HYPOTHESIS: AN ANGIOTENSIN CONVERTING ENZYME/GENOTYPE, PRESENT IN ONE IN THREE CAUCASIANS, IS ASSOCIATED WITH AN INCREASED MORTALITY RATE

The 'Insertion/Deletion' Polymorphism, rs4340 and Diabetes Risk: A Pilot Study from a Hospital Cohort

The insertion/deletion, I/D polymorphism, in the gene encoding Angiotensin Converting Enzyme, ACE is a popular genetic marker for cardiovascular disease, CVD. With alarming rise in diabetes, the risk of CVD among Indian subjects is further enhanced. The present study explored the role of ACE I/D polymorphism, rs4340 as a genetic marker and its association with diabetes. Genomic DNA, isolated from a cohort of 410 urban subjects attending our hospital, was genotyped using polymerase chain reaction followed by electrophoresis. Among the subjects, 84 had type-2 diabetes and 68 had hypertension while 258 were free from these risk factors. Majority (57/84) of diabetic subjects were also suffering from hypertension. Genotype frequencies of ACE I/D polymorphism, of diabetic (84) patients were not different from that of non-diabetic subjects (258). In sharp contrast, we found significant differences, in genotype frequencies of women with diabetes (n = 38) compared to non-diabetic women (70). Diabetic women had significantly higher prevalence of the high risk 'D' allele. Analysis of odds ratio, OR revealed that women with 'D/D' genotype, exhibited threefold risk (OR 3.12, 95% CI 1.21-8.05; p = 0.018) of diabetes, in the recessive model (D/D vs I/I + I/D). Further when we analysed Odds ratio of diabetic women (8) who were free from hypertension, the results revealed even a greater, 6- fold (OR 6.0, 95% CI 1.29-27.96, p = 0.027) risk of diabetes for D/D homozygous women (D/D vs I/I + I/D). These results suggest 'sex-specific' association of ACE 'I/D' polymorphism, with type-2 diabetes, affecting women while there was no influence observed among men. In view of the increased cardiovascular mortality among Indians, data from our pilot study if confirmed in a larger cohort, could add value to our future intervention efforts.

Does Genetic Predisposition Contribute to the Exacerbation of COVID-19 Symptoms in Individuals with Comorbidities and Explain the Huge Mortality Disparity between the East and the West?

The elderly and patients with several comorbidities experience more severe cases of coronavirus disease 2019 (COVID-19) than healthy patients without underlying medical conditions. However, it is unclear why these people are prone to developing alveolar pneumonia, rapid exacerbations, and death. Therefore, we hypothesized that people with comorbidities may have a genetic predisposition that makes them more vulnerable to various factors; for example, they are likely to become more severely ill when infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To test this hypothesis, we searched the literature extensively. Polymorphisms of genes, such as those that encode angiotensin-converting enzyme 1 (ACE1), have been associated with numerous comorbidities, such as cardiovascular disease, hypertension, diabetes, chronic kidney disease, and obesity, and there are potential mechanisms to explain these associations (e.g., DD-type carriers have greater ACE1 activity, and patients with a genetic alpha-1 anti-trypsin (AAT) deficiency lack control over inflammatory mediators). Since comorbidities are associated with chronic inflammation and are closely related to the renin–angiotensin–aldosterone system (RAAS), these individuals may already have a mild ACE1/ACE2 imbalance before viral infection, which increases their risk for developing severe cases of COVID-19. However, there is still much debate about the association between ACE1 D/I polymorphism and comorbidities. The best explanation for this discrepancy could be that the D allele and DD subtypes are associated with comorbidities, but the DD genotype alone does not have an exceptionally large effect. This is also expected since the ACE1 D/I polymorphism is only an intron marker. We also discuss how polymorphisms of AAT and other genes are involved in comorbidities and the severity of SARS-CoV-2 infection. Presumably, a combination of multiple genes and non-genetic factors is involved in the establishment of comorbidities and aggravation of COVID-19.

Atherosclerotic and thrombotic genetic and environmental determinants in Egyptian coronary artery disease patients: a pilot study

BACKGROUND

Coronary artery disease (CAD) is the leading cause of morbidity and mortality worldwide. Multiple genetic variants in combination with various environmental risk factors have been implicated. This study aimed to investigate the association of twelve thrombotic and atherosclerotic gene variants in combination with other environmental risk factors with CAD risk in a preliminary sample of Egyptian CAD patients.

METHODS

Twenty three consecutive CAD patients undergoing diagnostic coronary angiography and 34 unrelated controls, have been enrolled in the study. Genotyping was based on polymerase chain reaction and reverse multiplex hybridization. Five genetic association models were tested. Data distribution and variance homogeneity have been checked by Shapiro-Wilk test and Levene test, respectively; then the appropriate comparison test was applied. Spearman's rank correlation coefficient was used for correlation analysis and logistic regression has been performed to adjust for significant risk factors. Clustering the study participants according to gene-gene and gene-environment interaction has been done by Detrended Correspondence Analysis (DCA).

