Browsing by Author "Chazara, Olympe"

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    Killer cell immunoglobulin-like receptor (KIR) genes and their HLA-C ligands in a Ugandan population
    (Immunogenetics, 2013) Nakimuli, Annettee; Chazara, Olympe; Farrell, Lydia; Hiby, Susan E.; Tukwasibwe, Stephen; Knee, Olatejumoye; Jayaraman, Jyothi; Traherne, James A.; Elliott, Alison M.; Kaleebu, Pontiano; Mirembe, Florence; Moffett, Ashley
    Killer cell immunoglobulin-like receptor (KIR) genes are expressed by natural killer cells and encoded by a family of genes exhibiting considerable haplotypic and allelic variation. HLA-C molecules, the dominant ligands for KIR, are present in all individuals and are discriminated by two KIR epitopes, C1 and C2.We studied the frequencies of KIR genes and HLA-C1 and C2 groups in a large cohort (n=492) from Kampala, Uganda, East Africa and compared our findings with published data from other populations in sub-Saharan Africa (SSA) and several European populations. We find considerably more KIR diversity and weaker linkage disequilibrium in SSA compared to the European populations and describe several novel KIR genotypes. C1 and C2 frequencies were similar to other SSA populations with a higher frequency of the C2 epitope (54.9 %) compared to Europe (average 39.7 %). Analysis of this large cohort from Uganda in the context of other African populations reveals variations in KIR and HLA-C1 and C2 that are consistent with migrations within Africa and potential selection pressures on these genes. Our results will help understand how KIR/HLA-C interactions contribute to resistance to pathogens and reproductive success.
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    A KIR B centromeric region present in Africans but not Europeans protects pregnant women from pre-eclampsia.
    (A KIR B centromeric region present in Africans but not Europeans protects pregnant women from pre-eclampsia., 2015) Nakimuli, Annettee; Chazara, Olympe; Hiby, Susan E.; Farrell, Lydia; Tukwasibwe, Stephen; Jayaraman, Jyothi; Traherne, James A.; Trowsdale, John; Colucci, Francesco; Lougee, Emma; Vaughan, Robert W.; Elliott, Alison M.; Byamugisha, Josaphat; Kaleebu, Pontiano; Mirembe, Florence; Nemat-Gorgani, Neda; Parham, Peter; Norman, Paul J.; MoffettMoffett, Ashley
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    Pregnancy, parturition and preeclampsia in women of African ancestry
    (American journal of obstetrics and gynecology,, 2014) Nakimuli, Annettee; Chazara, Olympe; Byamugisha, Josaphat; Elliott, Alison M.; Kaleebu, Pontiano; Mirembe, Florence; Moffett, Ashley
    Maternal and associated neonatal mortality rates in sub-Saharan Africa remain unacceptably high. In Mulago Hospital (Kampala, Uganda), 2 major causes of maternal death are preeclampsia and obstructed labor and their complications, conditions occurring at the extremes of the birthweight spectrum, a situation encapsulated as the obstetric dilemma. We have questioned whether the prevalence of these disorders occurs more frequently in indigenous African women and those with African ancestry elsewhere in the world by reviewing available literature. We conclude that these women are at greater risk of preeclampsia than other racial groups. At least part of this susceptibility seems independent of socioeconomic status and likely is due to biological or genetic factors. Evidence for a genetic contribution to preeclampsia is discussed. We go on to propose that the obstetric dilemma in humans is responsible for this situation and discuss how parturition and birthweight are subject to stabilizing selection. Other data we present also suggest that there are particularly strong evolutionary selective pressures operating during pregnancy and delivery in Africans. There is much greater genetic diversity and less linkage disequilibrium in Africa, and the genes responsible for regulating birthweight and placentation may therefore be easier to define than in non-African cohorts. Inclusion of African women into research on preeclampsia is an essential component in tackling this major disparity of maternal health