title: Characterization of CD28, CTLA4, and ICOS polymorphisms in three Brazilian ethnic groups.
abstract: 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).
authors.affiliation: Division of Immunogenetics, Department of Pediatrics, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil.
authors.forename: V B
authors.initials: VB
authors.lastname: Guzman
authors.forename: A
authors.initials: A
authors.lastname: Morgun
authors.forename: N
authors.initials: N
authors.lastname: Shulzhenko
authors.forename: K L
authors.initials: KL
authors.lastname: Mine
authors.forename: A
authors.initials: A
authors.lastname: Gonçalves-Primo
authors.forename: C C
authors.initials: CC
authors.lastname: Musatti
authors.forename: M
authors.initials: M
authors.lastname: Gerbase-Delima
mesh_terms: D024509:3' Flanking Region / Q000235:genetics; D000483:Alleles; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000235:genetics*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics; D044383:Black People / Q000235:genetics*; D001938:Brazil; D018106:CD28 Antigens / Q000235:genetics; D060908:CTLA-4 Antigen; D005091:Exons / Q000235:genetics; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D060889:Inducible T-Cell Co-Stimulator Protein; D007438:Introns / Q000235:genetics; D015810:Linkage Disequilibrium; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic / Q000235:genetics; D044465:White People / Q000235:genetics*
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D000945:Antigens, Differentiation, T-Lymphocyte; D018106:CD28 Antigens; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; C556692:ICOS protein, human; D060889:Inducible T-Cell Co-Stimulator Protein