Genetic linkage of mild malaria to the major histocompatibility complex in Gambian children: study of affected sibling pairs

摘要

Case-control studies have shown that genes for the major histocompatibility complex influence the presentation and outcome of severe Plasmodium falciparum disease (cerebral malaria or severe anaemia). To assess the role of these genes in mild disease, we conducted a genetic analysis of sibling pairs concordant for this phenotype. The affected sib-pair method compares the observed and expected distribution of parental alleles at marker loci inherited identical by descent (ibd). At any locus, a pair of siblings may share 0, 1, or 2 alleles in the ratio 25%:50%:25%, by random segregation. If a locus is genetically linked to disease, affected siblings will share a higher number of alleles identical by descent at that locus than expected.