Interleukin-10 haplotypes are not associated with acute cerebral ischemia or high-risk transcranial Doppler in a newborn cohort of 395 children with sickle cell anemia

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.

Frequency of Cytokine Gene Polymorphism in Full-Term Newborns with Hypoxic Events

Background. An infant brain damage is an extremely urgent problem, this pathology is difficult to prevent, and subsequently it manifests itself with a variety of neurological consequences. Various mechanisms are involved in neurodamage; cytokines, as well as genes that control their activity, are under a great concern today. However, there is little data about their role as predictors of the brain damage among children after hypoxia. Aim of the research. To identify the frequency of cytokine gene polymorphism: interleukin (IL)-1β(C-511T), IL-1β(C3953T), IL-4(C589T), IL-6(C174G), IL-10(C819T), IL-10(G1082A) among newborns with hypoxic events. Materials and methods. The study involved 128 full-term newborn patients with hypoxic events: the first group (n = 48) included newborns who experienced chronic intrauterine hypoxia (CVH), the second group (n = 80) included newborns born in asphyxiation. Control group (52) included babies born without asphyxia and not suffering from CVH. A retrospective analysis of case-records was carried out. The material for molecular genetic analysis was DNA samples isolated from umbilical cord blood leukocytes using DNA Express Blood reagents (Scientific and Production Company LITECH, Moscow). Results. Compared to the control group (p = 0.03) children born in asphyxia had their T allele IL-1β (C-511T) prevailed. The group of newborn who had CVH had their TT genotype (p = 0.04) and the T IL-1β allele (C-511T) (p = 0.01) prevailed compared to the control group. In the same study group while studying the polymorphism of the IL-1β gene, the T allele (p = 0.03) at the point C3953T prevailed, in contrast to the control group. Conclusion. Due to the fact that cytokines are part of a reaction cascade leading to the secondary brain damage, under the action of hypoxia, it was found that among newborns undergoing asphyxia and chronic intrauterine hypoxia the increased frequencies of carriage of IL-1β-511TT and IL-1β-3953TT genotypes, and IL-1β-511T and IL-1β-3953T alleles increase the risk of neurodamage.

A meta-analysis on associations of IL-6 and IL-10 polymorphisms with susceptibility to ischemic stroke

BACKGROUND

Some previous studies already explored associations of interleukin-6 (IL-6) and interleukin-10 (IL-10) polymorphisms with ischemic stroke (IS). However, the results were conflicting. In this meta-analysis, we aimed to better analyze the relationship between IL-6/IL-10 polymorphisms and IS in a larger pooled population.

METHODS

We performed a systematic search of PubMed, Web of Science, Embase and CNKI. We calculated pooled odds ratios (ORs) and 95% confidence intervals (CIs) to estimate associations between IL-6/IL-10 polymorphisms and IS.

RESULTS

Totally 37 studies were included for analyses. A significant association with IS was observed for IL-10 rs1800896 polymorphism in AA versus GG + GA (recessive model, p = .001, OR = 1.42, 95%CI 1.15-1.75) in overall population. Further subgroup analyses showed that IL-6 rs1800795 was significantly associated with IS in Asians in GG versus GC + CC (dominant model, p = .0005, OR = 0.74, 95%CI 0.62-0.88), CC versus GG + GC (recessive model, p = .003, OR = 1.61, 95%CI 1.17-2.21) and G versus C (allele model, p = .01, OR = 0.74, 95%CI 0.58-0.93), whereas IL-10 rs1800896 polymorphism was significantly associated with cerebral infarction (CI) in GG versus GA + AA (dominant model, p = .02, OR = 2.04, 95%CI 1.14-3.64), GA versus GG + AA (overdominant model, p = .03, OR = 0.50, 95%CI 0.27-0.93) and G versus A (allele model, p = .01, OR = 1.92, 95%CI 1.16-3.17).

CONCLUSIONS

Our findings indicated that IL-6 rs1800795 polymorphism was significantly associated with individual susceptibility to IS in Asians, but not in Caucasians. In addition, IL-10 rs1800896 polymorphism was also significantly associated with individual susceptibility to IS, especially for CI.