title: The albinism of the feral Asinara white donkeys (Equus asinus) is determined by a missense mutation in a highly conserved position of the tyrosinase (TYR) gene deduced protein.
abstract: A feral donkey population (Equus asinus), living in the Asinara National Park (an island north-west of Sardinia, Italy), includes a unique white albino donkey subpopulation or colour morph that is a major attraction of this park. Disrupting mutations in the tyrosinase (TYR) gene are known to cause recessive albinisms in humans (oculocutaneous albinism Type 1; OCA1) and other species. In this study, we analysed the donkey TYR gene as a strong candidate to identify the causative mutation of the albinism of these donkeys. The TYR gene was sequenced from 13 donkeys (seven Asinara white albino and six coloured animals). Seven single nucleotide polymorphisms were identified. A missense mutation (c.604C>G; p.His202Asp) in a highly conserved amino acid position (even across kingdoms), which disrupts the first copper-binding site (CuA) of functional protein, was identified in the homozygous condition (G/G or D/D) in all Asinara white albino donkeys and in the albino son of a trio (the grey parents had genotype C/G or H/D), supporting the recessive mode of inheritance of this mutation. Genotyping 82 donkeys confirmed that Asinara albino donkeys had genotype G/G whereas all other coloured donkeys had genotype C/C or C/G. Across-population association between the c.604C>G genotypes and the albino coat colour was highly significant (P = 6.17E-18). The identification of the causative mutation of the albinism in the Asinara white donkeys might open new perspectives to study the dynamics of this putative deleterious allele in a feral population and to manage this interesting animal genetic resource.
authors.affiliation: Department of Agricultural and Food Sciences, Division of Animal Sciences, University of Bologna, Viale Fanin 46, 40127, Bologna, Italy.
authors.forename: V J
authors.initials: VJ
authors.lastname: Utzeri
authors.affiliation: Department of Agricultural and Food Sciences, Division of Animal Sciences, University of Bologna, Viale Fanin 46, 40127, Bologna, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Bertolini
authors.affiliation: Department of Agricultural and Food Sciences, Division of Animal Sciences, University of Bologna, Viale Fanin 46, 40127, Bologna, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Ribani
authors.affiliation: Department of Agricultural and Food Sciences, Division of Animal Sciences, University of Bologna, Viale Fanin 46, 40127, Bologna, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Schiavo
authors.affiliation: Department of Agricultural and Food Sciences, Division of Animal Sciences, University of Bologna, Viale Fanin 46, 40127, Bologna, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Dall'Olio
authors.affiliation: Department of Agricultural and Food Sciences, Division of Animal Sciences, University of Bologna, Viale Fanin 46, 40127, Bologna, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Fontanesi
mesh_terms: D000417:Albinism / Q000235:genetics*; D000818:Animals; D001947:Breeding; D018397:Equidae / Q000235:genetics*; D005808:Genes, Recessive; D005838:Genotype; D007558:Italy; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000235:genetics*; D020125:Mutation, Missense; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide
chemical_list: D014442:Monophenol Monooxygenase
keywords: Asinara island; coat colour; deleterious mutation; equid; oculocutaneous albinism Type 1; pigmentation; population genetics