There are a number of interesting colour genes outside the major loci discusses elsewhere in the Genetics section. How well they are available for a mouse fancier, depends highly on one's location.

1. Silver si

The silver-gene causes silver ticking in the mouses coat. This means that the mouse's coat consists of different kinds of hairs: all white, all coloured, white tipped with colour and hairs with white and other colour in a striped manner. This gene is fully recessive. The amount of silvering and the depth of the colour, especially in the roots of the hairs varies quite a lot. Standardized silvered varieties are Silver Grey (Silver Black), Silver Brown and Silver Fawn. Common to all the silvered varieties is, that the silvering develops with age. In the nest the mouse looks like non-silvered, but before two months of age the mouse becomes apparently silvered.

1.1. A^y/* - si/si

Silvered dominant yellow mice are called Silver Fawns, regardless of their eye colour. These mice tend to have rather light base of hair, although this isn't desired in the standards. The ticking manifests as mentioned above, but as the mouse gets old, the ticking becomes less obvious. It has not been studied how BB, Bb or bb background affects the colour. Other genes present affect the colour as they normally do.

1.2. A/* -- si/si

Silvered Agouti mice have a lot of variation - some have lots of ticking, some look like regular Agouti mice - they can be told apart form regular Agouties by the light roots of hairs. However, this variety does not look like Silver Agouti, as the golden brown layer will not be affected by the silver gene. As the Silver Fawn, the silvered Agouti looses silvering with age. For a fancier, this genotype would be Silver Brown.

1.3. a^t/* -- si/si

When tanned varieties have also the silvered gene, the result is silvered tan. (When foxed - silvered foxes). These mice have the top colour silvered as in non-tanned variety and silvered belly colour as well (silvered like in Silver Fawn). 

1.4. a/a -- si/si

With a/a B/* si/si the mouse will be Silver Grey. These were formerly (in some standards still) recognized in three different shades - dark, medium and light. These shades mainly meant the colour of the roots of hairs. The belly of the Silver Grey mouse is slightly lighter than the top.

With a/a b^c/* si/si you have the Silver Chocolate.  The mouse should be rich golden brown in colour, with the ticking. In reality, the depth of the chocolate is reduced somewhat.

1.5. The Pearl mouse

This is somewhat arguable variety. The combination of a/a B/b si/si is an example where B does not fully dominate b and these mice are lighter in colour that a/a B/B si/si or a/a b/b si/si mice. The undercolour of these mice is almost pure white, leaving only the tips coloured dark. The effect is same with tanned varieties. Selecting for the lightest undercolour in silvered blacks and silvered chocolates should eventually lead to Pearls. However, this is rather difficult to breed