Genetic susceptibility to acute rheumatic fever: a systematic review and meta-analysis of twin studies

Background

Acute rheumatic fever is considered to be a heritable condition, but the magnitude of the genetic effect is unknown. The objective of this study was to conduct a systematic review and meta-analysis of twin studies of concordance of acute rheumatic fever in order to derive quantitative estimates of the size of the genetic effect.

Methods

We searched PubMed/MEDLINE, ISI Web of Science, EMBASE, and Google Scholar from their inception to 31 January 2011, and bibliographies of retrieved articles, for twin studies of the concordance for acute rheumatic fever or rheumatic heart disease in monozygotic versus dizygotic twins that used accepted diagnostic criteria for acute rheumatic fever and zygosity without age, gender or language restrictions. Twin similarity was measured by probandwise concordance rate and odds ratio (OR), and aggregate probandwise concordance risk was calculated by combining raw data from each study. ORs from separate studies were combined by random-effects meta-analysis to evaluate association between zygosity status and concordance. Heritability was estimated by fitting a variance components model to the data.

Results

435 twin pairs from six independent studies met the inclusion criteria. The pooled probandwise concordance risk for acute rheumatic fever was 44% in monozygotic twins and 12% in dizygotic twins, and the association between zygosity and concordance was strong (OR 6.39; 95% confidence interval, 3.39 to 12.06; P<0.001), with no significant study heterogeneity (P = 0.768). The estimated heritability across all the studies was 60%.

Conclusions

Acute rheumatic fever is an autoimmune disorder with a high heritability. The discovery of all genetic susceptibility loci through whole genome scanning may provide a clinically useful genetic risk prediction tool for acute rheumatic fever and its sequel, rheumatic heart disease.

Four genetic loci influencing electrocardiographic indices of left ventricular hypertrophy

BACKGROUND

Presence of left ventricular hypertrophy on an ECG (ECG-LVH) is widely assessed clinically and provides prognostic information in some settings. There is evidence for significant heritability of ECG-LVH. We conducted a large-scale gene-centric association analysis of 4 commonly measured indices of ECG-LVH.

METHODS AND RESULTS

We calculated the Sokolow-Lyon index, Cornell product, 12-lead QRS voltage sum, and 12-lead QRS voltage product in 10 256 individuals from 3 population-based cohorts and typed their DNA using a customized gene array (the Illumina HumanCVD BeadChip 50K array), containing 49 094 genetic variants in ≈2100 genes of cardiovascular relevance. We followed-up promising associations in 11 777 additional individuals. We identified and replicated 4 loci associated with ECG-LVH indices: 3p22.2 (SCN5A, rs6797133, P=1.22 × 10(-7)) with Cornell product and 12q13.3 (PTGES3, rs2290893, P=3.74 × 10(-8)), 15q25.2 (NMB, rs2292462, P=3.23 × 10(-9)), and 15q26.3 (IGF1R, rs4966014, P=1.26 × 10(-7)) with the 12-lead QRS voltage sum. The odds ratio of being in the top decile for the 12-lead QRS voltage sum for those carrying 6 trait-raising alleles at the 12q13.3, 15q25.2, and 15q26.3 loci versus those carrying 0 to 1 alleles was 1.60 (95% CI: 1.20 to 2.29). Lead single-nucleotide polymorphisms at the 12q13.3 and 15q25.2 loci showed significant expression quantitative trait loci effects in monocytes.

CONCLUSIONS

These findings provide novel insights into the genetic determination of ECG-LVH. The findings could help to improve our understanding of the mechanisms determining this prognostically important trait.

A systematic overview of prospective cohort studies of cardiovascular disease in sub-Saharan Africa

Background

Cardiovascular diseases (CVDs) are becoming increasingly significant in sub-Saharan Africa (SSA). Reliable measures of the contribution of major determinants are essential for informing health services and policy solutions.

Objective

To perform a systematic review of all longitudinal studies of CVDs and related risk factors that have been conducted in SSA.

