Correlation of angiotensin I-converting enzyme gene insertion/deletion polymorphism with rheumatic heart disease: a meta-analysis

The Impact of ACE Gene Variants on Acute-Phase Reactants in Children with Rheumatic Heart Disease

Rheumatic heart disease (RHD) is the most important sequela of upper respiratory group A Streptococcus (GAS) infection. The role of the common angiotensin-converting enzyme (ACE) insertion/deletion (I/D) variant in the disease and its subtypes remains uncertain. The acute-phase reactants (APRs) C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) form part of the Jones criteria for diagnosing RHD, and genetic factors are known to influence baseline CRP and ESR levels. Therefore, here, we investigated the relationship between the ACE I/D polymorphism and APR levels in RHD. A total of 268 individuals were recruited, including 123 RHD patients and 198 healthy controls. There was a trend toward a higher D allele frequency in RHD patients. The ACE I/D polymorphism genotype frequency and DD+ID allelic carriage were significantly associated with a high APR level (p = 0.04 and p = 0.02, respectively). These results highlight the importance of ACE I/D polymorphisms in RHD for disease stratification, but not for disease predisposition. Further studies in larger cohorts and different populations are now required to confirm this association and to explore the mechanism of this effect.

The Genetic Control of the Rheumatic Heart: Closing the Genotype-Phenotype Gap

Rheumatic heart disease (RHD) is a heritable inflammatory condition characterized by carditis, arthritis, and systemic disease. Although remaining neglected, the last 3 years has seen some promising advances in RHD research. Whilst it is clear that RHD can be triggered by recurrent group A streptococcal infections, the mechanisms driving clinical progression are still poorly understood. This review summarizes our current understanding of the genetics implicated in this process and the genetic determinants that predispose some people to RHD. The evidence demonstrating the importance of individual cell types and cellular states in delineating causal genetic variants is discussed, highlighting phenotype/genotype correlations where possible. Genetic fine mapping and functional studies in extreme phenotypes, together with large-scale omics studies including genomics, transcriptomics, epigenomics, and metabolomics, are expected to provide new information not only on RHD but also on the mechanisms of other autoimmune diseases and facilitate future clinical translation.

I/D Polymorphism Gene ACE and Risk of Preeclampsia in Women with Gestational Diabetes Mellitus

Preeclampsia (PE) and gestational diabetes mellitus (GDM) are the most common complications of pregnancy, which result in adverse outcomes for the mother and the fetus. GDM is regarded as a separate independent risk factor for PE development, as evidenced by a higher preeclampsia rate in gestational diabetes mellitus than in the general population. The role the endothelial cell dysfunction plays is considered to be the most reasonable one in the origin of these diseases. The activity of plasma and tissue angiotensin converting enzyme (ACE) is believed to be genetically controlled. The available data suggests that increased ACE activity due to deletion (D)/insertion (I) in the 16th intron of ACE gene, which is called ACE gene I/D polymorphism, is associated with preeclampsia and varies depending on the studied population and the geography. We did not find any literature data that estimates the influence of ACE gene I/D polymorphism on PE rate in pregnant women with GDM. Therefore, the present study aimed to investigate a relationship between ACE gene I/D polymorphism and preeclampsia development in the case of GDM in the Russian population. The study used the genomic DNA derived by phenol-chloroform extraction method from venous blood samples in 137 pregnant women, including samples of 74 women with GDM accompanied with PE and the blood samples of 63 women with GDM w/o preeclampsia. Genotyping of insertion/deletion in the I/D region (16 intron of АСЕ gene) was conducted by real-time PCR using the TaqMan competing probe technology. The particular features in the frequency array of alleles and genotypes of the ACE gen I/D polymorphism under review, as associated with preeclampsia development risk in pregnant women with GDM, were identified. The acquired data testify to the need to further study of ACE gene I/D region polymorphism association in a large patient sample taking into account the PE and GDM risk factors estimated in the clinical practice.

Genetic variants in rheumatic fever and rheumatic heart disease

Genetic association studies in rheumatic heart disease (RHD) have the potential to contribute toward our understanding of the pathogenetic mechanism, and may shed light on controversies about RHD etiology. Furthermore, genetic association studies may uncover biomarkers that can be used to identify susceptible individuals, and contribute toward developing vaccine and novel therapeutic targets. Genetic predisposition to rheumatic fever and RHD has been hypothesized by findings from familial studies and observed associations between genes located in the human leukocyte antigens on chromosome 6p21.3 and elsewhere in the genome. We sought to summarize, from published Genetic association studies in RHD, evidence on genetic variants implicated in RHD susceptibility. Using HuGENet™ systematic review methods, we evaluated 66 studies reporting on 42 genes. Existing meta-analyses of candidate gene studies suggest that TGF-β1 [rs1800469], and IL-1β [rs2853550] single nucleotide polymorphisms (SNPs) contribute to susceptibility to RHD, whereas the TNF-α [rs1800629 and rs361525], TGF-β1 [rs1800470 and rs4803457], IL-6 [rs1800795], IL-10 [rs1800896] were not associated with RHD. However, candidate gene studies in RF/RHD are relatively small, thus lacking statistical power to identify reliable and reproducible findings, emphasizing the need for large-scale multicenter studies with different populations.

Towards developing a vaccine for rheumatic heart disease

Rheumatic heart disease (RHD) is the most serious manifestations of rheumatic fever, which is caused by group A Streptococcus (GAS or Streptococcus pyogenes) infection. RHD is an auto immune sequelae of GAS pharyngitis, rather than the direct bacterial infection of the heart, which leads to chronic heart valve damage. Although antibiotics like penicillin are effective against GAS infection, improper medical care such as poor patient compliance, overcrowding, poverty, and repeated exposure to GAS, leads to acute rheumatic fever and RHD. Thus, efforts have been put forth towards developing a vaccine. However, a potential global vaccine is yet to be identified due to the widespread diversity of S. pyogenes strains and cross reactivity of streptococcal proteins with host tissues. In this review, we discuss the available vaccine targets of S. pyogenes and the significance of in silico approaches in designing a vaccine for RHD.