HP and HIV infectious disease: Hp is also thought to affect immune regulation, including the balance of Th1∶Th2 cytokine responses [35] and several studies have associated haptoglobin phenotypes and genotypes with a range of conditions including cardiovascular disease [36], diabetes [37], [38], HIV infection [39], [40], [41] and susceptibility to malaria [42], [43], [44], [45] including a protective association of the Hp haplotype containing the Hp2 and the C allele for the promoter -61A-C (rs5471) SNP in Gambian children [46].