von Hippel-Lindau disease 

Elongin is an elongation factor for RNA polymerase II.  Interestingly, elongin interacts not only with RNA polymerase II but also with the von Hippel-Lindau tumor suppressor protein.  Mutations in the gene for this protein that prevent its interaction with elongin result in a hereditary predisposition to various types of cancer.  The molecular basis for this predisposition is not yet understood.