Other Rabbit Genetics Topics
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Yellow Fat Locus (Y)
This is a recessive mutation on the BCO2 gene (Strychalski et al., 2019). Rabbits with two copies of the recessive y mutation develop yellow fat. The loss of function mutation causes the gene to be unable to break down non-provitamin A carotenoids, so carotenoids (which have a yellow-orange color) are stored in the fat, giving said fat a yellow color. Rabbits with this mutation hold higher amounts of lutein, β-carotene, retinol (a major form of vitamin A), and α-tocopherol (a form of Vitamin E) in perirenal fat, as well as more lutein in the liver. Diets rich in carotenoids make the pigment more intense.
Figure to the left shows a rabbit carcass without the yellow fat mutation on the left, and the rabbit carcass on the right shows one with the yellow fat mutation.