Homozygous Roan Lethal?
So I'm currently taking a genetics class. First day was today and she put up some extra credit already for us to do. Lucky for me it's all about horse genetics YAY! I might need more help when I start into it more. She gives us pictures and we're suppose to say what it's full genetic coding is...
Anyway...I'm reading the powerpoint and according to it: "All roan horses are heterozygous Rnrn as homozygous RnRn is lethal".
Is this true? I've actually never heard of this. Does it work the same way as lethal white? If I thought about it correctly this would mean breeding two roans would have a 25% chance of lethal. Am I totally crazy or is this incorrect?