Influence of Amerindian mitochondrial DNA haplogroups on thrombosis susceptibility and frequency of four genetic prothrombotic variants in Southern Chilean subjects

Association of β-fibrinogen polymorphisms and venous thromboembolism risk: A PRISMA-compliant meta-analysis

BACKGROUND

Venous thromboembolism (VTE) is a multifactorial disease in which genetic and acquired risk factors may contribute to disease pathogenesis. Several studies have demonstrated that β-fibrinogen (FGB) polymorphisms are associated with the risk of VTE. However, the results of these studies were not totally consistent. In this paper, we performed a meta-analysis to further investigate the relationship between FGB polymorphisms and susceptibility to VTE.

METHODS

To identify studies pertinent to the focused question, the following databases were systematically searched: PubMed, EMBASE, Web of Science, China National Knowledge Infrastructure, and Wanfang Data. The strength of correlations was evaluated by calculating pooled odds ratios (ORs) and 95% confidence intervals (95% CIs). Subgroup analyses stratified by ethnicity, type of disorders, and source of control were also performed.

RESULTS

Overall, A total of 18 relevant case-control studies met the inclusion criteria and were incorporated in this meta-analysis, involving 3033 VTE cases and 4547 healthy controls. FGB -455G>A polymorphism and -148C>T polymorphism were not significantly associated with susceptibility to VTE in overall populations. However, results of stratified analysis demonstrated that among Caucasian population, the -455G>A mutation was negatively associated with the risk of VTE under all genetic comparison models (A:G OR = 0.80 95% CI = 0.70-0.91; GA + AA:GG OR = 0.80 95% CI = 0.68-0.93; GA:GG OR = 0.84 95% CI = 0.71-0.98; AA:GG + GA OR = 0.61 95% CI = 0.43-0.87; AA:GG OR = 0.57 95% CI = 0.40-0.82), which indicates FGB -455G>A polymorphism may be a protective factor for VTE. There was no correlation between -148C>T polymorphism and susceptibility to VTE in all subgroup analyses.

CONCLUSION

FGB -455G>A polymorphism was associated with a decreased risk of VTE among the Caucasian population.

Genetic risk factors in patients with deep venous thrombosis, a retrospective case control study on Iranian population

Background

Venous thromboembolism (VTE) could be manifested as deep venous thrombosis (DVT) or pulmonary embolism (PE). DVT is usually the more common manifestation and is usually formation of a thrombus in the deep veins of lower extremities. DVT could occur without known underlying cause (idiopathic thrombosis) which could be a consequence of an inherited underlying risk factor or could be a consequence of provoking events, such as trauma, surgery or acute illness (provoked thrombosis). Our aim in this study was to assess the impact of some previously reported genetic risk factors including, methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C, plasminogen activator inhibitor-1(PAI-1) 4G/5G, prothrombin 20210 and FV Leiden on occurrence of DVT in a population of Iranian patients.

Methods

This long-term study was conducted on 182 patients with DVT and also 250 age and sex matched healthy subjects as control group. The diagnosis of DVT was based on patient’s history, clinical findings, D-dimer test, and confirmed by Doppler ultrasonography. After confirmation of DVT, both groups were assessed for the five mentioned mutations. The relationship between mutations and predisposition to DVT was calculated by using logistic regression and expressed as an OR with a 95 % confidence interval (CI).

Results

Our results revealed that FV Leiden (OR 6.7; 95 % CI = 2.2 to 20.3; P = 0.001), MTHFR C677T (OR 6.0; 95 % CI = 2.2 to 16.4; P < 0.001), MTHFR A1298C (OR 8.3; 95 % CI = 4.4 to 15.8; P < 0.001), and PAI-1 4G/5G (OR 3.8; 95 % CI = 2.1 to 7.2; P < 0.001) mutations were all significantly associated with an increased risk of DVT. Prothrombin 20210 was found in none of the patients and controls.

Conclusion

Our findings suggest that genetic risk factors have a contributory role on occurrence of DVT.

The influence of ethnicity on warfarin dosage requirements in the chilean population

Background

Vitamin K antagonists are drugs that are widely prescribed around the world and their use has helped improve the prognosis of patients with thromboembolic disease. However, a high interindividual variability has been observed in dosage requirements to reach the desired anticoagulation range that could be due to environmental and genetic factors. Studies suggest that ethnicity influences coumarin response, supporting the observed differences in dose requirements across various populations. Studies using mitochondrial DNA (mtDNA) markers have suggested that the Chilean population has a predominantly Amerindian genetic pool.

Objective

To evaluate the influence of ethnicity, defined by the presence of Amerindian mtDNA haplogroups, on the variability in therapeutic response to warfarin in the Chilean population.

Methods

A total of 191 patients treated with warfarin were included in this study. Analysis of the mitochondrial genome for detecting the presence of Amerindian mtDNA haplogroups was performed using polymerase chain reaction and polymerase chain reaction restriction fragment length polymorphism techniques. The evaluation of warfarin requirements according to each haplogroup was performed by ANOVA with a 95% CI and assuming statistical significance at P < 0.05.

Results

Based on the presence of an mtDNA haplogroup, 91% of the Chilean population had an Amerindian background. There were no significant differences in warfarin dosage requirements among the different Amerindian haplogroups (P = 0.083).

Conclusions

The presence of Amerindian mtDNA haplogroup does not influence warfarin dosage requirements in the Chilean population.

FTO gene is related to obesity in Chilean Amerindian children and impairs HOMA-IR in prepubertal girls

OBJECTIVE

The objective of this study was to investigate the allelic frequency of the fat mass and obesity-associated (FTO) gene (rs9939609) and its influences on obesity and metabolic risk biomarkers in a cohort of normal weight and obese Chilean children determining its ethnicity.

METHODS

A total of 136 normal weight children and 238 obese children (between 6 and 11 yr old) from an urban setting were recruited for this case-control study. The children were classified as normal weight [body mass index (BMI) ≥ 5th and < 85th percentiles] or obese (BMI >95th percentile), according to the international age- and gender-specific percentiles defined by the Center for Disease Control and Prevention. The analysis of serum markers was carried out using commercial kits. The FTO polymorphism was determined through a high-resolution melting enabled real time polymerase chain reaction. Ethnicity was determined by analyzing mitochondrial DNA by the restriction fragment length polymorphism method.

RESULTS

As much as 85% of the cohort was Amerindian. The minor A allele of rs9939609 was associated with obesity (odds ratio (OR): 1.422 [95% confidence interval (CI) 1.068-1.868] p = 0.015), calculated using an additive model. In sex-stratified analysis we found that the risk variant (A) of rs9939609 was associated with a higher homeostasis model of assessment for insulin (HOMA-IR) in prepubertal obese girls. In male carriers of the A allele, HOMA-IR showed no further deterioration than that already associated with obesity.

CONCLUSIONS

In summary, we confirm the association of the FTO gene single-nucleotide polymorphism rs9939609 with obesity in Chilean Amerindian children. Furthermore we show an association between the risk allele (A) and insulin resistance-related markers in prepubertal obese girls.