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The first structural IFNG variant, G54D (c.287G>A, ss105106770), located in the second exon, was identified.

A mutation at position -308 of the tumor necrosis factor alpha (TNF-308A) gene promoter has previously been associated with particular manifestations of infectious and non-infectious diseases. In a longitudinal study on malariological parameters in Gabon, TNF promoter variants of 98 children initially presenting with severe Plasmodium falciparum malaria, followed by a total of 504 reinfection events within 52 months, and 100 children initially presenting with mild malaria followed by a total of 342 reinfections were analyzed. Symptomatic P. falciparum reinfections occurred more quickly (median 11 weeks) in carriers of the TNF-308A allele, with severe malaria at enrollment, compared to carriers of other TNF promoter variants (median 16 weeks). The results show that this particular TNF promoter allele increases the risk of reinfection with the malaria parasite P. falciparum.

The frequencies of DPA1 and DPB1 alleles and their occurrence in haplotypic linkage were assessed and compared in Nigerian, Liberian, and Gabonese individuals. Differences were seen in the distribution patterns; these differences were more pronounced between the Gabonese and the other two populations than between Liberians and Nigerians. Several haplotypic DPA1-DPB1 combinations could be verified by homozygosity. Linkage disequilibria of DPA1-DPB1 combinations, indicating further probable haplotypes, were estimated. Although different allele and haplotype frequencies were recognized in the three subgroups, the linkage disequilibria were mostly either positive or negative in all populations.

HLA class II DRB1-DQA1-DQB1 haplotypic polymorphism was determined in 120 Liberian and 230 Gabonese individuals. In our study groups, the number of allelic variants observed for each locus was similar to that found in non-African populations. However, 39 novel haplotypes and several yet unrecognized DRB1-DQA1 and DQA1-DQB1 combinations were identified. The extent of HLA-haplotypic variability in Africans appears to result from the high degree of allele combinations rather than from allelic polymorphism.