Extensive polymorphism of the major histocompatibility complex DRA gene in Balkan donkeys: perspectives on selection and genealogy

Arbanasić, Haidi; Galov, Ana; Ambriović-Ristov, Andreja; Grizelj, Juraj; Arsenos, Georgios; Marković, Božidarka; Dovenski, Toni; Vince, Silvijo; Curik, Ino

doi:10.1111/age.12054

Extensive polymorphism of the major histocompatibility complex DRA gene in Balkan donkeys: perspectives on selection and genealogy

Journal

Animal genetics

Date Issued

2013-12

Author(s)

Arbanasić, Haidi

Galov, Ana

Ambriović-Ristov, Andreja

Grizelj, Juraj

Arsenos, Georgios

Marković, Božidarka

Vince, Silvijo

Curik, Ino

DOI

10.1111/age.12054

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.