Colour genes

Marking genes

Burmese & black eyed

These genes only show their effects on rats who already have a combination of the albino, Himalayan, and/or marten alleles on the c locus. Although the black eyed gene has been scientifically described, the Burmese gene hasn’t as of yet. The idea that these two genes are allelic is a fairly new idea, but it is backed by breeding results and explains many slightly odd breeding results over the years. The alleles at this locus are:

  • be – Recessive wild type (so “no effect”, c-locus rats have the appropriate colouring to their c-locus genetics).
  • BeBu – Burmese. Dominant to both other alleles. Overall body colour is darkened to a seal brown colour, yellow pigment is dulled, and eyes are black.
  • Be – Black eye. Dominant to wild type, recessive to Burmese. Eyes in all c-locus varieties are black, and the overall coat colour is slightly warmer/creamier.

With some of these varieties, it doesn’t matter if they are agouti or non-agouti based, they remain the same variety – for these, I have not included the A locus in the genotype below the photo, and you can assume that both A- or aa would give rats that look the same.

aa BeBuBeBu chch: Sable Burmese

aa BeBu- chch: Burmese

A- BeBu- chch: Wheaten Burmese

Be- chch: Black eyed Siamese

Be- cch: Black eyed Himalayan

Be- cc: Ivory