How did elephant man get like he was?

Joseph Merrick, aka the Elephant Man, suffered from a rare condition which, for many years, was undetermined. Recent studies have suggested that Merrick suffered either from neurofibromatosis type I, a genetic disorder also known as von Recklinghausen's disease, or Proteus syndrome, which affects tissue other than nerves - or even a combination of the two. Either way, the condition/s caused abnormal masses of flesh to develop on his face and body.