title: MICA, HLA-B haplotypic variation in five population groups of sub-Saharan African ancestry.
abstract: The human major histocompatibility complex (MHC) class I chain-related gene A (MICA), located 46 kb centromeric to HLA-B, encodes a stress-inducible protein, which is a ligand for the NKG2D receptor. In addition to its primary role in immune surveillance, data suggest that MICA is involved in the immune response to transplants and in susceptibility to some diseases. In this study, 152 subjects from the Yoruba (n=74), Efik (n=32), and Igbo (n=46) tribes of southern Nigeria, 39 nationwide African-American stem cell donors, and 60 African-American individuals residing in the metropolitan Boston area were studied for MICA, HLA-B allelic variation, haplotypic diversity, and linkage disequilibrium (LD). MICA and HLA-B exhibited a high degree of genetic diversity among the populations studied. In particular, MICA allele and HLA-B-MICA haplotype frequencies and LD in the Efik and Igbo tribes were significantly different from the other study groups. HLA-B and MICA loci demonstrated significant global LD in all five populations (P-values &<0.00001). LD also varied in a haplotype-specific manner. A novel MICA allele was detected in the Boston population. These findings are important from an anthropologic perspective, and will inform future HLA-linked disease association studies in related ethnic groups of African-derived ancestry.
authors.affiliation: Center for Blood Research, Harvard Medical School, Boston, MA, USA. fraser@cbr.med.harvard.edu
authors.forename: W
authors.initials: W
authors.lastname: Tian
authors.forename: D A
authors.initials: DA
authors.lastname: Boggs
authors.forename: G
authors.initials: G
authors.lastname: Uko
authors.forename: A
authors.initials: A
authors.lastname: Essiet
authors.forename: M
authors.initials: M
authors.lastname: Inyama
authors.forename: B
authors.initials: B
authors.lastname: Banjoko
authors.forename: T
authors.initials: T
authors.lastname: Adewole
authors.forename: W-Z
authors.initials: WZ
authors.lastname: Ding
authors.forename: M
authors.initials: M
authors.lastname: Mohseni
authors.forename: R
authors.initials: R
authors.lastname: Fritz
authors.forename: D-F
authors.initials: DF
authors.lastname: Chen
authors.forename: L J
authors.initials: LJ
authors.lastname: Palmer
authors.forename: P A
authors.initials: PA
authors.lastname: Fraser
mesh_terms: D017954:Africa South of the Sahara; D000483:Alleles; D044383:Black People; D001900:Boston; D005787:Gene Frequency; D014644:Genetic Variation; D005828:Genetics, Population; D015235:HLA-B Antigens / Q000235:genetics*; D006239:Haplotypes; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006801:Humans; D015810:Linkage Disequilibrium; D018911:Trinucleotide Repeats; D001741:Black or African American
chemical_list: D015235:HLA-B Antigens; D015395:Histocompatibility Antigens Class I; C099187:MHC class I-related chain A