Endothelial nitric oxide synthase gene polymorphisms and the risk of vasculopathy in sickle cell disease

Investigation of the relationships between eNOS T786C, G894T, intron 4 VNTR (4a/b) gene variations and prostate cancer development and progression

BACKGROUND

This study aimed to investigate the relationships between eNOS T786C, G894T, intron 4 VNTR (4a/b) gene variations and prostate cancer development and progression.

MATERIALS AND METHODS

This study included 88 patients diagnosed with prostate cancer and 91 healthy controls. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) methods were used to determine the genotype distributions of eNOS T786C, G894T, intron 4 VNTR (4a/b) gene variations.

RESULTS

In our study, the CC homozygous genotype of eNOS T786C gene variation was determined to be significantly higher in the prostate cancer patient group compared to the healthy control group (OR: 2.343, 95%Cl: 0.990-5.544, p = 0.026), while the CT heterozygous genotype was found to be significantly higher in the healthy control group compared to the prostate cancer patient group was found to be significantly higher (OR: 0.589, 95%Cl: 0.325-1.068, p = 0.041). In addition, while the TT homozygous genotype of the eNOS G894T gene variation was found to be significantly higher in the prostate cancer patient group compared to the healthy control group (OR: 9.068, 95%Cl: 4.396-18.777, p < 0.001), the GT heterozygous genotype was found to be significantly higher in the healthy control group compared to the prostate cancer patient group was determined significantly higher (OR: 0.227, 95%Cl: 0.121-0.427, p < 0.001). For eNOS (4VNTR (4a/b) - G894T) gene variations, aa-TT (p = 0.042) and bb-TT (p < 0.001) haplotype frequencies were significantly higher in the prostate cancer patient group, while aa-GT (p = 0.017), bb-GG (p = 0.049) and bb-GT (p < 0.001) haplotype frequencies were found to be significantly higher in the healthy control group. For eNOS (4VNTR (4a/b) - T786C) gene variations, the bb-CC haplotype frequency was determined to be significantly higher in the patient group (p = 0.049), while the bb-CT haplotype frequency was determined to be significantly higher in the control group (p = 0.008). For eNOS (T786C -G894T) gene variations, TT-TT (p < 0.001) and CC-TT (p = 0.025) haplotype frequencies were found to be significantly higher in the patient group. On the other hand, TT-GT (p = 0.002) and CT-GT (p < 0.001) haplotype frequencies were determined to be significantly higher in the control group. The aa genotype of the intron 4 VNTR (4a/b) gene variation was determined to be significantly higher at Gleason score ≥7 compared to Gleason score <7 (OR: 0.184, 95%Cl: 0.050-0.677, p = 0.005). PSA levels were determined significantly higher in patients with Gleason score 7 and above (p = 0.008). The risk of developing prostate cancer was found to be significantly higher in patients carrying the CC homozygous mutant genotype of the eNOS T786C gene variation (p = 0.024) and in patients carrying the TT homozygous genotype of the G894T gene variation (p = 0.021).

CONCLUSIONS

In our study, the CC homozygous genotype of the eNOS T786C gene variation was determined as a genetic risk factor for the development of prostate cancer, while the CT heterozygous genotype was determined as a protective factor against prostate cancer. For the eNOS G894T gene variation, the TT homozygous genotype was determined as a genetic risk factor for the development of prostate cancer, while the GT heterozygous genotype was determined as a protective factor against prostate cancer. Additionally, for eNOS (4VNTR (4a/b) - G894T) gene variations, aa-TT and bb-TT haplotypes have been identified as genetic risk factors for the development of prostate cancer, while aa-GT, bb-GG and bb-GT haplotypes have been identified as protective factors against the disease has been determined. For eNOS (4VNTR (4a/b) - T786C) gene variations, the bb-CC haplotype was determined as a genetic risk factor in the development of prostate cancer, while the bb-CT haplotype was determined as a protective factor against the disease. TT-TT and CC-TT haplotypes for eNOS (T786C -G894T) gene variations have been identified as genetic risk factors for the development of prostate cancer. In contrast, TT-GT and CT-GT haplotypes were found to be protective factors against the disease. The aa genotype of the intron 4 VNTR (4a/b) gene variation has also been identified as an important genetic risk factor in prostate cancer progression. Significantly increased PSA levels in patients with Gleason score 7 and above, and significantly increased PSA levels in patients carrying the CC and TT homozygous mutant genotype for T786C and G894T gene variations were determined as important risk factors. It is thought that the genetic biomarkers in our study may play a role as personalized therapeutic agents in slowing down the development of prostate cancer, increasing the effectiveness of treatment in prostate cancer, affecting the responses to drugs that regulate NO signaling, predetermining genetic predisposition to prostate cancer, and risk assessment in patients with prostate cancer.

