[Show abstract][Hide abstract] ABSTRACT: To identify genetic causes of intellectual disability (ID), we screened a cohort of 986 individuals with moderate to severe ID for variants in 565 known or candidate ID-associated genes using targeted next-generation sequencing. Likely pathogenic rare variants were found in ∼11% of the cases (113 variants in 107/986 individuals: ∼8% of the individuals had a likely pathogenic loss of function (LoF) variant, while ∼3% had a known pathogenic missense variant). Variants in SETD5, ATRX, CUL4B, MECP2 and ARID1B were the most common causes of ID. This study assessed the value of sequencing a cohort of probands to provide a molecular diagnosis of ID, without the availability of DNA from both parents for de novo sequence analysis. This modelling is clinically relevant as 28% of all UK families with dependent children are single parent households. In conclusion, to diagnose patients with ID in the absence of parental DNA, we recommend investigation of all LoF variants in known genes that cause ID and assessment of limited list of proven pathogenic missense variants in these genes. This will provide 11% additional diagnostic yield beyond the 10-15% yield from array CGH alone. This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: Our previous genome-wide association study (GWAS) identified two susceptibility loci for congenital heart disease (CHD) in Han Chinese. Here we identify additional loci by testing promising associations in an extended 3-stage validation consisting of 6,053 CHD cases and 7,410 controls. We find GW significant (P<5.0 × 10(-8)) evidence of 4 additional CHD susceptibility loci at 4q31.22 (rs1400558, upstream of EDNRA, Pall=1.63 × 10(-9)), 9p24.2 (rs7863990, close to SMARCA2, Pall=3.71 × 10(-14)), 12q24.13 (rs2433752, upstream of TBX3 and TBX5, Pall=1.04 × 10(-10)) and 20q12 (rs490514, in PTPRT, Pall=1.20 × 10(-13)). Moreover, the data from previous European GWAS supports that rs490514 is associated with the risk of CHD (P=3.40 × 10(-3)). These results enhance our understanding of CHD susceptibility.
No preview · Article · Aug 2015 · Nature Communications
[Show abstract][Hide abstract] ABSTRACT: Lymphocytes contribute to ischemia/reperfusion (I/R) injury in several organ systems, but their relevance in ST elevation myocardial infarction (STEMI) is unknown. Our goal was to characterize lymphocyte dynamics in individuals after primary percutaneous coronary intervention (PPCI), assess the prognostic relevance of these cells, and explore mechanisms of lymphocyte-associated injury.
Lymphocyte counts were retrospectively analyzed in 1,377 STEMI patients, and the prognostic relevance of post-PPCI lymphopenia was assessed by Cox proportional hazards regression. Blood from 59 prospectively recruited STEMI patients undergoing PPCI was sampled, and leukocyte subpopulations were quantified. Microvascular obstruction (MVO), a component of I/R injury, was assessed using MRI.
In the retrospective cohort, lymphopenia was associated with a lower rate of survival at 3 years (82.8% vs. 96.3%, lowest vs. highest tertile; hazard ratio 2.42). In the prospective cohort, lymphocyte counts fell 90 minutes after reperfusion, primarily due to loss of T cells. CD8+ T cells decreased more than CD4+ T cells, and effector subsets exhibited the largest decline. The early decrease in effector T cell levels was greater in individuals that developed substantial MVO. The drop in T cell subsets correlated with expression of the fractalkine receptor CX3CR1 (r2 = 0.99, P = 0.006). Serum fractalkine concentration peaked at 90 minutes after reperfusion, coinciding with the T cell count nadir.
Lymphopenia following PPCI is associated with poor prognosis. Our data suggest that fractalkine contributes to lymphocyte shifts, which may influence development of MVO through the action of effector T cells.
British Heart Foundation (FS/12/31/29533) and National Institute of Health Research (NIHR) Newcastle Biomedical Research Centre.
Full-text · Article · Jul 2015 · The Journal of clinical investigation
[Show abstract][Hide abstract] ABSTRACT: Aims
This study aims to evaluate temporal changes in stroke complications and their association with mortality and MACE outcomes in a national cohort of patients undergoing percutaneous coronary interventions (PCIs) in England and Wales.
