Two men are diagnosed with diabetes insipid us. One didn’t have the disorder until he suffered a…

Two men are diagnosed with diabetes insipid
us. One didn’t have the disorder until he suffered a stroke. The other had
withstood the condition all his life and it had never responded to exogenous
ADH despite the presence of normal ADH receptors. What might be the cause of
the diabetes insipid us in the two men?