mice genetics

Question
what would happen if a breed a albino mouse to a colored fancy mouse (black/white, or tan/white)

Answer
Hi Anne,

Albino is a dilution gene - a mouse must have two copies of a recessive gene called "c" (lower case) in order to be albino.  They still have all the other normal color variants, but because of that pair of recessive genes, nothing can show through.

Therefore, when you breed an albino to another mouse that is NOT albino, those hidden genes show through in the offspring (who will all have only ONE copy of the recessive albinism gene - written as C/c, one non-albino gene and one albino gene).  There's not much point to doing this if you don't know what the albino mouse is carrying underneath unless you just really have to know what the albino mouse is carrying.  In fact, doing so without a specific reason to breed them is kind of frowned upon because it means the offspring will carry around a surprise, hidden albino gene that could mess up someone's breeding further down the road.  It's a good idea to keep very complete records on any genetics you can deduce (for instance, that those offspring "carry" an albino gene) on all of your mice and offspring.

When you mention black/white and tan/white, do you mean they are spotted?  A spotted mouse is one that has one of a few possible white spotting genes.  The usual one is "s," with the recessive gene causing spotting when paired with another s.  This is separate from the color genes in that it doesn't change the color of pigmented hairs, but instead wipes out color from certain areas of the body.  An albino mouse MAY or may NOT carry spotting.  To be a solid color a mouse needs at least one dominant S (capital = not spotted), to be spotted it must have one recessive s (lower case = spotted) from each parent.

Genetics is a big, exciting puzzle and there are a lot of factors to explain.  The short answer is "it's impossible to know without pedigrees," but I would HIGHLY encourage you to please visit this site for a complete guide to mouse genetics, with pictures and everything:

http://www.hiiret.fi/eng/breeding/genetics/index.html

I still refer to this site myself, but it's written so that anyone with any level of expertise can understand it.  It's where I learned my stuff!  Please do check it out before you make any more pairs - it will save you a lot of time when it comes to breeding.  For the record, this is the same website that has amazing help for care, husbandry, and breeding so definitely check it out!

-Tam