Pulmonary Hypertension in Sickle Cell Disease: Novel Findings of Gene Polymorphisms Related to Pathophysiology

Pulmonary hypertension (PH) is a progressive and potentially fatal complication of sickle cell disease (SCD), affecting 6-10% of adult SCD patients. Various mechanisms and theories have been evaluated to explain the pathophysiology of this disease. However, questions remain, particularly regarding the clinical heterogeneity of the disease in terms of symptoms, complications, and survival. Beyond the classical mechanisms that have been thoroughly investigated and include hemolysis, nitric oxide availability, endothelial disorders, thrombosis, and left heart failure, attention is currently focused on the potential role of genes involved in such processes. Potential candidate genes are investigated through next-generation sequencing, with the transforming growth factor-beta (TGF-β) pathway being the initial target. This field of research may also provide novel targets for pharmacologic agents in the future, as is already the case with idiopathic PH. The collection and processing of data and samples from multiple centers can yield reliable results that will allow a better understanding of SCD-related PH as a part of the disease's clinical spectrum. This review attempts to capture the most recent findings of studies on gene polymorphisms that have been associated with PH in SCD patients.

Pharmacogenomics of Drugs Used in β-Thalassemia and Sickle-Cell Disease: From Basic Research to Clinical Applications

In this short review we have presented and discussed studies on pharmacogenomics (also termed pharmacogenetics) of the drugs employed in the treatment of β-thalassemia or Sickle-cell disease (SCD). This field of investigation is relevant, since it is expected to help clinicians select the appropriate drug and the correct dosage for each patient. We first discussed the search for DNA polymorphisms associated with a high expression of γ-globin genes and identified this using GWAS studies and CRISPR-based gene editing approaches. We then presented validated DNA polymorphisms associated with a high HbF production (including, but not limited to the HBG2 XmnI polymorphism and those related to the BCL11A, MYB, KLF-1, and LYAR genes). The expression of microRNAs involved in the regulation of γ-globin genes was also presented in the context of pharmacomiRNomics. Then, the pharmacogenomics of validated fetal hemoglobin inducers (hydroxyurea, butyrate and butyrate analogues, thalidomide, and sirolimus), of iron chelators, and of analgesics in the pain management of SCD patients were considered. Finally, we discuss current clinical trials, as well as international research networks focusing on clinical issues related to pharmacogenomics in hematological diseases.

Genetic Variation and Sickle Cell Disease Severity: A Systematic Review and Meta-Analysis

Importance

Sickle cell disease (SCD) is a monogenic disorder, yet clinical outcomes are influenced by additional genetic factors. Despite decades of research, the genetics of SCD remain poorly understood.

Objective

To assess all reported genetic modifiers of SCD, evaluate the design of associated studies, and provide guidelines for future analyses according to modern genetic study recommendations.

Data Sources

PubMed, Web of Science, and Scopus were searched through May 16, 2023, identifying 5290 publications.

Study Selection

At least 2 reviewers identified 571 original, peer-reviewed English-language publications reporting genetic modifiers of human SCD phenotypes, wherein the outcome was not treatment response, and the comparison was not between SCD subtypes or including healthy controls.

