Haptoglobin Gene Polymorphism in Patients with Sickle Cell Anemia: Findings from a Nigerian Cohort Study

Involvement of haptoglobin in disease development

Haptoglobin (HP) is a liver glycoprotein that is actively synthesized during inflammatory and hemolytic processes. It also has pro-oxidant and proinflammatory properties, which are a function of its genotype. The genetic polymorphism of the chains leads to synthesis of three phenotypes/proteins, which are related to the number and type of chains and their molecular weight, namely HP1-1, HP1-2 and HP2-2. Patients with HP2-2 have more vascular complications, while those with HP1-1 have fewer. HP is involved in the worsening of diseases, such as HP2-2 in aggravation of vaso-occlusive crises in sickle cell disease, and worsening of the pathophysiology of other diseases. In contrast, HP1-1 confers better protection against diseases. All of this suggests that further studies should be conducted, including experimental and analytical studies focused on demonstrating the influence of different HP genotypes on individual clinical and hematological data. This would help in understanding the role played by this genetic polymorphism in the pathophysiology of diseases.

Unlocking the link between haptoglobin polymorphism and noninfectious human diseases: insights and implications

Haptoglobin (Hp) is a polymorphic protein that was initially described as a hemoglobin (Hb)-binding protein. The major functions of Hp are to scavenge Hb, prevent iron loss, and prevent heme-based oxidation. Hp regulates angiogenesis, nitric oxide homeostasis, immune responses, and prostaglandin synthesis. Genetic polymorphisms in the Hp gene give rise to different phenotypes, including Hp 1-1, Hp 2-1, and Hp 2-2. Extensive research has been conducted to investigate the association between Hp polymorphisms and several medical conditions including cardiovascular disease, inflammatory bowel disease, cancer, transplantation, and hemoglobinopathies. Generally, the Hp 2-2 phenotype is associated with increased disease risk and poor outcomes. Over the years, the Hp 2 allele has spread under genetic pressures. Individuals with the Hp 2-2 phenotype generally exhibit lower levels of CD163 expression in macrophages. The decreased expression of CD163 may be associated with the poor antioxidant capacity in the serum of subjects carrying the Hp 2-2 phenotype. However, the Hp 1-1 phenotype may confer protection in some cases. The Hp1 allele has strong antioxidant, anti-inflammatory, and immunomodulatory properties. It is important to note that the benefits of the Hp1 allele may vary depending on genetic and environmental factors as well as the specific disease or condition under consideration. Therefore, the Hp1 allele may not necessarily confer advantages in all situations, and its effects may be context-dependent. This review highlights the current understanding of the role of Hp polymorphisms in cardiovascular disease, inflammatory bowel disease, cancer, transplantation, hemoglobinopathies, and polyuria.

Haptoglobin gene polymorphism and iron profile in sickle cell disease patients with inflammation in Yaounde, Cameroon

BACKGROUND

Major sickle cell syndromes are the most common hemoglobinopathy in the world. The sickle cell patients are subjected to several factors causing inflammation, and the genetic identification of each individual allows to focus the possibility of allelic variations influence of a specific gene and then the polymorphism. This study aims at determining the distribution of HP gene (OMIM#140100) and their involvement on hematological parameters and the iron profile in the sickle cell patients presenting an inflammation condition during major sickle cell syndromes in Cameroun.

METHODS

A case-control analytical study has been conducted over a period of 6 months. Cases consisting of sickle cell patients in a situation of inflammation and control of non-inflamed sickle cell patients. The patients presenting major sickle cell syndromes, interned and/or followed at the Hematology Department of the Regional Hospital of Bafoussam and the Central Hospital of Yaoundé have been recruited. HP genotyping was carried out at the Laboratory for Public Health Research Biotechnologies (LAPHER-Biotech) in Yaoundé using allele-specific PCR. Also, inflammatory, hematological parameters and martial assessment were explored by standard methods. Statistical analysis of the data was performed using the statistical tool R version 4.1.1. The comparison of proportions of alleles was made with the chi-square test, and the Wilcoxon test was used to compare the median between different groups using the statistical tool R version 4.1.1.

RESULTS

We analyzed the samples of 149 patients. The HP polymorphism describes a significant frequency of the "1F" allele (69.8%) followed by the "2" allele (46.31%). In addition, 80 patients (53.69%), 48 (32.21%), and 21 (14.09%) presented the genotype HP 1-1, HP 2-1, and HP 2-2, respectively. And eighty-one percent (81%) patients with genotype HP 2-2 showed a significant higher relative frequency of thrombocytosis compared with the genotype HP 1-1 and HP 2-1, respectively (51.2% and 68.8%, p = 0.087). The proportion of inflammation in the HP 2-2 group was higher (57.1%) compared with the other groups (respectively 42.5% and 35.4% in the HP 1-1 and HP 2-1 groups). Furthermore, the median CRP was significantly higher in the HP 2-2 group compared with the other groups (p = 0.039). Moreover, the entire population of the HP 2-2 group showed an elevation of ferritin and IL6 unlike the HP 1-1 and HP 2-1 groups.

CONCLUSION

This study demonstrates a higher frequency of genotype HP 1-1 followed by the HP 2-2 genotype in patients with major sickle cell syndromes. However, a larger proportion of patients with genotype HP 2-2 are associated with hematological profile disorders, inflammation, and dysregulation of iron metabolism. Then, the haptoglobin polymorphism contributes to the severity of major sickle cell syndromes.

