title: Absence of the HLA-G*0105N allele in Amerindian populations from the Brazilian Amazon Region: a possible role of natural selection.
abstract: The human leukocyte antigen G (HLA-G) null allele (G*0105N) is defined by a DeltaC deletion at exon 3. Its high frequency in populations from areas with high pathogen loads and the putative role of HLA-G in placental development suggest that the reduced G1 expression in G*0105N heterozygous placentas may improve the intrauterine defense against infections. The G*0105N allele frequencies were evaluated in 143 Amerindians from six isolated tribes that inhabit the Central Amazon to determine the existence of genotype frequencies that suggest balancing selection in favor of G*0105N heterozygotes. No copy of the null allele was found by exon 3 sequencing. Although this finding may be because of demographic or other selective factors, it also suggests no evidence of G*0105N heterozygous advantage.
authors.affiliation: Division of Clinical Immunology, Department of Medicine, School of Medicine of Ribeirão Preto, University of São Paulo, Avenida Bandeirantes 3900, 14049-900 Ribeirão Preto, São Paulo, Brazil. ctmendes@rge.fmrp.usp.br
authors.forename: C T
authors.initials: CT
authors.lastname: Mendes-Junior
authors.forename: E C
authors.initials: EC
authors.lastname: Castelli
authors.forename: A L
authors.initials: AL
authors.lastname: Simões
authors.forename: E A
authors.initials: EA
authors.lastname: Donadi
mesh_terms: D000483:Alleles; D001938:Brazil; D005260:Female; D005787:Gene Frequency; D005828:Genetics, Population; D005838:Genotype; D006680:HLA Antigens / Q000235:genetics*; D059951:HLA-G Antigens; D006801:Humans; D007199:Indians, South American / Q000235:genetics*; D008297:Male; D011110:Polymorphism, Genetic; D012641:Selection, Genetic
chemical_list: D006680:HLA Antigens; D059951:HLA-G Antigens; C420206:HLA-G*01:05N antigen