Data source

We searched electronic databases from 1966 to October 2009. Published studies were retrieved from PubMed and Africa EBSCO. Reference lists of identified articles were scanned for additional publications.

Study selection

Any longitudinal study with data collection at baseline on major cardiovascular risk factors or CVD, including 30 or more participants, and with at least six months of follow up were included.

Data extraction

Data were extracted on the country of study, year of inception, baseline evaluation, primary focus of the study, outcomes, and number of participants at baseline and final evaluation.

Results

Eighty-one publications relating to 41 studies from 11 SSA countries with a wide range of participants were included. Twenty-two were historical/prospective hospital-based studies. These studies focused on risk factors, particularly diabetes mellitus and hypertension, or CVD including stroke, heart failure and rheumatic heart disease. The rate of participants followed through the whole duration of studies was 72% (64–80%), with a significant heterogeneity between studies (for heterogeneity, p < 0.001). Outcomes monitored during follow up included trajectories of risk markers and mortality.

Conclusions

Well-designed prospective cohort studies are needed to inform and update our knowledge regarding the epidemiology CVDs and their interactions with known risk factors in the context of common infectious diseases in this region.

Genotype at the P554L variant of the hexose-6 phosphate dehydrogenase gene is associated with carotid intima-medial thickness

OBJECTIVE

The combined thickness of the intima and media of the carotid artery (carotid intima-medial thickness, CIMT) is associated with cardiovascular disease and stroke. Previous studies indicate that carotid intima-medial thickness is a significantly heritable phenotype, but the responsible genes are largely unknown. Hexose-6 phosphate dehydrogenase (H6PDH) is a microsomal enzyme whose activity regulates corticosteroid metabolism in the liver and adipose tissue; variability in measures of corticosteroid metabolism within the normal range have been associated with risk factors for cardiovascular disease. We performed a genetic association study in 854 members of 224 families to assess the relationship between polymorphisms in the gene coding for hexose-6 phosphate dehydrogenase (H6PD) and carotid intima-medial thickness.

METHODS

Families were ascertained via a hypertensive proband. CIMT was measured using B-mode ultrasound. Single nucleotide polymorphisms (SNPs) tagging common variation in the H6PD gene were genotyped. Association was assessed following adjustment for significant covariates including "classical" cardiovascular risk factors. Functional studies to determine the effect of particular SNPs on H6PDH were performed.

RESULTS

There was evidence of association between the single nucleotide polymorphism rs17368528 in exon five of the H6PD gene, which encodes an amino-acid change from proline to leucine in the H6PDH protein, and mean carotid intima-medial thickness (p = 0.00065). Genotype was associated with a 5% (or 0.04 mm) higher mean carotid intima-medial thickness measurement per allele, and determined 2% of the population variability in the phenotype.

CONCLUSIONS

Our results suggest a novel role for the H6PD gene in atherosclerosis susceptibility.

Clinical characteristics and outcomes of familial and idiopathic dilated cardiomyopathy in Cape Town: a comparative study of 120 cases followed up over 14 years

BACKGROUND

It is not known whether there are differences in clinical characteristics and outcomes of patients with familial and idiopathic dilated cardiomyopathy (DCM) in an African setting.

PURPOSE

To compare the clinical characteristics and outcomes of familial and idiopathic DCM.

METHODS

We performed a retrospective study of familial and idiopathic DCM at Groote Schuur Hospital, Cape Town, between 1 February 1996 and 31 December 2009. Clinical, electrocardiographic (ECG) and imaging characteristics were compared, in addition to treatment and survival.

