Genetic association study between T-786C NOS3 polymorphism and essential hypertension in an Algerian population of the Oran city

Genetic Polymorphisms of Endothelial Nitric Oxide Synthase Associated with Hypertension and Blood Homocysteine Levels

Purpose

Endothelial dysfunction is a key mechanism in the development of hypertension and is closely linked to impairment of endothelial nitric oxide synthase (eNOS) and hyperhomocysteinemia. Genetic polymorphisms of eNOS (rs1799983 and rs2070744) are strongly associated with the risk of hypertension in individuals of Asian ethnicities. This study aimed to investigate the relationship between these polymorphisms and the risk of hypertension associated with homocysteine levels.

Participants and Methods

For this cross-sectional study, we enrolled 370 Thai men aged 40-60 years from the Electricity Generating Authority of Thailand cohort study for both variants genotyping by TaqMan allelic discrimination analysis. Clinical, anthropometric, and biochemical parameters were also analyzed.

Results

In the high blood pressure group (n = 267), systolic and diastolic blood pressure and triglyceride levels were higher in those with homocysteine levels ≥ 15 µmol/L than in those with homocysteine levels < 15 µmol/L (p < 0.05). Significant risk of hypertension was found in GG and GT of rs1799983 (G894T), and in TT and TC of rs2070744 (T-786C), with higher ORs in heterozygous genotypes (all p values < 0.05). Further evaluation of the interactions between SNPs and HCY revealed that individuals with the GT or TC genotype, together with hyperhomocysteinemia, had an increased risk of hypertension (all p<0.05).

Conclusion

eNOS variants rs1799983 and rs2070744 may be risk factors for hypertension linked to hyperhomocysteinemia. These findings provide potentially useful healthcare strategies for the management of hypertension.

Pharmacogenomics of Hypertension in Africa: Paving the Way for a Pharmacogenetic-Based Approach for the Treatment of Hypertension in Africans

In Africa, the burden of hypertension has been rising at an alarming rate for the last two decades and is a major cause for cardiovascular disease (CVD) mortality and morbidity. Hypertension is characterised by elevated blood pressure (BP) ≥ 140/90 mmHg. Current hypertension guidelines recommend the use of antihypertensives belonging to the following classes: calcium channel blockers (CCB), angiotensin converting inhibitors (ACEI), angiotensin receptor blockers (ARB), diuretics, β-blockers, and mineralocorticoid receptor antagonists (MRAs), to manage hypertension. Still, a considerable number of hypertensives in Africa have their BP uncontrolled due to poor drug response and remain at the risk of CVD events. Genetic factors are a major contributing factor, accounting for 20% to 80% of individual variability in therapy and poor response. Poor response to antihypertensive drug therapy is characterised by elevated BPs and occurrence of adverse drug reactions (ADRs). As a result, there have been numerous studies which have examined the role of genetic variation and its influence on antihypertensive drug response. These studies are predominantly carried out in non-African populations, including Europeans and Asians, with few or no Africans participating. It is important to note that the greatest genetic diversity is observed in African populations as well as the highest prevalence of hypertension. As a result, this warrants a need to focus on how genetic variation affects response to therapeutic interventions used to manage hypertension in African populations. In this paper, we discuss the implications of genetic diversity in CYP11B2, GRK4, NEDD4L, NPPA, SCNN1B, UMOD, CYP411, WNK, CYP3A4/5, ACE, ADBR1/2, GNB3, NOS3, B2, BEST3, SLC25A31, LRRC15 genes, and chromosome 12q loci on hypertension susceptibility and response to antihypertensive therapy. We show that African populations are poorly explored genetically, and for the few characterised genes, they exhibit qualitative and quantitative differences in the profile of pharmacogene variants when compared to other ethnic groups. We conclude by proposing prioritization of pharmacogenetics research in Africa and possible adoption of pharmacogenetic-guided therapies for hypertension in African patients. Finally, we outline the implications, challenges, and opportunities these studies present for populations of non-European descent.

Endothelial nitric oxide synthase gene polymorphism (786T/C) in childhood acute lymphoblastic leukemia survivors

OBJECTIVES

To detect eNOS gene polymorphism and its relation to cardiovascular complications in pediatric acute lymphoblastic leukemia (ALL) survivors.

METHODS

CBC, renal and liver function tests, lipid profile, Carotid artery Intima Media Thickness (CIMT), and Brachial artery Intima Media Thickness (BIMT). eNOS gene polymorphism was done in 40 childhood ALL survivors and 40 controls.

RESULTS

There was no significant difference between survivors and control groups regarding 786 T/C polymorphism. There was a significant increase in serum cholesterol, TGs, LDL, VLDL, and HbA1c in the TC and CC group more than in the TT group, while there was a significant decrease in serum HDL in the TC and CC group more than in the TT group. There was no significant difference as regards echocardiography findings between different polymorphisms of 786 T/C, but there was a significant difference between 786 T/C groups with regard to the carotid and brachial arteries intima media thickness (IMT) measurements being significantly higher in the TC and CC group more than in the TT group.

CONCLUSION

Carotid and brachial arteries intima media thickness measurements were higher in the survivors when compared to healthy controls. eNOS gene polymorphism may play a role in modifying or developing CVD in pediatric ALL survivors.

