title: High variability of TLR4 gene in different ethnic groups in Iran.
abstract: Infectious diseases exert a constant evolutionary pressure on the innate immunity genes. TLR4, an important member of the TLR family, specifically recognizes conserved structures of various infectious pathogens. Two functional TLR4 polymorphisms, Asp299Gly and Thr399Ile, modulate innate host defense against infections, and their prevalence between various populations has been proposed to be influenced by local infectious pressures. If this assumption is true, strong local infectious pressures would lead to a homogeneous pattern of these ancient TLR4 polymorphisms in geographically-close populations, while a weak selection or genetic drift may result in a diverse pattern. We evaluated TLR4 polymorphisms in 15 ethnic groups in Iran, to assess whether infections exerted selective pressures on different haplotypes containing these variants. The Iranian subpopulations displayed a heterogeneous pattern of TLR4 polymorphisms, comprising various percentages of Asp299Gly and Thr399Ile, alone or in combination. The Iranian sample, as a whole, showed an intermediate mixed pattern when compared with commonly-found patterns in Africa, Europe, Eastern Asia and the Americas. These findings suggest a weak, or absent, selection pressure on TLR4 polymorphisms in the Middle-East that does not support the assumption of an important role of these polymorphisms in the host defense against local pathogens.
authors: Radboud University Nijmegen Medical Centre, and Nijmegen Institute for Infection, Inflammation and Immunity (N4i), Department of Medicine, Nijmegen, The Netherlands.
authors: Mihai
authors: M
authors: Ioana
authors: Bart
authors: B
authors: Ferwerda
authors: Shirin
authors: S
authors: Farjadian
authors: Luiza
authors: L
authors: Ioana
authors: Abbas
authors: A
authors: Ghaderi
authors: Marije
authors: M
authors: Oosting
authors: Leo A B
authors: LA
authors: Joosten
authors: Jos W M
authors: JW
authors: van der Meer
authors: Giovanni
authors: G
authors: Romeo
authors: Donata
authors: D
authors: Luiselli
authors: Dan
authors: D
authors: Dediu
authors: Mihai G
authors: MG
authors: Netea
mesh_terms: D003141:Communicable Diseases / Q000235:genetics*; D005006:Ethnicity / Q000235:genetics; D005787:Gene Frequency; D040961:Genetic Drift; D020022:Genetic Predisposition to Disease; D006239:Haplotypes; D054884:Host-Pathogen Interactions / Q000235:genetics; D006801:Humans; D007113:Immunity, Innate / Q000235:genetics; D007492:Iran / Q000208:ethnology; D020641:Polymorphism, Single Nucleotide; D051197:Toll-Like Receptor 4 / Q000235:genetics*
chemical_list: D051197:Toll-Like Receptor 4