RESULTS

Eighty patients with idiopathic DCM and 40 familial cases were studied. ECG T-wave inversion was significantly more frequent in familial DCM (87.5%) than in idiopathic cases (68.8%) (p=0.014), whereas idiopathic patients had a higher prevalence of pathological Q waves (32.5%) than familial cases (12.5%) (p=0.028). Cardiac chambers were significantly more dilated with poorer systolic function in idiopathic than familial cases. A mortality rate of 40% after a median follow-up of 5 years was, however, similar in both groups. The presence of New York Heart Association functional class III and IV symptoms was an independent predictor of mortality (odds ratio (OR) 3.85, 95% confidence interval (CI) 1.30 - 48.47, p<0.001), while heart transplantation was an independent predictor of survival (OR 4.72, 95% CI 1.31 - 72.60, p=0.026) in both groups. Digoxin use without serum monitoring was a significant predictor of mortality in idiopathic DCM (OR 1.62, 95% CI 1.04 - 3.98, p=0.037).

CONCLUSION

Patients with idiopathic DCM have greater cardiac dysfunction than those with familiar disease, but mortality is similarly high in both groups. Digoxin use without drug level monitoring may be associated with increased mortality in idiopathic DCM.

Frequency and clinical genetics of familial dilated cardiomyopathy in Cape Town: implications for the evaluation of patients with unexplained cardiomyopathy

BACKGROUND

Studies from Europe and North America suggest that 20 - 50% of patients with dilated cardiomyopathy (DCM) may have familial disease. There is little information on the frequency and clinical genetics of familial DCM in Africa.

PURPOSE

To determine the frequency and probable mode of inheritance of familial DCM in patients referred for investigation of the cause of DCM at a tertiary centre in Cape Town.

METHODS

We conducted a retrospective analysis of consecutive patients diagnosed with DCM between 1 February 1996 and 31 December 2009 to determine the frequency of familial disease.

RESULTS

Of 109 unrelated patients with DCM, 29 (26.6%) had familial disease. Their mean age of onset of cardiomyopathy (28.01 (standard deviation (SD) 15.33) years) was significantly younger than that for non-familial cases (39.1 (SD 12.6) years) (p=0.001). Male predominance (N=21, 72.4%) and racial distribution (15 (48.3%) coloured patients, 10 (34.5%) black Africans, 4 (13.8%) white individuals, and 1 (3.4%) of Indian descent) of familial DCM probands were similar to the non-familial cases. Of the 29 patients with familial DCM, 2 (7%) had at least one relative diagnosed with peripartum cardiomyopathy. Pedigree analysis of the 29 families was consistent with autosomal dominant inheritance in 72.4%, autosomal recessive inheritance in 17.2% and X-linked recessive inheritance in 10.4%.

CONCLUSIONS

Familial DCM affects at least a quarter of African patients with DCM, presents at a young age, is associated with peripartum cardiomyopathy, and follows an autosomal dominant pattern of inheritance in the majority of families. Family screening for familial DCM is indicated in all cases of unexplained DCM, including patients with peripartum cardiomyopathy.

Common Variation at the 11-β Hydroxysteroid Dehydrogenase Type 1 Gene Is Associated With Left Ventricular Mass

Background—

Polymorphisms in 11-β hydroxysteroid dehydrogenase type 1 (11β-HSD1, encoded by HSD11B1 ) have been reported to be associated with obesity-related cardiovascular risk factors, such as type II diabetes and hypertension. Left ventricular hypertrophy (LVH) is an independent risk factor for cardiovascular death associated with these factors but has significant additional heritability, the cause of which is undetermined. The 11β-HSD1 is believed to maintain tonic inhibition of the mineralocorticoid receptor in cardiomyocytes, and mineralocorticoid receptor activation is involved in the pathophysiology of LVH. We assessed the association between polymorphisms in the HSD11B1 gene and left ventricular mass (LVM) in 248 families ascertained through a proband with hypertension.

Methods and Results—

LVM was measured by electrocardiography and echocardiography in 868 and 829 participants, respectively. Single-nucleotide polymorphisms (SNPs) tagging common variation in the HSD11B1 gene were genotyped by mass spectrometry. The rs846910 SNP, which lies in the flanking region 5′ to exon 1B of HSD11B1 , was associated with LVM both by electrocardiography (≈5% lower LVM per copy of the rare allele, P =0.02) and by echocardiography (≈10% lower LVM per copy of the rare allele, P =0.003). Genotype explained 1% to 2% of the population variability in LVM, or approximately 5% of the heritable fraction. There were no significant associations between any HSD11B1 SNP and blood pressure or body mass index that could have confounded the association with LVM.

