Our high school genetics chapter has some extra information about L.Cuenot. It only covered his research, and the fact that mice homozygous for yellow coat color would die before birth. It was an example of a lethal allele.
We have learned about sickle cell anemia, thalassemia, and hemophilia. All of them had a specific reason/mechanism which caused damage. For example, it's not the shape of the red blood cell in itself which is problematic, it is the fact that it can't carry enough oxygen. Therefore the cell will die off much quicker than normal cells.
I asked few of the biology teachers why the yellow coat color was lethal, but they couldn't provide any answer.
My question is, what causes the mice to die before birth?
Links to relevant articles or excerpts from them are highly appreciated.