Amazonian Amerindians exhibit high variability of KIR profiles

Abstract

Natural killer cell immunoglobulin-like receptors (KIRs) mediate cell lysis through the recognition of human leukocyte antigen class I complexes in target cells, playing an important role in innate immune response. In this context, disease-based selective pressures could be relevant, leaving signatures detected by population studies. However, most population studies on KIR variability have focused on Europe and Asia, while Americas, Oceania, and Africa remain poorly studied. The aim of this study was to analyze the variability of KIR genes in Amerindian tribes from the Amazon region to infer about their evolutionary history. KIR profiles were estimated in 40 individuals from six Amazonian Amerindian tribes using single specific primer polymerase chain reaction. Twenty-five different profiles were identified, and surprisingly, the haplogroup A frequency was the lowest observed in human populations (16%). Results showed also that KIR variability was higher in this group in contrast to Venezuelan Amerindians. Principal components analysis evidenced that Amerindians formed a separated group from other worldwide populations and showed a higher intraethnic differentiation in comparison to other ethnic groups. Such pattern may reflect small effective size and intense genetic drift. However, because of the role of KIR in immune response, selective pressures cannot be entirely ruled out.

Killer cell immunoglobulin-like receptor gene diversity in a Southern Brazilian population from the state of Paraná

“…The observed frequencies were compared with that of other populations [15,17,19,20,28,32,33,37,38,42] and proved to be consistent with those of the Caucasian populations.…”

“…The KIR gene frequencies for this population of Paran and other populations from the North, Central and South America, Europe, Africa, Australia, and Asia are presented in Table 2 [15,17,19,20,28,32,33,37,38,42]. The comparison between this studied population and the above-mentioned population demonstrated significant differences.…”

“…Ewerton et al [37] indicated that Amazonian Brazilians (Amerindians) formed a group that was separate from other worldwide populations, possibly because of intense genetic drift or different selective pressures. A distinct KIR pattern was observed between the Amazonian Amerindians and the population of ParanÂ.…”

Co-evolution of KIR2DL3 with HLA-C in a human population retaining minimal essential diversity of KIR and HLA class I ligands

“…The one KIR gene missing from the Yucpa, KIR2DS3 is of questionable function, because its protein product is not cell-surface expressed (27). And in the Yucpa, and other Amerindian groups, the absence of KIR2DS3 is compensated by increased frequency of the closely related KIR2DS5 (25,(38)(39)(40). The polymorphic KIR genes of the Yucpa retain the breadth of the polymorphism worldwide with three to four alleles, and similar numbers of HLA class I allotypes provide the three major epitopes recognized by KIR: C2 carried by HLA-C, C1 carried by HLA-C and HLA-B, and Bw4 carried by HLA-A and HLA-B.…”

Comparison of KIR gene content profiles revealed a difference between northern and southern Persians in the distribution of KIR2DS5 and its linked loci

“…Inheritance of distinct paternal and maternal haplotypes (A ϩ A, A ϩ B, or B ϩ B) generates extraordinary diversity in humans, ranging from those having dominant inhibitory (AA genotype), dominant activating (BB genotype), or balanced (AB genotype) KIR genotypes. Individuals carrying a dominant inhibitory KIR genotype are common in Chinese, Japanese, and Korean populations [13,18,19], whereas individuals carrying dominant activating KIR genotypes are common in the natives of North America [20,21], Australia [22], and India [23][24][25]. Caucasians and Africans have balanced KIR genotypes [17].…”