Conclusions—

Genotype at HSD11B1 has a small, but significant effect on LVM, apparently independently of any effect on obesity-related traits. These findings suggest a novel action of 11β-HSD1 in the human cardiomyocyte, which may be of therapeutic importance.

Triage and management of pericardial effusion

Pericardial effusion may be detected as an incidental finding during echocardiography or following a diagnostic imaging study for a symptomatic patient. When a pericardial effusion is detected the first step is to assess its size, hemodynamic importance, and possible associated diseases. The more common causes of pericardial effusions include infections (viral, bacterial, especially tuberculosis), cancer, connective tissue diseases, pericardial injury syndromes, metabolic causes (i.e. hypothyroidism), myopericardial and aortic diseases. The relative frequency of different causes depends on the local epidemiology, the hospital setting and the diagnostic protocol that has been adopted. Many cases still remain idiopathic in developed countries, whereas tuberculosis is the dominant cause in developing countries. Specific testing should be performed according to clinical suspicion. The presence of elevated inflammatory markers and other criteria (chest pain, pericardial rubs, ECG changes) suggest pericarditis and management should be directed accordingly. Treatment should be targeted at the etiology as much as possible. Nevertheless, when diagnosis is still unclear, or idiopathic and inflammatory markers are elevated, empiric anti-inflammatory therapy may be worthwhile. A true isolated effusion may not require a specific treatment if the patient is asymptomatic, but large ones have a theoretical risk of progression to cardiac tamponade (up to one-third) if subacute with signs of right-sided collapse, and especially chronic (>3 months). Pericardiocentesis alone may be curative for large effusions but recurrences are also common and pericardiectomy or less invasive options (i.e. pericardial window) should be considered whenever fluid re-accumulates (especially with tamponade), becomes loculated, or biopsy material is required.

Medical therapy of pericardial diseases: part I: idiopathic and infectious pericarditis

The treatment of pericardial diseases is largely empirical because of the relative lack of randomized trials compared with other cardiovascular diseases. The main forms of pericardial diseases that can be encountered in the clinical setting include acute and recurrent pericarditis, pericardial effusion with or without cardiac tamponade, and constrictive pericarditis. Medical treatment should be targeted at the cause of the disease as much as possible. However, the cause of pericardial diseases may be varied and depends on the prevalence of specific diseases (especially tuberculosis). The search for an etiology is often inconclusive, and most cases are classified as idiopathic in developed countries where tuberculosis is relatively rare, whereas a tuberculous etiology is often presumed in developing countries where tuberculosis is endemic. The aim of the present article is to review current medical therapy for pericardial diseases, highlighting recent significant advances in clinical research, ongoing challenges and unmet needs. Following a probabilistic approach, the most common causes are considered (idiopathic, viral, tuberculous, purulent, connective tissue diseases and neoplastic pericardial disease). In this article, the therapy of idiopathic and more common forms of infectious pericarditis (viral and bacterial) is reviewed.

Medical therapy of pericardial diseases: part II: Noninfectious pericarditis, pericardial effusion and constrictive pericarditis

The treatment of pericardial diseases is largely empirical because of the relative lack of randomized trials compared with other cardiovascular diseases. The main forms of pericardial diseases that can be encountered in the clinical setting include acute and recurrent pericarditis, pericardial effusion with or without cardiac tamponade, and constrictive pericarditis. Medical treatment should be targeted at the cause as much as possible. In this article, the therapy of more common forms of noninfectious pericarditis (pericarditis in systemic autoimmune diseases and neoplastic pericardial disease), pericardial effusion, and constrictive pericarditis is reviewed.