Methods and results
A total of 426 046 patients who underwent PCI in England and Wales between 2007 and 2012 in the British Cardiovascular Intervention Society (BCIS) database were analysed. Statistical analyses were performed evaluating the rates of stroke complications according to the year of PCI and multiple logistic regressions were used to evaluate the odds of 30-day mortality and in-hospital major adverse cardiovascular events (MACE; a composite of in-hospital mortality, myocardial infarction or re-infarction, and revascularization) with stroke complications. Four hundred and thirty-six patients (0.1%) sustained an ischaemic stroke/TIA complication and 107 patients (0.03%) sustained a haemorrhagic stroke complication. Ischaemic stroke/TIA complications increased non-linearly from 0.67 (95% CI 0.47–0.87) to 1.14 (0.94–1.34) per 1000 patients between 2007 and 2012 (P = 0.006), whilst haemorrhagic stroke rates decreased non-linearly from 0.29 (0.19–0.39) to 0.15 (0.05–0.25) per 1000 patients in 2012 (P = 0.009). Following adjustment for baseline clinical and procedural demographics, ischaemic stroke was independently associated with both 30-day mortality (OR 4.92, 3.06–7.92) and in-hospital MACE (OR 3.11, 1.83–5.27). An even greater impact on prognosis was observed with haemorrhagic complications (30-day mortality: OR 13.87, 6.37–30.21), in-hospital MACE (OR 13.50, 6.30–28.92).
Incident ischaemic stroke complications have increased over time, whilst haemorrhagic stroke complications have decreased, driven through changes in clinical, procedural, drug-treatment, and demographic factors. Both ischaemic and haemorrhagic strokes are rare but devastating complications with high 30-day mortality and in-hospital MACE rates.
No preview · Article · Apr 2015 · European Heart Journal
[Show abstract][Hide abstract] ABSTRACT: Background Truncus arteriosus (TA) is characterised by failure of septation of the outflow tract into aortic and pulmonary trunks and is associated with high morbidity and mortality. Although ranked among the least common congenital heart defects, TA provides an excellent model for the role of individual genes in cardiac morphogenesis as exemplified by TBX1 deficiency caused by point mutations or, more commonly, hemizygosity as part of the 22q11.2 deletion syndrome. The latter genetic lesion, however, is only observed in a proportion of patients with TA, which suggests the presence of additional disease genes.
Objective To identify novel genes that cause Mendelian forms of TA.
Methods and results We exploited the occurrence of monogenic forms of TA in the Saudi population, which is characterised by high consanguinity, a feature conducive to the occurrence of Mendelian phenocopies of complex phenotypes as we and others have shown. Indeed, we demonstrate in two multiplex consanguineous families that we are able to map TA to regions of autozygosity in which whole-exome sequencing revealed homozygous truncating mutations in PRKD1 (encoding a kinase derepressor of MAF2) and NRP1 (encoding a coreceptor of vascular endothelial growth factor (VEGFA)). Previous work has demonstrated that Prkd1−/− is embryonic lethal and that its tissue-specific deletion results in abnormal heart remodelling, whereas Nrp1−/− develops TA. Surprisingly, molecular karyotyping to exclude 22q11.2 deletion syndrome in the replication cohort of 17 simplex TA cases revealed a de novo hemizygous deletion that encompasses PRDM1, deficiency of which also results in TA phenotype in mouse.
Conclusions Our results expand the repertoire of molecular lesions in chromatin remodelling and transcription factors that are implicated in the pathogenesis of congenital heart disease in humans and attest to the power of monogenic forms of congenital heart diseases as a complementary approach to dissect the genetics of these complex phenotypes.
Full-text · Article · Feb 2015 · Journal of Medical Genetics
[Show abstract][Hide abstract] ABSTRACT: Background
The ZFHX3 gene, located in Chromosome 16q22.3, codes for a transcription factor which is widely expressed in human tissues. Genome-wide studies have identified associations between variants within the gene and Kawasaki disease and atrial fibrillation. ZFHX3 has two main transcripts that utilise different transcription start sites. We examined the association between genetic variants in the 16q22.3 region and expression of ZFHX3 to identify variants that regulate gene expression.ResultsWe genotyped 65 single-nucleotide polymorphisms to tag genetic variation at the ZFHX3 locus in two cohorts, 451 British individuals recruited in the North East of England and 310 mixed-ancestry individuals recruited in South Africa. Allelic expression analysis revealed that the minor (A) allele of rs8060701, a variant in the first intron of ZFHX3, was associated with a 1.16-fold decrease in allelic expression of both transcripts together, (p¿=¿4.87e-06). The minor (C) allele of a transcribed variant, rs10852515, in the second exon of ZFHX3 isoform A was independently associated with a 1.36-fold decrease in allelic expression of ZFHX3 A (p¿=¿7.06e-31), but not overall ZFHX3 expression. However, analysis of total gene expression of ZFHX3 failed to detect an association with genotype at any variant. Differences in linkage disequilibrium between the two populations allowed fine-mapping of the locus to a 7 kb region overlapping exon 2 of ZFHX3 A. We did not find any association between ZFHX3 expression and any of the variants identified by genome wide association studies.Conclusions ZFHX3 transcript levels are regulated in a transcript-specific fashion by independent cis-acting transcribed polymorphisms. Our results demonstrate the power of allelic expression analysis and trans-ethnic fine mapping to identify transcript-specific cis-acting regulatory elements .
