What are the chances of a person with this disease passing the disease to their offspring?

The chances depend on whether their spouse is a carrier, has the disease, or is completely free of the mutated genes. If the the spouse is a carrier, than it's xx,Xx, and they have a 50% chance of passing it on, and all of the unaffected children will be carriers. If the spouse has the disease, than it's xx,xx and all of their children will have the disease, because there aren't any healthy genes present. If the spouse is free of the mutations, than it's xx,XX and none of the children will have the disease. They will all be carriers however.