Methylenetetrahydrofolate Reductase Polymorphism (rs1801133) and the Risk of Hypertension among African Populations: A Narrative Synthesis of Literature

In this review, we have gathered and analyzed the available genetic evidence on the association between the methylenetetrahydrofolate reductase gene (MTHFR), rs1801133 and the risk of Hypertension (HTN) in African populations, which was further compared to the global data evidence. This review was reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol and Human Genome Epidemiology Network (HuGENet) guidelines. Literature was retrieved through major search databases, including PubMed, Scopus, Web of Science, and African Journal Online. We identified 64 potential studies, of which 4 studies were from the African continent and 60 studies were reported globally. Among the studies conducted in Africa, only two (n = 2) reported a significant association between the MTHFR (rs1801133) and the risk of developing HTN. Only one (n = 1) study population was purely composed of black Africans, while others were of other ethnicities. Among studies conducted in other continents (n = 60), forty-seven (n = 47) studies reported a positive association between MTHFR (rs1801133) and the risk of developing HTN, whereas the remaining studies (n = 14) did not show a significant association. Available literature suggests an apparent association between rs1801133 and HTN in global regions; however, such information is still scarce in Africa, especially in the black African population.

Hypertension in African Populations: Review and Computational Insights

Hypertension (HTN) is a persistent public health problem affecting approximately 1.3 billion individuals globally. Treatment-resistant hypertension (TRH) is defined as high blood pressure (BP) in a hypertensive patient that remains above goal despite use of ≥3 antihypertensive agents of different classes including a diuretic. Despite a plethora of treatment options available, only 31.0% of individuals have their HTN controlled. Interindividual genetic variability to drug response might explain this disappointing outcome because of genetic polymorphisms. Additionally, the poor knowledge of pathophysiological mechanisms underlying hypertensive disease and the long-term interaction of antihypertensive drugs with blood pressure control mechanisms further aggravates the problem. Furthermore, in Africa, there is a paucity of pharmacogenomic data on the treatment of resistant hypertension. Therefore, identification of genetic signals having the potential to predict the response of a drug for a given individual in an African population has been the subject of intensive investigation. In this review, we aim to systematically extract and discuss African evidence on the genetic variation, and pharmacogenomics towards the treatment of HTN. Furthermore, in silico methods are utilized to elucidate biological processes that will aid in identifying novel drug targets for the treatment of resistant hypertension in an African population. To provide an expanded view of genetic variants associated with the development of HTN, this study was performed using publicly available databases such as PubMed, Scopus, Web of Science, African Journal Online, PharmGKB searching for relevant papers between 1984 and 2020. A total of 2784 articles were reviewed, and only 42 studies were included following the inclusion criteria. Twenty studies reported associations with HTN and genes such as AGT (rs699), ACE (rs1799752), NOS3 (rs1799983), MTHFR (rs1801133), AGTR1 (rs5186), while twenty-two studies did not show any association within the African population. Thereafter, an in silico predictive approach was utilized to identify several genes including CLCNKB, CYPB11B2, SH2B2, STK9, and TBX5 which may act as potential drug targets because they are involved in pathways known to influence blood pressure. Next, co-expressed genes were identified as they are controlled by the same transcriptional regulatory program and may potentially be more effective as multiple drug targets in the treatment regimens for HTN. Genes belonging to the co-expressed gene cluster, ACE, AGT, AGTR1, AGTR2, and NOS3 as well as CSK and ADRG1 showed enrichment of G-protein-coupled receptor activity, the classical targets of drug discovery, which mediate cellular signaling processes. The latter is of importance, as the targeting of co-regulatory gene clusters will allow for the development of more effective HTN drug targets that could decrease the prevalence of both controlled and TRH.

The incidence of NOS3 gene polymorphisms on newborns with large and small birth weight

The NOS3 gene polymorphisms T-786C, G894T and VNTR 4b/a are associated with a predisposition to the development of Metabolic Syndrome (MetS). The NOS3 gene contributes to a normal pregnancy and fetal development. According to their birthweight, newborns can be classified as: small (SGA), adequate (AGA) or large (LGA) for gestational age. The SGA and LGA present a higher risk of developing disorders related to MetS, both during childhood and adulthood. Therefore, the aim of this work is to relate the incidence of G894T, T-786C and VNTR 4b/a on SGA and LGA newborns and their mothers. 204 blood samples were collected from mothers (102) and the umbilical cords of 102 newborns (SGA = 12; AGA = 47; LGA = 43). The genotyping was performed through PCR-RFLP to evaluate presence of the G894T, T-786C and VNTR 4b/a polymorphisms. A significant difference was found between the groups of newborns in the genotypic frequency of T-786C, but without Hardy-Weinberg equilibrium. The VNTR 4b/a and the G894T polymorphisms showed no significance between the groups. The haplotype analysis showed that the SGA newborns presented the higher frequency of 4aGT (9.8%) and of the 4aTT combination (25.4%), while LGA newborns presented the higher frequency of the 4bTT haplotype (23%). Only the SGA newborns and their mothers presented the 4aTC haplotype. In conclusion, the NOS3 polymorphisms do not appear to be a factor to inadequate birth weight. However, the G894T and VNTR 4b/a polymorphisms, and the haplotype 4aTC, seem to influence the occurrence of SGA.