Data Extraction and Synthesis

Data relevant to all genetic modifiers of SCD were extracted, evaluated, and presented following STREGA and PRISMA guidelines. Weighted z score meta-analyses and pathway analyses were conducted.

Main Outcomes and Measures

Outcomes were aggregated into 25 categories, grouped as acute complications, chronic conditions, hematologic parameters or biomarkers, and general or mixed measures of SCD severity.

Results

The 571 included studies reported on 29 670 unique individuals (50% ≤ 18 years of age) from 43 countries. Of the 17 757 extracted results (4890 significant) in 1552 genes, 3675 results met the study criteria for meta-analysis: reported phenotype and genotype, association size and direction, variability measure, sample size, and statistical test. Only 173 results for 62 associations could be cross-study combined. The remaining associations could not be aggregated because they were only reported once or methods (eg, study design, reporting practice) and genotype or phenotype definitions were insufficiently harmonized. Gene variants regulating fetal hemoglobin and α-thalassemia (important markers for SCD severity) were frequently identified: 19 single-nucleotide variants in BCL11A, HBS1L-MYB, and HBG2 were significantly associated with fetal hemoglobin (absolute value of Z = 4.00 to 20.66; P = 8.63 × 10-95 to 6.19 × 10-5), and α-thalassemia deletions were significantly associated with increased hemoglobin level and reduced risk of albuminuria, abnormal transcranial Doppler velocity, and stroke (absolute value of Z = 3.43 to 5.16; P = 2.42 × 10-7 to 6.00 × 10-4). However, other associations remain unconfirmed. Pathway analyses of significant genes highlighted the importance of cellular adhesion, inflammation, oxidative and toxic stress, and blood vessel regulation in SCD (23 of the top 25 Gene Ontology pathways involve these processes) and suggested future research areas.

Conclusions and Relevance

The findings of this comprehensive systematic review and meta-analysis of all published genetic modifiers of SCD indicated that implementation of standardized phenotypes, statistical methods, and reporting practices should accelerate discovery and validation of genetic modifiers and development of clinically actionable genetic profiles.

Genetic modulation of anemia severity, hemolysis level, and hospitalization rate in Angolan children with Sickle Cell Anemia

BACKGROUND

Sickle Cell Anemia (SCA) is a genetic disease caused by the c.20 A > T mutation in HBB gene, generally characterized by sickle erythrocytes, chronic hemolytic anemia, and vaso-occlusive events. This study aimed to investigate genetic modulators of anemia severity, chronic hemolytic rate, and clinical manifestations in pediatric SCA patients from Angola, where the disease is a severe public health problem.

METHODS AND RESULTS

The study was conducted on 200 SCA children living in Luanda or Caxito province. Their clinical phenotype was collected from patients' hospital records. Hematological and biochemical phenotypes were characterized in steady state condition. Twelve polymorphic regions in VCAM1, CD36 and NOS3 genes were genotyped using PCR, RFLP, and Sanger sequencing. CD36 gene promoter variants showed a significant impact on anemia severity. Particularly, the rs1413661_C allele was associated with lower hemoglobin levels, and increased number of hospitalizations and transfusions. This is the first report associating this SNP with SCA phenotypic heterogeneity. Moreover, the rs1041163_C allele in VCAM1 was associated with lower LDH levels; inversely the rs2070744_C allele in NOS3 was related with higher LDH levels and number of hospitalizations, being a risk factor for increased hemolytic rate.

CONCLUSION

This study highlights, for the first time in the Angolan population, the importance of the genetic modifiers of vascular cell adhesion and nitric oxide metabolism in SCA pediatric phenotypic variability.

Genetic Analysis of Patients With Sickle Cell Anemia and Stroke Before 4 Years of Age Suggest an Important Role for Apoliprotein E

BACKGROUND

Ischemic stroke is a devastating complication affecting children with sickle cell anemia. Genetic factors are likely to be important in determining the risk of stroke but are poorly defined.

