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

Abstract

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.

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

“…However, these clinical features and anthropometric parameters were not significantly associated with a particular haptoglobin genotype (p > 0.05); we can also note significant differences for bacterial infections and vaso-occlusive crises suggesting that the presence of the "HP 2 " allele is a parameter favoring these clinical manifestations. This observation has also been reported by several authors (Bernard et al, 2021;Ostrowski et al, 1987;Park et al, 2004;Soejima & Koda, 2020).…”

“…It is also similar to that of Khalid and Khalil (2016) in Sudan, which reported respective frequencies of 67.5% for HP 1-1, 26.5% for HP 2-1, and 6.3% for HP 2-2 and that of Ostrowski et al (1987) which reported 72% for HP 1-1, 11% for HP 2-1, and 12% for HP 2-2. In contrast, these results are different from those of Bruna et al (2015) (Bernard et al, 2021). A variability in the distribution of haptoglobin genotypes in the population is reported also by Santos et al (2011) in Brazil.…”

“…(2015) which reported 16.7% of HP 1‐1, 56.7% of HP 2‐1, and 26.6% of HP 2‐2 (Pierrot‐Gallo et al., 2015) and those of Kengne et al. (2021) which reported 31.4% of HP 1‐1, 14.7% of HP 2‐1, and 53.9% of HP 2‐2 (Bernard et al., 2021). A variability in the distribution of haptoglobin genotypes in the population is reported also by Santos et al.…”

Haptoglobin 1 allele predicts higher serum haptoglobin concentration and lower multiorgan failure risk in sickle cell disease

“… 13 , 14 Studies in patients with SCD have also shown mixed results, with some demonstrating that the HP 1 allele is associated with fewer SCD-related complications 15 , 16 and others not reporting differences by the HP genotype. 17 , 18 …”

“…13,14 Studies in patients with SCD have also shown mixed results, with some demonstrating that the HP 1 allele is associated with fewer SCD-related complications 15,16 and others not reporting differences by the HP genotype. 17,18 We conducted a longitudinal study to determine whether the (1) HP genotype is associated with HP and cell-free hemoglobin concentrations at steady state, VOE, and acute chest syndrome; and (2) HP 1 allele is protective against developing multiorgan failure during an episode of acute chest syndrome.…”