Synergistic Protective Effect of Sickle Cell Trait and Blood Group-O on the Risk of Endemic Burkitt's Lymphoma.

BACKGROUND: Previous research strongly suggest that malaria is an important factor in the pathogenesis of endemic Burkitt's lymphoma (eBL). Therefore, genetic factors such as sickle cell trait (SCT) and blood group-O that offer protection against severe malaria would be expected to reduce the risks of eBL. However, previous reports on the protective roles of SCT and blood group-O against the risks of eBL were inconclusive. Hence, the need for further studies on the protective roles of SCT and blood group-O separately, and also to investigate whether or not the combined anti-severe malaria protective roles of SCT and blood group-O have synergistic effects in reducing the risks of eBL. We therefore hypothesize that SCT and blood group-O are independently associated with reduced risks of eBL, and the co-inheritance of both factors (SCT and group-O) would provide greater protection against eBL. If our hypothesis is correct, children who inherited both SCT and blood group-O would have lower risks of eBL than their counterparts who inherited SCT or blood group-O separately. To the best of our knowledge, the possible synergistic relationship between SCT and blood group-O with regards to the risk of eBL has not been previously studied. PATIENTS AND METHODS: We conducted a retrospective logistic regression analysis of the frequencies of Hb phenotypes and ABO blood groups among patients with eBL in order to determine the separate and synergistic protective effects of SCT and blood group-O on the risk of eBL in Nigeria where eBL is among the most common malignant childhood cancers. RESULTS: The Odd Ratios (OR) for the risk of eBL were 0.52 for 'SCT irrespective of ABO blood group'; 0.49 for 'blood group-O irrespective of Hb phenotype'; and 0.23 for 'SCT with blood group-O'. DISCUSSION: These values suggest that both SCT and blood group-O are independently associated with modest reduction in the risk of eBL. However, when SCT with blood group-O was assessed for the risk factor for eBL, we obtained an Odds ratio of 0.23, which was significantly lower than the OR values for SCT (0.52) and blood group-O (0.49) separately. These figures suggest that coinheritance of SCT and blood group-O offers greater reduction in the risk of eBL than that provided by either SCT or blood group-O separately. The greater protection against eBL provided by the coinheritance of SCT and blood group-O is interpreted to be the resultant synergistic effect of the combined anti-malarial attributes of SCT and blood group-O. CONCLUSION: These findings suggest that the combined anti-malarial protective roles of SCT and blood group-O have synergistic effects in reducing the risks of eBL. This study has provided further evidence on the association between malaria-protective genetic polymorphisms and eBL, which is consistent with the aetiologic role of malaria in the pathogenesis of the tumour. Hence, the need for malaria endemic countries to intensify malaria control programs in order to curtail the incidence of eBL.

Prevalence of antibody to hepatitis B core antigen among hepatitis B surface antigen-negative blood donors in Ilorin, Nigeria: A cross-sectional study.

BACKGROUND: Post-transfusion hepatitis occurs even with stringent donor selection criteria and screening for hepatitis B surface antigen (HBsAg). The objective of this study was to determine the prevalence of antibody to hepatitis B core antigen (anti-HBc) in HBsAg-negative blood donors. METHODS: This was a cross-sectional study in which 200 HBsAg-negative blood donors were recruited. Screening for viral markers was done using both a rapid test kit and enzyme-linked immunosorbent assay (ELISA) for anti-HBc IgM. Quantitative and qualitative analysis of anti-HBc IgM was done by "capture" enzyme immunoassay using DIA.PRO HBc IgM test kits. The other viral markers were investigated using one step cassette style HBV tests. SPSS version 16 was used for data analysis. A P-value of 0.05 or less was considered significant. RESULTS: There were 190 male (95%) and 10 female (5%) blood donors, with a mean age of 31.7 ± 7.9 years. The prevalence of anti-HBc IgM was 4%. The other viral markers (HBeAg, anti-HBeAg, anti-HBs and total anti-HBc) had a prevalence of 1.5%, 23%, 2.5%, and 32.5%, respectively. CONCLUSIONS: The prevalence of anti-HBc IgM in this study was high, and this supports the fact that screening blood donors for HBsAg alone is not sufficient to prevent transmission of HBV.

Impact of sickle cell trait on the thrombotic risk associated with non-O blood groups in northern Nigeria.

BACKGROUND: The non-O blood group is an established risk factor for deep vein thrombosis (DVT), while controversy surrounds the role of sickle cell trait (SCT) as a risk factor for DVT. We hypothesised that if SCT is a risk factor for DVT, individuals with non-O blood groups and SCT (Hb AS) would have a higher risk of DVT than their counterparts with non-O blood groups and normal haemoglobin phenotype (Hb AA). MATERIALS AND METHODS: We retrospectively analysed the prevalence of SCT and non-O blood groups among 148 DVT patients with control subjects in order to determine the role of SCT as a risk factor for DVT and its impact on the risk of DVT among patients with non-O blood groups. RESULTS: In comparison with control subjects, DVT patients had significantly higher prevalences of SCT (35.1% vs 27.7%, p=0.04) and non-O blood groups (68.9% vs 45.9%, p=0.02). The odds ratios for DVT due to SCT, non-O blood groups with normal Hb phenotype (Hb AA) and non-O blood groups with SCT (Hb AS) were 1.3, 2.4 and 3.5, respectively. DISCUSSION: These results suggest that SCT by itself is a weak risk factor for DVT but it has the potential of escalating the DVT risk among patients with non-O blood groups. The combined effects of elevated clotting factors (non-O group effect) and increased clotting factor activation (SCT effect) were responsible for the escalated DVT risk among patients with co-inheritance of non-O blood groups and SCT. Co-inheritance of SCT and non-O blood group is, therefore, an important mixed risk factor for DVT. This should be taken into account when assessing DVT risk profiles of patients in Africa and other parts of the world where the SCT is prevalent.