<p>Genetic
disorder of the nervous system with tumors growing on the neural (nerve) cell
tissues. The tumors produce abnormalities such as skin changes and bone
deformities. Many affected have inherited the disorder but some cases arise
spontaneously but once the disease occurs spontaneously the genetic mutation is
passed on genetically. When tumors arise near vital structures such as the
cranial nerves of brainstem and are not operable, it can be life threatening.<br></p>