[Show abstract][Hide abstract] ABSTRACT: Rationale:
There is mounting evidence of a higher incidence of coronary heart disease in cytomegalovirus-seropositive individuals.
The aim of this study was to investigate whether acute myocardial infarction triggers an inflammatory T-cell response that might lead to accelerated immunosenescence in cytomegalovirus-seropositive patients.
Methods and results:
Thirty-four patients with acute myocardial infarction undergoing primary percutaneous coronary intervention were longitudinally studied within 3 months after reperfusion (Cohort A). In addition, 54 patients with acute myocardial infarction and chronic myocardial infarction were analyzed in a cross-sectional study (Cohort B). Cytomegalovirus-seropositive patients demonstrated a greater fall in the concentration of terminally differentiated CD8 effector memory T cells (TEMRA) in peripheral blood during the first 30 minutes of reperfusion compared with cytomegalovirus-seronegative patients (-192 versus -63 cells/μL; P=0.008), correlating with the expression of programmed cell death-1 before primary percutaneous coronary intervention (r=0.8; P=0.0002). A significant proportion of TEMRA cells remained depleted for ≥3 months in cytomegalovirus-seropositive patients. Using high-throughput 13-parameter flow cytometry and human leukocyte antigen class I cytomegalovirus-specific dextramers, we confirmed an acute and persistent depletion of terminally differentiated TEMRA and cytomegalovirus-specific CD8(+) cells in cytomegalovirus-seropositive patients. Long-term reconstitution of the TEMRA pool in chronic cytomegalovirus-seropositive postmyocardial infarction patients was associated with signs of terminal differentiation including an increase in killer cell lectin-like receptor subfamily G member 1 and shorter telomere length in CD8(+) T cells (2225 versus 3397 bp; P<0.001).
Myocardial ischemia and reperfusion in cytomegalovirus-seropositive patients undergoing primary percutaneous coronary intervention leads to acute loss of antigen-specific, terminally differentiated CD8 T cells, possibly through programmed cell death-1-dependent programmed cell death. Our results suggest that acute myocardial infarction and reperfusion accelerate immunosenescence in cytomegalovirus-seropositive patients.
Full-text · Article · Nov 2014 · Circulation Research
[Show abstract][Hide abstract] ABSTRACT: Statins are one of the most potent drugs in delaying age-related inflammatory changes in the arterial vessel wall, slowing down the progression of atherosclerosis. Statins have also been shown to abrogate telomere-attributed cardiovascular risk. The goal of our study was to explore a potential effect of atorvastatin on telomerase activity in peripheral blood mononuclear cells (PBMCs) and T-lymphocytes (T cells).
Methods and Results
Treatment with pharmacologically relevant concentrations (0.1-0.3 μM) of atorvastatin resulted in a 6-fold increase of telomerase activity (TA) (p<0.0001) in human and mouse PBMCs and CD4 T cells, translating into moderate proliferation of T lymphocytes. In contrast, high doses of atorvastatin (2 - 5 μM) or the addition of LDL cholesterol completely inhibited proliferation, thereby abrogating telomerase activity. The proliferative effect of atorvastatin was ablated by the absense of the catalytic subunit of telomerase, telomerase reverse transcriptase (TERT). Using transgenic GFP-mTert reporter mice, we observed a decrease in telomerase-positive lymphocytes from 30% to 15% during the first 5 months of age (p<0.01). This suggests that the decrease in immune cell turnover during normal development and maturation is mirrored by a reduction in telomerase activity in lymphocytes in-vivo.
Atorvastatin and cholesterol have opposing effects on telomerase in mononuclear cells and T-lymphocytes. Our study suggests a link between cholesterol metabolism and telomere-related cardiovascular risk.
[Show abstract][Hide abstract] ABSTRACT: Guidelines advocate using B-type natriuretic peptides in the diagnostic work-up of suspected heart failure (HF). Their main role is to limit echocardiography rates by ruling out HF/LV dysfunction where peptide level is low. Recommended rule-out cut points vary between guidelines. The utility of B-type natriuretic peptides in the very old (85+) requires further investigation, with optimal cut points yet to be established. We examined NT-proBNP's utility, alone and in combination with history of myocardial infarction (MI), as a rule-out test for LV dysfunction in very old people with limiting dyspnoea.
Design: Cross-sectional analysis.
Setting: Population-based sample; North-East England.
Participants: 155 people (aged 87-89) with limiting dyspnoea.
Measures: Dyspnoea assessed by questionnaire. Domiciliary echocardiography performed; LV systolic/diastolic function graded. NT-proBNP measured (Roche Diagnostics). Receiver operating characteristic analyses examined NT-proBNP's diagnostic accuracy for LV dysfunction.
