Characterization of CD28, CTLA4, and ICOS Polymorphisms in Three Brazilian Ethnic Groups

• Published in: Human Immunology Vol. 66; no. 7; pp. 773 - 776
• Main Authors: Guzman, V.B., Morgun, A., Shulzhenko, N., Mine, K.L., Gonçalves-Primo, A., Musatti, C.C., Gerbase-Delima, M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.07.2005
• Subjects: 3' Flanking Region - genetics; African Continental Ancestry Group - genetics; Alleles; Antigens, CD; Antigens, Differentiation - genetics; Antigens, Differentiation, T-Lymphocyte - genetics; Brazil; CD28; CD28 Antigens - genetics; CTLA-4 Antigen; CTLA4; European Continental Ancestry Group - genetics; Exons - genetics; Gene Frequency; gene polymorphisms; Genotype; Humans; ICOS; Inducible T-Cell Co-Stimulator Protein; Introns - genetics; Linkage Disequilibrium; Polymorphism, Single Nucleotide; Promoter Regions, Genetic - genetics; Brazil; CD28; CTLA4; ICOS; gene polymorphisms; linkage disequilibrium
• ISSN: 0198-8859; 1879-1166; 1365-2567
• DOI: 10.1016/j.humimm.2005.04.007

Costimulatory molecules CD28, CTLA-4 (cytotoxic T-lymphocyte-associated antigen-4), and ICOS (inducible costimulator) genes lie within the 300-kb chromosome region 2q33. CD28, CTLA-4, and ICOS have been described to be important regulators of T-cell activation. With the objective to study ethnic variations in allelic frequencies and linkage disequilibrium (LD) patterns, we genotyped CD28 intron 3 (+17 T>C), CTLA4 promoter (−319 C>T), CTLA4 exon 1 (+49 A>G), and ICOS 3′ UTR (1564 T>C) polymorphisms in white ( n = 103), mulatto ( n = 97), and black ( n = 79) Brazilian healthy individuals. No significant deviations from Hardy-Weinberg equilibrium were found in any of the population samples. A higher frequency of CD28 +17 C allele was detected in white (27%) in comparison with mulatto (15%) and black (13%) ( p = 0.005) populations. LD between CD28 +17 C and CTLA4 −319 T alleles was observed in whites ( p < 0.0001), mulattos ( p = 0.0001), and blacks ( p = 0.0002).