RESULTS

The univariate analysis indicated that the five variants; rs1800595 (FVR2; factor 5), rs1801133 (MTHFR; 5,10-methylenetetrahydrofolate reductase), rs5918 (HPA-1; human platelet antigen 1), rs1799752 (ACE; angiotensin-converting enzyme), and rs7412 and rs429358 (ApoE; apolipoprotein E) were significantly associated with CAD susceptibility under different genetic models. Multivariate analysis revealed clustering of the study population into three patient groups (P) and one control group. FVR2 was the most variant associated with CAD patients, combined with the factor V Leiden (FVL) variant in P1 cluster and with both ACE and MTHFR 667C > T in P2. Whereas, P3 was mostly affected by both MTHFR 667C > T and FXIII (factor 13) V89L mutations. When combined with traditional risk factors, P1 was mostly affected by dyslipidemia, smoking and hypertension, while P2 was mostly affected by their fasting blood sugar levels and ApoE variant.

CONCLUSIONS

Taken together, these preliminary results could have predictive value to be applied in refining a risk profile for our CAD patients, in order to implement early preventive interventions including specific antithrombotic therapy. Further large scale and follow-up studies are highly recommended to confirm the study findings.

Polymorphism of ACE gene as the genetic predisposition of coronary artery disease in Eastern India

AIM

A case control study was designed to assess whether the prevalence of ACE gene polymorphism has any role in the development of CAD.

METHODS

The study included unrelated 217 cases with CAD and 255 healthy controls. PCR was done using primers followed by agarose gel electrophoresis for study of different ACE gene polymorphisms. Multiple logistic regression analysis was carried out to find association between studied genotypes and lifestyle as well as biochemical risk factors.

RESULTS

Both DD [OR: 2.16; 95%CI: (60.60-67.40)] and ID [OR: 1.48; 95%CI: (93.28-97.72)] genotypes of the ACE gene showed significant associations in the development of CAD. Coexistence of diabetes and hypertension found to be risk modifier of the disease. Tobacco intake in various forms elevates the risk of the disease among the cases with risk genotypes.

CONCLUSION

ID and DD genotypes of ACE gene came out to be predisposing factors for the CAD cases in our study population.

The relationship between ACE genotype and risk of severe hypoglycaemia in a large population-based cohort of children and adolescents with type 1 diabetes

AIMS/HYPOTHESIS

Genetic factors may account for familial clustering related to diabetes complications. Studies have shown a significant relationship between the presence of the deletion (D) allele of the gene encoding ACE and risk of severe hypoglycaemia. This large prospective cohort study assesses this relationship in a large sample of children and adolescents with type 1 diabetes.

SUBJECTS AND METHODS

We studied 585 children and adolescents (mean age 11.9 +/- 4 years, 48.4% males). The frequency of severe hypoglycaemia (an event leading to loss of consciousness or seizure) was prospectively assessed over the 13-year period 1992-2004. Patients were seen with their parents every 3 months and data recorded at each visit. The ACE gene was detected using PCR.

RESULTS

In our cohort of 585 children, 186 (31.8%) had at least one episode of severe hypoglycaemia, and of these 28.0% had the II genotype, 48.9% had the ID genotype and 23.1% had the DD genotype. This was in agreement with the Hardy-Weinberg proportion. A total of 477 severe hypoglycaemic episodes was recorded with a total of 3,404 person-years of follow-up, giving a total incidence of 14 per 100 patient-years. No significant increase in risk for DD genotype (incidence rate ratio = 0.97, 95% CI 0.61-1.55) relative to II genotype was observed.

CONCLUSIONS/INTERPRETATION

This large prospective study concludes that the presence of the D allele of the ACE gene does not predict a significantly higher risk of severe hypoglycaemia in type 1 diabetic children and adolescents.

Variations in angiotensin-converting enzyme gene insertion/deletion polymorphism in Indian populations of different ethnic origins

The pattern of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism in the Indian population is poorly known. In order to determine the status of the polymorphism, young unrelated male army recruits were screened. The population had cultural and linguistic differences and lived in an environment that varied significantly from one region to another. Analysis of the genotype, showed higher frequency of the insertion allele in four of the five groups i.e. I allele frequency was significantly higher (P < 0.05) in Dogras, Assamese and Kumaonese. The deletion allele frequency was comparatively higher in the fifth group that belonged to Punjab. A correlation was observed between the genotype and enzyme activity. Involvement of a single D allele in the genotype enhanced the activity up to 37.56 3.13%. The results suggested ethnic heterogeneity with a significant gene cline with higher insertion allele frequency. Such population-based data on various polymorphisms can ultimately be exploited in pharmacogenomics.