Bovine polledness--an autosomal dominant trait with allelic heterogeneity.
The persistent horns are an important trait of speciation for the family Bovidae with complex morphogenesis taking place briefly after birth. The polledness is highly favourable in modern cattle breeding systems but serious animal welfare issues urge for a solution in the production of hornless cattle other than dehorning. Although the dominant inhibition of horn morphogenesis was discovered more than 70 years ago, and the causative mutation was mapped almost 20 years ago, its molecular nature remained unknown. Here, we report allelic heterogeneity of the POLLED locus. First, we mapped the POLLED locus to a ∼381-kb interval in a multi-breed case-control design. Targeted re-sequencing of an enlarged candidate interval (547 kb) in 16 sires with known POLLED genotype did not detect a common allele associated with polled status. In eight sires of Alpine and Scottish origin (four polled versus four horned), we identified a single candidate mutation, a complex 202 bp insertion-deletion event that showed perfect association to the polled phenotype in various European cattle breeds, except Holstein-Friesian. The analysis of the same candidate interval in eight Holsteins identified five candidate variants which segregate as a 260 kb haplotype also perfectly associated with the POLLED gene without recombination or interference with the 202 bp insertion-deletion. We further identified bulls which are progeny tested as homozygous polled but bearing both, 202 bp insertion-deletion and Friesian haplotype. The distribution of genotypes of the two putative POLLED alleles in large semi-random sample (1,261 animals) supports the hypothesis of two independent mutations.
Ludwig-Maximilians-University Munich, Munich, Germany. ivica.medjugorac@gen.vetmed.uni-muenchen.de
Ivica
I
Medugorac
Doris
D
Seichter
Alexander
A
Graf
Ingolf
I
Russ
Helmut
H
Blum
Karl Heinrich
KH
Göpel
Sophie
S
Rothammer
Martin
M
Förster
Stefan
S
Krebs
D000483:Alleles; D000818:Animals; D016022:Case-Control Studies; D002417:Cattle; D002874:Chromosome Mapping; D005260:Female; D017353:Gene Deletion; D016678:Genome; D005838:Genotype; D006239:Haplotypes; D006720:Homozygote; D006801:Humans; D008297:Male; D051379:Mice; D008957:Models, Genetic; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D012756:Sheep; D013045:Species Specificity