Coronary artery disease-related genetic variant on chromosome 10q11 is associated with carotid intima-media thickness and atherosclerosis

OBJECTIVE

To investigate whether chromosome 10q11.21 influences common carotid intima-media thickness (IMT) and atherosclerosis and whether it is associated with stromal cell-derived factor-1α (SDF-1α) plasma levels.

METHODS AND RESULTS

Variation on chromosome 10q11.21 has been consistently associated with coronary artery disease. The genetic variant lies upstream of the gene encoding SDF-1α. We genotyped 3 population cohorts (Bruneck [age range, 45 to 94 years; 50.0% men; n=738], Health2000 [age range, 46 to 76 years; 55.4% men; n=1237], and essential hypertension in families collected in the region of Oxford [HTO] [age range, 19 to 88 years; 47.9% men; n=770]) for single-nucleotide polymorphism rs501120 at the 10q11.21 locus and conducted a meta-analysis in these cohorts to ascertain a relationship between the polymorphism and carotid IMT. The analysis showed that individuals with the T/T genotype had a significantly higher carotid IMT than individuals with the C/T or C/C genotype (pooled weighted mean difference, 23 μm [95% CI, 9 to 37 μm], P=0.0014 under a fixed-effects model; and 23 μm [95% CI, 6 to 41 μm], P=0.009 under a random-effects model). In the Bruneck cohort, in which data for carotid atherosclerosis and plasma SDF-1α levels were available, we observed an association of the T/T genotype with a higher burden of atherosclerosis and increased susceptibility to the development of atherosclerosis during a 5-year follow-up (multivariable odds ratio, 1.73 [95% CI, 1.18 to 2.52]; P=0.005 for the recessive model) and an association between the T/T genotype and lower SDF-1α levels (2.62 ng/mL for T/T versus 2.74 ng/mL for C/C or C/T; P=0.023).

CONCLUSIONS

The coronary heart disease-related variant at the 10q11.21 locus is associated with carotid IMT and atherosclerosis.

Chromosome 9p21 SNPs Associated with Multiple Disease Phenotypes Correlate with ANRIL Expression

Single nucleotide polymorphisms (SNPs) on chromosome 9p21 are associated with coronary artery disease, diabetes, and multiple cancers. Risk SNPs are mainly non-coding, suggesting that they influence expression and may act in cis. We examined the association between 56 SNPs in this region and peripheral blood expression of the three nearest genes CDKN2A, CDKN2B, and ANRIL using total and allelic expression in two populations of healthy volunteers: 177 British Caucasians and 310 mixed-ancestry South Africans. Total expression of the three genes was correlated (P<0.05), suggesting that they are co-regulated. SNP associations mapped by allelic and total expression were similar (r = 0.97, P = 4.8×10⁻⁹⁹), but the power to detect effects was greater for allelic expression. The proportion of expression variance attributable to cis-acting effects was 8% for CDKN2A, 5% for CDKN2B, and 20% for ANRIL. SNP associations were similar in the two populations (r = 0.94, P = 10⁻⁷²). Multiple SNPs were independently associated with expression of each gene (P<0.05 after correction for multiple testing), suggesting that several sites may modulate disease susceptibility. Individual SNPs correlated with changes in expression up to 1.4-fold for CDKN2A, 1.3-fold for CDKN2B, and 2-fold for ANRIL. Risk SNPs for coronary disease, stroke, diabetes, melanoma, and glioma were all associated with allelic expression of ANRIL (all P<0.05 after correction for multiple testing), while association with the other two genes was only detectable for some risk SNPs. SNPs had an inverse effect on ANRIL and CDKN2B expression, supporting a role of antisense transcription in CDKN2B regulation. Our study suggests that modulation of ANRIL expression mediates susceptibility to several important human diseases.

