title: Extensive polymorphism of the major histocompatibility complex DRA gene in Balkan donkeys: perspectives on selection and genealogy.
abstract: The major histocompatibility complex (MHC) contains genes important for immune response in mammals, and these genes exhibit high polymorphism and diversity. The DRA gene, a member of the MHC class II family, is highly conserved across a large number of mammalian species, but it displays exceptionally rich sequence variations in Equidae members. We analyzed allelic polymorphism of the DRA locus in 248 donkeys sampled across the Balkan Peninsula (Albania, Bulgaria, Croatia, Macedonia, Greece and Montenegro). Five known alleles and two new alleles were identified. The new allele Eqas-DRA*0601 was found to carry a synonymous mutation, and new allele Eqas-DRA*0701, a non-synonymous mutation. We further analyzed the historical selection and allele genealogy at the DRA locus in equids. Signals of positive selection obtained by various tests were ambiguous. A conservative conclusion is that DRA polymorphism occurred relatively recently and that positive selection has been acting on the DRA locus for a relatively brief period.
authors.affiliation: Division of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, 10000, Zagreb, Croatia.
authors.forename: Haidi
authors.initials: H
authors.lastname: Arbanasić
authors.forename: Ana
authors.initials: A
authors.lastname: Galov
authors.forename: Andreja
authors.initials: A
authors.lastname: Ambriović-Ristov
authors.forename: Juraj
authors.initials: J
authors.lastname: Grizelj
authors.forename: Georgios
authors.initials: G
authors.lastname: Arsenos
authors.forename: Božidarka
authors.initials: B
authors.lastname: Marković
authors.forename: Toni
authors.initials: T
authors.lastname: Dovenski
authors.forename: Silvijo
authors.initials: S
authors.lastname: Vince
authors.forename: Ino
authors.initials: I
authors.lastname: Curik
mesh_terms: D000483:Alleles; D000818:Animals; D063368:Balkan Peninsula; D001483:Base Sequence; D027963:Chloride-Bicarbonate Antiporters / Q000235:genetics*; D018397:Equidae / Q000235:genetics*; D005787:Gene Frequency / Q000235:genetics; D005802:Genes, MHC Class II / Q000235:genetics*; D005828:Genetics, Population; D016013:Likelihood Functions; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000662:veterinary; D011110:Polymorphism, Genetic / Q000235:genetics*; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA / Q000662:veterinary
chemical_list: D027963:Chloride-Bicarbonate Antiporters
keywords: DRA locus; donkey; genetic diversity; major histocompatibility complex; selection