OMIA:001079-9940 : Yellow fat in Ovis aries (sheep)
Categories: Adipose tissue phene
Possibly relevant human trait(s) and/or gene(s) (MIM number): 611740 (gene)
Links to MONDO diseases: No links.
Mendelian trait/disorder: yes
Mode of inheritance: Autosomal recessive
Considered a defect: yes
Key variant known: yes
Year key variant first reported: 2010
Species-specific description: The presence of three xanthophylls (lutein, lutein-5-6-epoxide, and flavoxanthin) in sheep fat, presumably due to the inability to oxidise xanthophylls. Inherited as a single-locus autosomal recessive trait.
The paper by Niu et al. (2017) reports a genetically-modified organism (GMO)
Molecular basis: Vage and Boman (2010): "the coding region of the BCMO1 and the BCO2 gene were sequenced in yellow fat individuals and compared to the corresponding sequences from control animals with white fat. In the yellow fat individuals a nonsense mutation was found in BCO2 nucleotide position 196 (c.196C>T), introducing a stop codon in amino acid position 66."
Kent et al. (2021): "In spælsau we detected an aberration in BCO2 mRNA. Nanopore sequencing of genomic DNA revealed the insertion of a 7.9 kb endogenous Jaagsiekte Sheep Retrovirus (enJSRV) sequence in the first intron of the BCO2 gene. Close examination of its cDNA revealed that the BCO2 genes first exon was spliced together with enJSRV-sequence immediately downstream of a potential -AG splice acceptor site at enJSRV position 415. The hybrid protein product consists of 29 amino acids coded by the BCO2 exon 1, one amino acid coded by the junction sequence, followed by 28 amino acids arbitrary coded for by the enJSRV-sequence, before a translation stop codon is reached."
Gammelnorsk spaelsau, Norway (Sheep) (VBO_0016295),
Breeds in which the phene has been documented. For breeds in which a likely causal variant has been documented, see the variant table below
|Symbol||Description||Species||Chr||Location||OMIA gene details page||Other Links|
|BCO2||beta-carotene oxygenase 2||Ovis aries||15||NC_056068.1 (22198102..22268616)||BCO2||Homologene, Ensembl , NCBI gene|
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WARNING! Inclusion of a variant in this table does not automatically mean that it should be used for DNA testing. Anyone contemplating the use of any of these variants for DNA testing should examine critically the relevant evidence (especially in breeds other than the breed in which the variant was first described). If it is decided to proceed, the location and orientation of the variant sequence should be checked very carefully.
Since October 2021, OMIA includes a semiautomated lift-over pipeline to facilitate updates of genomic positions to a recent reference genome position. These changes to genomic positions are not always reflected in the ‘acknowledgements’ or ‘verbal description’ fields in this table.
|OMIA Variant ID||Breed(s)||Variant Phenotype||Gene||Allele||Type of Variant||Source of Genetic Variant||Reference Sequence||Chr.||g. or m.||c. or n.||p.||Verbal Description||EVA ID||Inferred EVA rsID||Year Published||PubMed ID(s)||Acknowledgements|
|1333||Spælsau||yellow fat||BCO2||insertion, gross (>20)||Naturally occurring variant||15||"insertion of a 7.9 kb endogenous Jaagsiekte Sheep Retrovirus (enJSRV) sequence in the first intron of the BCO2 gene" (Kent et al. 2021)||2021||34193038|
|320||Gammelnorsk spaelsau, Norway (Sheep)||Yellow fat||BCO2||nonsense (stop-gain)||Naturally occurring variant||Oar_rambouillet_v1.0||15||g.25024133C>T||c.196C>T||p.(Q66*)||Oar_v3.1 position is g.21947481C>T||rs1090867485||2010||20122251||Variant coordinates obtained from or confirmed by EBI's Some Effect Predictor (VEP) tool|
Cite this entry
Note: the references are listed in reverse chronological order (from the most recent year to the earliest year), and alphabetically by first author within a year.
|2021||Kent, M., Moser, M., Boman, I.A., Lindtveit, K., Árnyasi, M., Sundsaasen, K.K., Våge, D.I. :|
|Insertion of an endogenous Jaagsiekte sheep retrovirus element into the BCO2 - gene abolishes its function and leads to yellow discoloration of adipose tissue in Norwegian Spælsau (Ovis aries). BMC Genomics 22:492, 2021. Pubmed reference: 34193038 . DOI: 10.1186/s12864-021-07826-5.|
|2017||Niu, Y., Jin, M., Li, Y., Li, P., Zhou, J., Wang, X., Petersen, B., Huang, X., Kou, Q., Chen, Y. :|
|Biallelic β-carotene oxygenase 2 knockout results in yellow fat in sheep via CRISPR/Cas9. Anim Genet 48:242-244, 2017. Pubmed reference: 27862083 . DOI: 10.1111/age.12515.|
|2010||Vage, DI., Boman, IA. :|
|A nonsense mutation in the beta-carotene oxygenase 2 (BCO2) gene is tightly associated with accumulation of carotenoids in adipose tissue in sheep (Ovis aries). BMC Genet 11:10, 2010. Pubmed reference: 20122251 . DOI: 10.1186/1471-2156-11-10.|
|1985||Baker, R.L., Steine, T., Vabeno, A.W., Breines, D. :|
|The inheritance and incidence of yellow fat in Norwegian sheep Acta Agriculturae Scandinavica 35:389-397, 1985.|
|1972||Gedde-Dahl, T.W. :|
|[Reduction of the yellow fat incidence by different breeding plans for sheep]. Nord Vet Med 24:620-30, 1972. Pubmed reference: 4666502 .|
|1962||Hill, F. :|
|Xanthophyll pigmentation in sheep fat. Nature 194:865-6, 1962. Pubmed reference: 13907341 .|
|1934||Castle, W.E. :|
|Yellow fat in sheep Journal of Heredity 25:246-247, 1934.|
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