COLOUR GENETICS - C locus

The C gene is especially interesting. In many animal species it is called ALBINO. Others refer to it at the CHINCHILLA gene or the CONCENTRATION gene. The C gene appears to act like a filter controlling the development and expression of the light coat pigment. The C gene is considered to mainly affect light pigment, though it may influence dark coat colour to some extent and is perhaps partially responsible for soft black, dusty darks and the like. The dominant
[ CC ] does not filter at all, and allows a deep full intensity coat to develop. Filtered red develops less colour pigment and so shows as gold, apricot, champagne, cream etc. This may be modified further by enhancement/muting genes to make innumerable variations. Order of dominance is [ C ] > [ c ^ch ] > [ c ^e ] > [ c ]. Darker and lighter shades of each may blend into each other. For instance [ C c ^e ] and [ c ^ch c ^ch ] can be indistinguishable.

There is still much which is not yet known about colour genetics. There may be many more genes at play than are currently known or theorized about. Genetics in all species is an evolving field, there is always more to be discovered and to be learned. There has been some recent discoveries in the chinchilla gene that suggest it may not work exactly as we had theorized previously.

Note - Albino in mammals is the most extreme expression of this gene, fully recessive [cc] that prevents any colour from being made at all in coat, eyes and nose, and results in an albino animal with pink nose and red eyes (like an albino rat). Albino does not seem to appear to occur in dogs normally (though is possible) and is only mentioned here for interest sake. The white found in Havanese may actually be extremely filtered [ c ^e c ^e ] off-white. He may have some very watered colour. A white Havanese has eye and nose pigment, he is not albino.