Haptoglobin Gene Polymorphism among Sickle Cell Patients in West Cameroon: Hematological and Clinical Implications

Haptoglobin is a protein involved in protecting the body from the harmful effects of free hemoglobin. The haptoglobin gene exhibits a polymorphism, and the different genotypes do not have the same capacity to combat the free hemoglobin effects. The present study aimed at determining the polymorphic distribution of haptoglobin in sickle cell patients (SCPs) from West Cameroon and their impact on the hematological parameters, as well as clinical manifestations of the disease severity. Haptoglobin genotype of 102 SCPs (SS) and 115 healthy individuals (60 AA and 55 AS) was determined by allele-specific polymerase chain reaction, and the complete blood count was determined using the AutoAnalyser. Results showed that the genotype Hp2-2 was significantly ( p < 0.05) represented in SS patients (54%) than in controls AA and AS (27% and 29%, respectively), while Hp2-1 was mostly found ( p < 0.05) in AS (42%) and AA (38%), against 15% in SS. The allelic distribution in SS patients was Hp2: 0.613, Hp1S: 0.304, and Hp1F: 0.084. In AA and AS controls, the proportions of the Hp1 and Hp2 alleles were similar (around 0.5 each), with 0.282 for Hp1S and 0.218 for Hp1F in AS and 0.283 for Hp1S and 0.258 for Hp1F in AA. The distribution of the haptoglobin genotypes did not reveal any significant difference across hematological parameters and clinical manifestations of disease severity in SCP and controls. SCP with Hp1S-1F genotype presented the highest level of hemoglobin. Although Hp2-2 was more frequent in SS patients, it appeared not to be related to the hematological parameters and to the disease’s severity. Further investigations are necessary to explore the impact of Hp polymorphism such as antioxidant, lipid profile, and functionality of some tissues in SCP in Cameroon.

Effect of Anacetrapib on Cholesterol Efflux Capacity: A Substudy of the DEFINE Trial

Background Anacetrapib is the only cholesteryl ester transfer protein inhibitor proven to reduce coronary heart disease (CHD). However, its effects on reverse cholesterol transport have not been fully elucidated. Macrophage cholesterol efflux (CEC), the initial step of reverse cholesterol transport, is inversely associated with CHD and may be affected by sex as well as haptoglobin copy number variants among patients with diabetes mellitus. We investigated the effect of anacetrapib on CEC and whether this effect is modified by sex, diabetes mellitus, and haptoglobin polymorphism. Methods and Results A total of 574 participants with CHD were included from the DEFINE (Determining the Efficacy and Tolerability of CETP Inhibition With Anacetrapib) trial. CEC was measured at baseline and 24‐week follow‐up using J774 macrophages, boron dipyrromethene difluoride–labeled cholesterol, and apolipoprotein B–depleted plasma. Haptoglobin copy number variant was determined using an ELISA assay. Anacetrapib increased CEC, adjusted for baseline CEC, risk factors, and changes in lipids/apolipoproteins (standard β, 0.23; 95% CI, 0.05–0.41). This CEC‐raising effect was seen only in men ( P interaction=0.002); no effect modification was seen by diabetes mellitus status. Among patients with diabetes mellitus, anacetrapib increased CEC in those with the normal 1‐1 haptoglobin genotype (standard β, 0.42; 95% CI, 0.16–0.69) but not the dysfunctional 2‐1/2‐2 genotypes ( P interaction=0.02). Conclusions Among patients with CHD, anacetrapib at a dose linked to improved CHD outcomes significantly increased CEC independent of changes in high‐density lipoprotein cholesterol or other lipids, with effect modification by sex and a novel pharmacogenomic interaction by haptoglobin genotype, suggesting a putative mechanism for reduced risk requiring validation.

Haptoglobin Genotype Affects Inflammation after Aneurysmal Subarachnoid Hemorrhage