AUC for LVEF less than or equal to 50% was poor (0.58, 95% CI 0.49-0.65), but good for LVEF less than or equal to 40% (0.80, 95% CI 0.73-0.86). At ESC cut point (125ng/l), few cases of systolic dysfunction were missed (NPV 94-100%, depending on severity), but echocardiography (88%) and false positive rates (56-81 per 100 screened) were high. At NICE cut point (400ng/l), echocardiography (51%) and false positive rates (33-45) were lower; exclusionary performance was good for LVEF less than or equal to 40% (1 case missed per 100 screened, 15% of cases; NPV 97%), but poor for LVEF less than or equal to 50% (16 cases missed per 100 screened, 45% of cases; NPV 68%). Incorporating isolated moderate/severe diastolic dysfunction into target condition increased the proportion of cases missed (lower NPV), whilst improving case detection. Incorporating MI history as an additional referral prompt slightly reduced the number of cases missed at expense of higher echocardiography and false positive rates.
High echocardiography rates and poor exclusionary performance for mild degrees of systolic dysfunction and for diastolic dysfunction limit NT-proBNP's utility as a rule-out test for LV dysfunction in very old people with limiting dyspnoea. Incorporating MI history as an additional echocardiography prompt yields no overall benefit compared to using NT-proBNP level alone.
[Show abstract][Hide abstract] ABSTRACT: Motivation: During the past 4 years, whole-exome sequencing has become a standard tool for finding rare variants causing Mendelian disorders. In that time, there has also been a proliferation of both sequencing platforms and approaches to analyse their output. This requires approaches to assess the performance of different methods. Traditionally, criteria such as comparison with microarray data or a number of known polymorphic sites have been used. Here we expand such approaches, developing a maximum likelihood framework and using it to estimate the sensitivity and specificity of whole-exome sequencing data.
Results: Using whole-exome sequencing data for a panel of 19 individuals, we show that estimated sensitivity and specificity are similar to those calculated using microarray data as a reference. We explore the effect of frequency misspecification arising from using an inappropriately selected population and find that, although the estimates are affected, the rankings across procedures remain the same.
Availability and implementation: An implementation using Perl and R can be found at busso.ncl.ac.uk (Username: igm101; Password: Z1z1nts).
Contact: Darren.Houniet@ogt.com; firstname.lastname@example.org
[Show abstract][Hide abstract] ABSTRACT: Alternative splicing-the production of multiple messenger RNA isoforms from a single gene-is regulated in part by RNA binding proteins. While the RBPs transformer2 alpha (Tra2α) and Tra2β have both been implicated in the regulation of alternative splicing, their relative contributions to this process are not well understood. Here we find simultaneous-but not individual-depletion of Tra2α and Tra2β induces substantial shifts in splicing of endogenous Tra2β target exons, and that both constitutive and alternative target exons are under dual Tra2α-Tra2β control. Target exons are enriched in genes associated with chromosome biology including CHEK1, which encodes a key DNA damage response protein. Dual Tra2 protein depletion reduces expression of full-length CHK1 protein, results in the accumulation of the DNA damage marker γH2AX and decreased cell viability. We conclude Tra2 proteins jointly control constitutive and alternative splicing patterns via paralog compensation to control pathways essential to the maintenance of cell viability.
[Show abstract][Hide abstract] ABSTRACT: Objective
Rare variants in certain transcription factors involved in cardiac development cause Mendelian forms of congenital heart disease. The purpose of this study was to systematically assess the frequency of rare transcription factor variants in sporadic patients with the cardiac outflow tract malformation tetralogy of Fallot (TOF).
Methods and Results
We sequenced the coding, 5′UTR, and 3′UTR regions of twelve transcription factor genes implicated in cardiac outflow tract development (NKX2.5, GATA4, ISL1, TBX20, MEF2C, BOP/SMYD1, HAND2, FOXC1, FOXC2, FOXH, FOXA2 and TBX1) in 93 non-syndromic, non-Mendelian TOF cases. We also analysed Illumina Human 660W-Quad SNP Array data for copy number variants in these genes; none were detected. Four of the rare variants detected have previously been shown to affect transactivation in in vitro reporter assays: FOXC1 p.P297S, FOXC2 p.Q444R, FOXH1 p.S113T and TBX1 p.P43_G61del PPPPRYDPCAAAAPGAPGP. Two further rare variants, HAND2 p.A25_A26insAA and FOXC1 p.G378_G380delGGG, A488_491delAAAA, affected transactivation in in vitro reporter assays. Each of these six functionally significant variants was present in a single patient in the heterozygous state; each of the four for which parental samples were available were maternally inherited. Thus in the 93 TOF cases we identified six functionally significant mutations in the secondary heart field transcriptional network.
This study indicates that rare genetic variants in the secondary heart field transcriptional network with functional effects on protein function occur in 3–13% of patients with TOF. This is the first report of a functionally significant HAND2 mutation in a patient with congenital heart disease.