Genomewide association for a dominant pigmentation gene in sheep

Kijas, J. W.; Serrano, M.; McCulloch, R.; Li, Y.; Salces Ortiz, J.; Calvo, J. H.; Pérez-Guzmán, M. D.; Drögemüller, Cord; The International Sheep Genomics Consortium, ISGC (2013). Genomewide association for a dominant pigmentation gene in sheep. Journal of animal breeding and genetics, 130(6), pp. 468-475. Wiley-Blackwell 10.1111/jbg.12048

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Most published genomewide association studies (GWAS) in sheep have investigated recessively inherited monogenic traits. The objective here was to assess the feasibility of performing GWAS for a dominant trait for which the genetic basis was already known. A total of 42 Manchega and Rasa Aragonesa sheep that segregate solid black or white coat pigmentation were genotyped using the SNP50 BeadChip. Previous analysis in Manchegas demonstrated a complete association between the pigmentation trait and alleles of the MC1R gene, setting an a priori expectation for GWAS. Multiple methods were used to identify and quantify the strength of population substructure between black and white animals, before allelic association testing was performed for 49 034 SNPs. Following correction for substructure, GWAS identified the most strongly associated SNP (s26449) was also the closest to the MC1R gene. The finding was strongly supported by the permutation tree-based random forest (RF) analysis. Importantly, GWAS identified unlinked SNP with only slightly lower p-values than for s26449. Random forest analysis indicated these were false positives, suggesting interpretation based on both approaches was beneficial. The results indicate that a combined analytical approach can be successful in studies where a modest number of animals are available and substantial population stratification exists.

Item Type:

Journal Article (Original Article)


05 Veterinary Medicine > Research Foci > DermFocus
05 Veterinary Medicine > Department of Clinical Research and Veterinary Public Health (DCR-VPH) > Institute of Genetics
05 Veterinary Medicine > Department of Clinical Research and Veterinary Public Health (DCR-VPH)

UniBE Contributor:

Drögemüller, Cord


500 Science > 590 Animals (Zoology)
600 Technology > 630 Agriculture








Susanne Portner

Date Deposited:

01 May 2014 10:42

Last Modified:

27 Mar 2015 11:31

Publisher DOI:


PubMed ID:


Uncontrolled Keywords:

SNP50 chip, Sheep genomewide association studies, pigmentation


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