Genetic variants on chromosome 9p21 have been associated with several important diseases including coronary artery disease, diabetes, and multiple cancers. Most of the risk variants in this region do not alter any protein sequence and are therefore likely to act by influencing the expression of nearby genes. We investigated whether chromosome 9p21 variants are correlated with expression of the three nearest genes (CDKN2A, CDKN2B, and ANRIL) which might mediate the association with disease. Using two different techniques to study effects on expression in blood from two separate populations of healthy volunteers, we show that variants associated with disease are all correlated with ANRIL expression, but associations with the other two genes are weaker and less consistent. Multiple genetic variants are independently associated with expression of all three genes. Although total expression levels of CDKN2A, CDKN2B, and ANRIL are positively correlated, individual genetic variants influence ANRIL and CDKN2B expression in opposite directions, suggesting a possible role of ANRIL in CDKN2B regulation. Our study suggests that modulation of ANRIL expression mediates susceptibility to several important human diseases.

Novel therapeutic concepts: the epidemic of cardiovascular disease in the developing world: global implications

The epidemic of cardiovascular disease (CVD) is a global phenomenon, and the magnitude of its increase in incidence and prevalence in low- and middle-income countries (LIMIC) has potentially major implications for those high-income countries that characterize much of the developed world. Cardiovascular disease remains the leading cause of death in the world and approximately 80% of all cardiovascular-related deaths occur in LIMIC and at a younger age in comparison to high-income countries. The economic impact in regard to loss of productive years of life and the need to divert scarce resources to tertiary care is substantial. The 'epidemiologic transition' provides a useful framework for understanding changes in the patterns of disease as a result of societal and socioeconomic developments in different countries and regions of the world. A burning but as yet unanswered question is whether gains made over the last four decades in reducing cardiovascular mortality in high-income countries will be offset by changes in risk factor profiles, and in particular obesity and diabetes. Much of the population attributable risk of myocardial infarction is accountable on the basis of nine modifiable traditional risk factors, irrespective of geography. Developing societies are faced with a hostile cardiovascular environment, characterized by changes in diet, exercise, the effects of tobacco, socioeconomic stressors, and economic constraints at both the national and personal level in addition to exposure to potential novel risk factors and perhaps a genetic or programmed foetal vulnerability to CVD in later life. There are major challenges for primary and secondary prevention including lack of data, limited national resources, and the lack of prediction models in certain populations. There are two major approaches to prevention: public health/community-based strategies and clinic-based with a targeted approach to high-risk patients and combinations of these. There are concerns that in comparison with communicable diseases, cardiovascular and chronic diseases have a relatively low priority in the global health agenda and that this requires additional emphasis. The human race has had long experience and a fine tradition in surviving adversity, but we now face a task for which we have little experience, the task of surviving prosperity Alan Gregg 1890-1957, Rockefeller Foundation.

STK39 polymorphisms and blood pressure: an association study in British Caucasians and assessment of cis-acting influences on gene expression

Background

Blood pressure (BP) has significant heritability, but the genes responsible remain largely unknown. Single nucleotide polymorphisms (SNPs) at the STK39 locus were recently associated with hypertension by genome-wide association in an Amish population; in vitro data from transient transfection experiments using reporter constructs suggested that altered STK39 expression might mediate the effect. However, other large studies have not implicated STK39 in hypertension. We determined whether reported SNPs influenced STK39 expression in vivo, or were associated with BP in a large British Caucasian cohort.

Methods

1372 members of 247 Caucasian families ascertained through a hypertensive proband were genotyped for reported risk variants in STK39 (rs6749447, rs3754777, rs35929607) using Sequenom technology. MERLIN software was used for family-based association testing. Cis-acting influences on expression were assessed in vivo using allelic expression ratios in cDNA from peripheral blood cells in 35 South African individuals heterozygous for a transcribed SNP in STK39 (rs1061471) and quantified by mass spectrometry (Sequenom).

Results

No significant association was seen between the SNPs tested and systolic or diastolic BP in clinic or ambulatory measurements (all p > 0.05). The tested SNPs were all associated with allelic expression differences in peripheral blood cells (p < 0.05), with the most significant association for the intronic SNP rs6749447 (P = 9.9 × 10^-4). In individuals who were heterozygous for this SNP, on average the G allele showed 13% overexpression compared to the T allele.