Background: Haptoglobin (Hp) binds to and facilitates clearance of heme. Compared with HP 1-1 and 1-2 genotypes, HP 2-2 has a weaker binding affinity and has been linked with increased inflammation and vasospasm after aneurysmal subarachnoid hemorrhage (SAH). Objective: To assess levels of inflammatory cytokines in the context of different HP genotypes. Methods: Patients were enrolled among those presenting with spontaneous aneurysmal SAH. Blood was drawn at four time points; <24 hours (T1), 24-48 hours (T2), 3-5 days (T3), and 6-8 days (T4). Blood was analyzed for levels of 41 cytokines at each time point, as well as for HP genotypes. These data were analyzed using mixed-effect models to assess the association between HP genotypes and cytokine levels. The modified Rankin Scale (mRS) score was obtained at discharge, 3 months, and 6 months. Results: Fifty-seven patients were enrolled. Compared with HP 1-1 and 1-2, subjects encoding HP 2-2 had elevated levels of the following cytokines at all time points: FLT3L, IFNγ, IL-17A, TGFα, and VEGF-A. Elevations were also seen at some time points for IL-8, CSF2, FGF2, IL-7, IL-12p70, and TNFα. This study was not powered to detect differences in functional outcome; however, there were no significant differences in dichotomized mRS score between patients with HP 1- 1/1-2 or HP 2-2. Conclusion: Our findings indicate that HP 2-2 genotype leads to increased proinflammatory cytokine levels compared with HP 1-1/1-2 genotypes. These data may provide guidance for further studies seeking to identify testable markers for functional prognosis or targets for treatment.

Implications of Haptoglobin Genotype and Cardiovascular Risk in Patients with Diabetes

Haptoglobin (HAP) is genetically polymorphic with three primary genotypes, HAP 1-1, 2-1 and 2-2. Each genotype differs phenotypically in HAP structure and ability to perform its main function, scavenging free hemoglobin (Hb) released from old red blood cells. Patients with both diabetes and the genotype 2-2 appear to be at an increased cardiovascular risk than those with the other genotypes or patients without diabetes. This risk appears elevated with worse glycemic control. The exact mechanism for this increased risk is unknown but there are several proposed causes. Vitamin E has shown to reduce cardiovascular events in patients with both diabetes and the 2-2 genotype but the safety of implementing such therapy remains unknown. Recent post-hoc evaluation of a landmark study originally designed to assess the benefits and risks of more aggressive glycemic control suggests there may be a cardiovascular benefit in patients with diabetes and the 2-2 genotype that is not seen in those with the other genotypes. This information, if confirmed with post-hoc evaluation of other similar landmark studies as well as evaluation of genotype differences in recent cardiovascular safety studies with glucagon-like peptide agonists or sodium-glucose cotransporter inhibitors, could provide clinicians with an avenue to better identify patients most at risk for cardiovascular events and who may benefit the most from more aggressive glycemic control or use of other antihyperglycemic agents.

Investigating the Prevalence of Anaemia in Rural Gambia, in Relation to Levels of Zinc Protoporphyrin, Haemoglobin and Haptoglobin (Phenotype and Genotype)

Objectives To find out the overlapping and correlating relationships between serum haptoglobin level, haptoglobin genotype and phenotype, blood haemoglobin level and zinc protoporphyrin (measured in washed RBCs) in association to prevalence of anaemia. It will focus on comparing all the mention components in contrast to each other. The study will also look for the frequency distribution of the major HP alleles. Methods 1278 participants were randomly selected. Blood samples collected by trained nurses. Data generation was done at the Medical research council (keneba field station) research site. Data Analysis was conducted at the university of Chester with the assistance of the computer department team. Results P = 0.000 indicating anaemia prevalence with HP 1 allele. P &gt; 0.05 when ID, IDA and AI relates with HP genotype. Positive correlation between ZnPP and HP serum level, but negative between ZnPP and Hb. P = 0.000 between ZnPP and IDA. P = 0.024 between HP genotype and Hb level. P = 0.013 between HP genotype and HP serum. P = 0.100 between HP genotype and ZnPP. P = 0.000 between ZnPP and IDA. P = 0.024 between HP genotype and Hb. ZnPP shared a positive correlation with HP serum level, and a negative correlation with Hb level. The correlation significant = 0.01 level (2-tailed) P = 0.01. The correlation between HP genotype and HP serum level was significant with P = 0.013, but the correlation between HP genotype and ZnPP was not significant with P = 0.100. Conclusions HP genotype had association with anaemia prevalence and more occurrence was observed in carriers of the type ‘1’ allele. It had no association with ID, IDA and AI. HP genotype had association with HP serum level and Hb level but had no association with ZnPP level. ZnPP level was observed to have had association with HP serum level, Hb level and IDA; but had no association with ID and AI in the region. Funding Sources All the resources used in this study were from MRC Keneba (International Nutrition Group) which is supported by funds from the UK Medical Research Council (MRC) and the UK Department for International Development (DFID) under the MRC/DFID Concordat agreement (Hennig et al., 2015).