IFN-α21, IFN-β, CXCL10, or total IFN-I measured at the mRNA, protein, and biological activity levels. There was also no enhancement of reporter activity by predicted IFN regulatory factor 3/7 binding sites in the CAD risk locus of either genotype. Conclusions The mechanism underlying the association between common 9p21 variants and CAD does not involve differential regulation of IFN-I responses.
To investigate the relationship between angiopoietin-like protein 4 (Angptl4) levels, coronary heart disease (CHD) biomarkers, and ANGPTL4 variants.
Plasma Angptl4 was quantified in 666 subjects of ...the Northwick Park Heart Study II using a validated ELISA. Seven ANGPTL4 single-nucleotide polymorphisms were genotyped, and CHD biomarkers were assessed in the whole cohort (N=2775). Weighted mean±SD plasma Angptl4 levels were 10.0±11.0 ng/mL. Plasma Angptl4 concentration correlated positively with age (r=0.15, P<0.001) and body fat mass (r=0.19, P=0.003) but negatively with plasma high-density lipoprotein cholesterol (r=-0.13, P=0.01). No correlation with triglycerides (TGs) was observed. T266M was independently associated with plasma Angptl4 levels (P<0.001) but was not associated with TGs or CHD risk in the meta-analysis of 5 studies (4061 cases/15 395 controls). E40K showed no independent association with plasma Angptl4 levels. In human embryonic kidney 293 and human hepatoma 7 cells compared with wild type, E40K and T266M showed significantly altered synthesis and secretion, respectively.
Circulating Angptl4 levels may not influence TG levels or CHD risk for the following reasons: (1) Angptl4 levels were not correlated with TGs; (2) T266M, although associated with Angptl4 levels, showed no association with plasma TGs; and (3) TG-lowering E40K did not influence Angptl4 levels. These results provide new insights into the role of Angptl4 in TG metabolism.
The kidney plays an important role in salt and blood pressure (BP) homeostasis. In previous studies, variants in the genes for alpha-adducin (ADD1), WNK1, and NEDD4L, which all regulate renal sodium ...absorption, have been associated with increased BP. However, findings have been inconsistent. We tested whether this is because of physiological interactions between the effects of variants in these genes. We assessed the single and combined effects of the ADD1 (Gly460Trp), WNK1 (rs880054 A/G), and NEDD4L (rs4149601 G/A) polymorphisms on renal and BP response to an acute Na load (n=344 subjects), BP decrease after 1 month of treatment with 12.5 mg of hydrochlorothiazide (n=193), and ambulatory 24-hour BP (n=690). Individually, the variants showed modest effects on some of the studied phenotypes. We found the ADD1 Trp allele to be permissive for the effects of variants of the other genes. In combination, the same variants (ADD1 Trp/WNK1 GG/Nedd4L GA+AA) showed a consistent effect on renal Na handling (P=0.009) and acute BP response to a saline infusion (P=0.021), BP lowering after thiazide treatment (P=0.008), and nocturnal systolic BP (P=0.044). Physiological interaction between the ADD1 and WNK1-NEDD4L pathways influences the effects of variants in these genes on sodium-related BP regulation. Relatively common alleles in the ADD1, WNK1, and NEDD4L genes when present in combination may have significant effects on renal sodium handling, BP, and antihypertensive response to thiazides.
Recent genome-wide studies have shown a significant association of a locus on chromosome 9p21.3 and coronary artery disease. We performed a case-control study to investigate the association between ...this locus and abdominal aortic aneurysm (AAA).
A total of 1714 patients (899 patients with AAA and 815 controls) were genotyped for the lead single-nucleotide polymorphism, rs1333049, on chromosome 9p21. The frequency of the C (risk) allele of rs1333049 in the control group was 0.471. There was a significant association between the C allele and AAA (odds ratio, 1.22; 95% confidence interval, 1.06 to 1.39; P=0.004). The genotypic-specific odds ratios (compared with the GG genotype) were 1.17 (95% confidence interval, 0.93 to 1.47; P=0.191) for the GC genotype and 1.50 (95% confidence interval, 1.14 to 1.97; P=0.004) for the CC genotype. In logistic regression modeling, the association of the CC genotype with AAA was independent of the presence of clinical coronary artery disease (odds ratio, 1.46; 95% confidence interval, 1.11 to 1.94; P=0.008).
Our study shows that the recently identified chromosome 9 variant that increases risk of coronary artery disease is also associated with the presence of AAA. The findings suggest that the effect of this locus on risk of cardiovascular disease extends beyond the coronary circulation.