METHODS

We have studied a cohort of 19 children who had an overt ischemic stroke before 4 years of age. We predicted genetic determinants of stroke would be more prominent in this group. We performed whole exome sequencing on this cohort and applied 2 hypotheses to our variant filtering. First, we looked for strong, potentially mono- or oligogenic variants for ischemic stroke, and second, we considered that more common polygenic variants will be enriched in our cohort. Candidate variants emerging from both strategies were validated in a cohort of 283 patients with sickle cell anemia and known pediatric cerebrovascular outcomes. We used principal component analysis in this cohort to control for relatedness and population substructure.

RESULTS

Our primary finding was that the Apoliprotein E genotypes ε2/ε4 and ε4/ ε4, defined by the interplay of rs7412 and rs429358, were associated with increased stroke risk, with an odds ratio of 4.35 ([95% CI, 1.85-10.0] P=0.0011) for ischemic stroke in the validation cohort. We also found that rs2297518 in NOS (NO synthase) 2 (odds ratio, 2.25 [95% CI, 1.21-4.19]; P=0.014) and rs2230123 in signal transducer and activator of transcription (odds ratio, 2.60 [95% CI, 1.30-5.20]; P=0.009) both had increased odds ratios for ischemic stroke, although these two variants were below the threshold for statistical significance after correction for multiple testing.

CONCLUSIONS

These data identify new loci for future functional investigations into cerebrovascular disease in sickle cell anemia. Based on African population reference allele frequencies, the Apoliprotein E genotypes would be present in about 10% of children with sickle cell anemia and represent a genetic risk factor that is potentially modifiable by both dietary and pharmaceutical manipulation of its dyslipidemic effects.

Managing patients with sickle cell disease in primary care

Sickle cell disease (SCD) is a group of disorders affecting the hemoglobin in erythrocytes. SCD is associated with significant morbidity and mortality and occurs most commonly among people of African ancestry. In 2014, the National Heart, Lung, and Blood Institute updated its guidelines for the management of SCD. These guidelines were implemented to provide evidence-based recommendations to assist primary care clinicians in the proper management of patients with SCD. This article reviews the current practice guidelines for SCD, with attention to health maintenance and hydroxyurea.

Genetic modifiers of severity in sickle cell disease

Sickle cell disease (SCD) is one of the most common single disease disorders world-wide. It is remarkable for its clinical heterogeneity, even among individuals with identical genotypes. Some individuals experience morbidity and mortality in early childhood, while others have a relatively mild course, and normal or near normal life expectancy. Many clinical complications are associated with SCD; most notably frequent pain episodes, stroke, acute chest syndrome, avascular necrosis, nephropathy, retinopathy and pulmonary hypertension. While the effects of higher fetal hemoglobin (HbF) levels, UGTA1A polymorphisms, alpha-thalassemia and G6PD deficiency on SCD has been extensively studied, these variables do not explain all of the clinical heterogeneity of SCD. It is not known why some patients develop certain complications, and it is difficult to predict which complications a particular patient will experience. Much work has been done to identify genetic variants associated with these disease complications; many associations remain unvalidated. As the field continues to move beyond small sample collections and candidate gene approaches into whole genome sequencing and merging of samples from all over the world, we will identify more genetic variants associated with development of specific SCD related complications, and hopefully leverage this knowledge into targeted therapies.

Pharmacogenomics of sickle cell disease: steps toward personalized medicine

Sickle cell disease (SCD) is a monogenetic disease but has a wide range of phenotypic expressions. Some of these differences in phenotype can be explained by genetic polymorphisms in the human globin gene. These polymorphisms can result in different responses to typical treatment, sometimes leading to inadequate therapeutics. Research is revealing more polymorphisms, and therefore, new targets for intervention to improve outcomes in SCD. This area of pharmacogenomics is continuing to develop. We provide a brief review of the current literature on pharmacogenomics in SCD and possible targets for intervention.