The haptoglobin promoter polymorphism rs5471 is the most definitive genetic determinant of serum haptoglobin level in a Ghanaian population.

BACKGROUND: The serum haptoglobin (HP) level varies in various clinical conditions and among individuals. Recently, the common HP alleles, rs5472, and rs2000999 have been reported to associate with serum HP level, but no studies have been done on Africans. Here, we explored the relationship of not only these polymorphisms but also rs5470 and rs5471 to the serum HP level in 121 Ghanaians. METHODS: Genotyping of rs2000999 was performed by PCR using hydrolysis probes, while the other polymorphisms have been already genotyped. Serum HP level was measured by a sandwich ELISA. RESULTS: We observed a significant association between rs5471 and the serum HP level (p = 0.026). It was also observed within the subgroups of HP2/HP2 and HP2/HP1. In addition, we detected a trend toward lower HP levels for individuals with the A allele of rs2000999 than those without A, but it was not statistically significant (p = 0.156). However, we did not observe the clear associations between other polymorphisms and serum HP level that were observed for Europeans and Asians because of the small sample size and the complexity of SNPs affecting the HP level. CONCLUSIONS: We suggest that rs5471 is a strong genetic determinant of HP levels in Ghanaians, and this seems to be characteristic of Africans. Further investigation using large scale samples will help in understanding the genetic background of individual variability of the serum HP level.

Smoking and haptoglobin phenotype modulate serum ferritin and haptoglobin levels in Parkinson disease.

The phenotype Hp 2-1 of haptoglobin has been previously associated with increased risk of Parkinson disease (PD) and with serum iron abnormalities in PD patients. Tobacco smoking has been consistently observed in epidemiology studies to be inversely related to PD risk, with mechanisms that remain uncertain. We recently observed that the protective effect of smoking on PD risk is stronger among subjects of haptoglobin Hp 2-2 and Hp 1-1 phenotypes, and weaker among subjects of haptoglobin Hp 2-1 phenotype. In this PD case-control study, we investigated whether tobacco smoking was associated with changes in serum haptoglobin and ferritin concentration that depended on haptoglobin phenotype among 106 PD patients and 238 controls without PD or other neurodegenerative disorders. Serum ferritin concentration, serum haptoglobin concentration, haptoglobin phenotype, and smoking data information of cases and controls were obtained. Differences in haptoglobin and ferritin concentration by smoking status and pack-years of smoking were calculated as well as regression between pack-years and haptoglobin and ferritin concentration, and the effect of haptoglobin phenotype on these parameters. Tobacco smoking was associated with an elevation in serum haptoglobin concentration, especially among healthy controls of haptoglobin Hp 2-2 phenotype, and with an elevation in ferritin concentration especially among PD patients of haptoglobin Hp 2-1 phenotype. These findings suggest that an elevation in haptoglobin concentration, preferentially among subjects of haptoglobin Hp 2-2 phenotype, could be a contributing factor to the protective effect of smoking on PD risk.