My 30 year old daughter, who has diabetes mellitus insipidus, also has optic atrophy but not deafness, and a pituitary tumor which causes the insipidus. If she would decide to have children, would they inherit this condition? Would they be born with it?

This is a very complex issue. There also seems to be some confusion in your terminology. There is diabetes mellitus and there is diabetes insipidus. There is no such things as “diabetes mellitus insipidus”, but, on rare occasions, someone can have both together, and this makes management tough.

As I think you are alluding to, there is a rare, inherited form where these conditions occur together. They can be associated with optic atrophy (which leads to blindness) and can be associated with nerve deafness. This combination is sometimes called Wolfram syndrome and sometimes is called DIDMOAD syndrome (this stands for Diabetes Insipidus, Diabetes Mellitus, Optic Atrophy, Deafness). There can be other associated problems too; one does not need to have all the components to still be diagnosed with this disorder.

It is inherited in such a way that both parents would need to be carriers, and if they were, there would be a 25% chance of their child having this. If a person has Wolfram syndrome, and they had children with someone who did not have Wolfram and who was not a carrier, then none of their children would have Wolfram syndrome, but we would expect all the children to be carriers. If a person with Wolfram syndrome has children with someone who was a carrier, then we’d expect 50% of the children to be carriers and 50% to develop Wolfram. If a person with Wolfram syndrome has children with another person with Wolfram syndrome, we’d expect all the children to have Wolfram syndrome.

These are issues that should be addressed with a clinical geneticist. Large academic medical centers and medical schools can guide you to a clinical geneticist or genetic counselor.

DS