Conclusions

STK39 expression is modified by polymorphisms acting in cis and the typed SNPs are associated with allelic expression of this gene, but there is no evidence for an association with BP in a British Caucasian cohort.

Evaluating the causal relevance of diverse risk markers: horizontal systematic review

OBJECTIVES

To develop a new methodology to systematically compare evidence across diverse risk markers for coronary heart disease and to compare this evidence with guideline recommendations.

DESIGN

"Horizontal" systematic review incorporating different sources of evidence.

DATA SOURCES

Electronic search of Medline and hand search of guidelines. Study selection Two reviewers independently determined eligibility of studies across three sources of evidence (observational studies, genetic association studies, and randomised controlled trials) related to four risk markers: depression, exercise, C reactive protein, and type 2 diabetes. Data extraction For each risk marker, the largest meta-analyses of observational studies and genetic association studies, and meta-analyses or individual randomised controlled trials were analysed.

RESULTS

Meta-analyses of observational studies reported adjusted relative risks of coronary heart disease for depression of 1.9 (95% confidence interval 1.5 to 2.4), for top compared with bottom fourths of exercise 0.7 (0.5 to 1.0), for top compared with bottom thirds of C reactive protein 1.6 (1.5 to 1.7), and for diabetes in women 3.0 (2.4 to 3.7) and in men 2.0 (1.8 to 2.3). Prespecified study limitations were more common for depression and exercise. Meta-analyses of studies that allowed formal Mendelian randomisation were identified for C reactive protein (and did not support a causal effect), and were lacking for exercise, diabetes, and depression. Randomised controlled trials were not available for depression, exercise, or C reactive protein in relation to incidence of coronary heart disease, but trials in patients with diabetes showed some preventive effect of glucose control on risk of coronary heart disease. None of the four randomised controlled trials of treating depression in patients with coronary heart disease reduced the risk of further coronary events. Comparisons of this horizontal evidence review with two guidelines published in 2007 showed inconsistencies, with depression prioritised more in the guidelines than in our review.

CONCLUSIONS

This horizontal systematic review pinpoints deficiencies and strengths in the evidence for depression, exercise, C reactive protein, and diabetes as unconfounded and unbiased causes of coronary heart disease. This new method could be used to develop a field synopsis and prioritise future development of guidelines and research.

Familial and phenotypic associations of the aldosterone Renin ratio

CONTEXT

The aldosterone to renin ratio (ARR) is a marker of aldosterone excess, widely used to screen for primary aldosteronism (PA). The significance of a raised ARR in normotensive and hypertensive subjects and the phenotypic and familial factors affecting it are unclear.

OBJECTIVE

We estimated the distribution and heritability of the ARR and tested for associations between ARR and blood pressure (BP) with 11 polymorphisms at the CYP11B1/CYP11B2 locus.

DESIGN AND SETTING

A total of 1172 individuals from 248 Caucasian families ascertained via a hypertensive proband were evaluated.

MAIN OUTCOME MEASURE

Plasma aldosterone was measured by RIA, and plasma renin concentration was measured by the LIAISON Direct Renin chemiluminescent immunoassay.

RESULTS

Unadjusted and adjusted ARR were continuously distributed in normotensives and hypertensives, with no evidence of a cutoff that would identify a separate population with PA. Median ARR was 4.19 ng/liter per mIU/liter (range, 0.04-253.16). ARR levels were higher in females and associated with age, body mass index, and potassium. Antihypertensive agents had significant predictable effects on the ARR. Renin was negatively associated, and ARR was positively associated with ambulatory BP readings (P < 0.001) in subjects not taking antihypertensives. The heritability of the ARR was 38.1% (P < 10(-8)). Plasma aldosterone, but not ARR, was influenced by the intron 2 conversion variation in the CYP11B2 gene (beta = -0.07; P = 0.04).

