Mono-morphia
From Tardis Wiki, the free Doctor Who reference
Mono-morphia was a disease that affected Whifferdills' ability to change shape. It prevented any shape changing until the disease wore off, leaving the sufferer in the form it had when it contracted the disease. The disease vector was unknown and the length of suffering varied enormously. Frobisher was affected by mono-morphia and was stuck in the form of a penguin. (COMIC: Genesis!) The disease wore off partially before returning to re-affect his abilities. (COMIC: Changes, Profits of Doom!)