Haptoglobin gene polymorphism and iron profile in sickle cell disease patients with inflammation in Yaounde, Cameroon

Background

Major sickle cell syndromes are the most common hemoglobinopathy in the world. The sickle cell patients are subjected to several factors causing inflammation, and the genetic identification of each individual allows to focus the possibility of allelic variations influence of a specific gene and then the polymorphism. This study aims at determining the distribution of HP gene (OMIM#140100) and their involvement on hematological parameters and the iron profile in the sickle cell patients presenting an inflammation condition during major sickle cell syndromes in Cameroun.

Methods

A case–control analytical study has been conducted over a period of 6 months. Cases consisting of sickle cell patients in a situation of inflammation and control of non‐inflamed sickle cell patients. The patients presenting major sickle cell syndromes, interned and/or followed at the Hematology Department of the Regional Hospital of Bafoussam and the Central Hospital of Yaoundé have been recruited. HP genotyping was carried out at the Laboratory for Public Health Research Biotechnologies (LAPHER‐Biotech) in Yaoundé using allele‐specific PCR. Also, inflammatory, hematological parameters and martial assessment were explored by standard methods. Statistical analysis of the data was performed using the statistical tool R version 4.1.1. The comparison of proportions of alleles was made with the chi‐square test, and the Wilcoxon test was used to compare the median between different groups using the statistical tool R version 4.1.1.

Results

We analyzed the samples of 149 patients. The HP polymorphism describes a significant frequency of the “1F” allele (69.8%) followed by the “2” allele (46.31%). In addition, 80 patients (53.69%), 48 (32.21%), and 21 (14.09%) presented the genotype HP 1‐1, HP 2‐1, and HP 2‐2, respectively. And eighty‐one percent (81%) patients with genotype HP 2‐2 showed a significant higher relative frequency of thrombocytosis compared with the genotype HP 1‐1 and HP 2‐1, respectively (51.2% and 68.8%, p = 0.087). The proportion of inflammation in the HP 2‐2 group was higher (57.1%) compared with the other groups (respectively 42.5% and 35.4% in the HP 1‐1 and HP 2‐1 groups). Furthermore, the median CRP was significantly higher in the HP 2‐2 group compared with the other groups (p = 0.039). Moreover, the entire population of the HP 2‐2 group showed an elevation of ferritin and IL6 unlike the HP 1‐1 and HP 2‐1 groups.

Conclusion

This study demonstrates a higher frequency of genotype HP 1‐1 followed by the HP 2‐2 genotype in patients with major sickle cell syndromes. However, a larger proportion of patients with genotype HP 2‐2 are associated with hematological profile disorders, inflammation, and dysregulation of iron metabolism. Then, the haptoglobin polymorphism contributes to the severity of major sickle cell syndromes.

Influence of Haptoglobin Polymorphism on Stroke in Sickle Cell Disease Patients

This review outlines the current clinical research investigating how the haptoglobin (Hp) genetic polymorphism and stroke occurrence are implicated in sickle cell disease (SCD) pathophysiology. Hp is a blood serum glycoprotein responsible for binding and removing toxic free hemoglobin from the vasculature. The role of Hp in patients with SCD is critical in combating blood toxicity, inflammation, oxidative stress, and even stroke. Ischemic stroke occurs when a blocked vessel decreases oxygen delivery in the blood to cerebral tissue and is commonly associated with SCD. Due to the malformed red blood cells of sickle hemoglobin S, blockage of blood flow is much more prevalent in patients with SCD. This review is the first to evaluate the role of the Hp polymorphism in the incidence of stroke in patients with SCD. Overall, the data compiled in this review suggest that further studies should be conducted to reveal and evaluate potential clinical advancements for gene therapy and Hp infusions.

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, Hp^1S: 0.304, and Hp^1F: 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 Hp^1S and 0.218 for Hp^1F in AS and 0.283 for Hp^1S and 0.258 for Hp^1F 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.

Determinants of Care-Seeking Practices for Children with Sickle Cell Disease in Ekiti, Southwest Nigeria

Background

Due to the chronic nature of sickle cell disease (SCD), affected individuals may seek help from diverse places thus raising the need to understand their health-seeking behavior (HSB) in order to design an appropriate management policy for them.

Aim

The aim of this study was to evaluate the HSB among pediatric SCD patients relative to their non-SCD counterparts attending a tertiary facility in Southwest Nigeria and identified predictors of poor HSB among SCD patients.

Methods

A total of 110 children with SCD were recruited and studied for their HSPs which were compared with 110 non-SCD patients with other chronic medical conditions. Questionnaires were used to obtain self-reported information on participants’ socio-demographic data and HSB. Logistic regression was used to determine the predictors of poor HSB among the SCD cohort.

Results

More SCD patients received treatments at private hospitals, patent medicine stores and faith-based centers compared to their non-SCD counterparts (p=0.0052; 0.006; and 0.007), respectively. No difference was observed in the patronage of traditional care centres 10 (9.1%) vs 6 (5.5%). More SCD patients 61 (55.5%) vs 35 (31.8%) exhibited poor HSB (p=0.0004). SCD patients who were not enrolled on health insurance scheme were 18 times more likely to have poor HSB (OR=18.38, 95% CI (4.41–76.57), p value= <0.0001) while absence of VOC within the preceding year reduces the risk of poor HSB by 91.5% (OR=0.085, 95% CI (0.028–0.258), p value= <0.0001).

Conclusion

SCD patients in the study locality had poor HSB. This raises the need for their education on proper HSB. More enrollment into health insurance scheme and the prevention of VOC will lessen the burden of poor HSB. The high patronage of non-hospital care facilities in this study raises the need for stakeholders to monitor activities and train the operators at these informal care centres.