CONCLUSIONS

The ARR is continuously distributed, is influenced by genetic and environmental factors, and is not a marker of a distinct pathological abnormality but possibly reflects the long-term influence of aldosterone on cardiovascular homeostasis.

Achieving the health Millennium Development Goals for South Africa: challenges and priorities

15 years after liberation from apartheid, South Africans are facing new challenges for which the highest calibre of leadership, vision, and commitment is needed. The effect of the unprecedented HIV/AIDS epidemic has been immense. Substantial increases in mortality and morbidity are threatening to overwhelm the health system and undermine the potential of South Africa to attain the Millennium Development Goals (MDGs). However The Lancet's Series on South Africa has identified several examples of leadership and innovation that point towards a different future scenario. We discuss the type of vision, leadership, and priority actions needed to achieve such a change. We still have time to change the health trajectory of the country, and even meet the MDGs. The South African Government, installed in April, 2009, has the mandate and potential to address the public health emergencies facing the country--will they do so or will another opportunity and many more lives be lost?

The burden of non-communicable diseases in South Africa

15 years after its first democratic election, South Africa is in the midst of a profound health transition that is characterised by a quadruple burden of communicable, non-communicable, perinatal and maternal, and injury-related disorders. Non-communicable diseases are emerging in both rural and urban areas, most prominently in poor people living in urban settings, and are resulting in increasing pressure on acute and chronic health-care services. Major factors include demographic change leading to a rise in the proportion of people older than 60 years, despite the negative effect of HIV/AIDS on life expectancy. The burden of these diseases will probably increase as the roll-out of antiretroviral therapy takes effect and reduces mortality from HIV/AIDS. The scale of the challenge posed by the combined and growing burden of HIV/AIDS and non-communicable diseases demands an extraordinary response that South Africa is well able to provide. Concerted action is needed to strengthen the district-based primary health-care system, to integrate the care of chronic diseases and management of risk factors, to develop a national surveillance system, and to apply interventions of proven cost-effectiveness in the primary and secondary prevention of such diseases within populations and health services. We urge the launching of a national initiative to establish sites of service excellence in urban and rural settings throughout South Africa to trial, assess, and implement integrated care interventions for chronic infectious and non-communicable diseases.

Clinical features, survival experience, and profile of plakophylin-2 gene mutations in participants of the arrhythmogenic right ventricular cardiomyopathy registry of South Africa

Little is known about arrhythmogenic right ventricular cardiomyopathy (ARVC) in Africa. The objective of this study was to delineate the clinical characteristics, survival, and genetics of ARVC in South Africa. Information on clinical presentation, electrocardiographic and cardiac imaging findings, histology, and outcome of cases with suspected ARVC was collected using the standardised form of the ARVC Registry of South Africa. Genomic DNA was screened for mutations in plakophylin-2 (PKP2) gene. Survival and its predictors were analyzed using the Kaplan-Meier and Cox proportional hazards regression methods, respectively. Fifty unrelated cases who met the diagnostic criteria for ARVC were enrolled between January 2004 and April 2009. Clinical presentation was similar to that reported in other studies. Annual mortality rate was 2.82%, five-year cumulative mortality rate 10%, and mean age at death 36.9 +/- 14.7 years. Overall survival was similar to the general South African population (P = 0.25). Independent risk factors for death were syncope (Hazard Ratio [HR] 10.73, 95% Confidence Interval [CI] 1.88-61.18, P = 0.008) and sustained ventricular tachycardia (HR = 22.97, 95%CI 2.33-226.18, P = 0.007). Seven PKP2 gene mutations were found in 9/36 (25%) unrelated participants, five being novel. The novel C1162T mutation occurred in four white South Africans sharing a common haplotype, suggesting a founder effect. Compound heterozygotes exhibited a severe phenotype signifying an allele dose effect. ARVC is associated with early mortality that is no different to the general South Africa population whose lifespan is shortened by HIV/AIDS. PKP2 gene mutations are common, have an allele dose effect, and a novel founder effect in white South Africans.