The notorious "elephant man" may have suffered from two rare disorders, according to scientists.
A computer image of how Merrick may have looked
They believe Joseph Merrick, who lived in Britain more than 100 years ago, could have suffered from type 1 neurofibromatosis (NF1) and Proteus syndrome.
They believe both conditions may have combined to trigger his severe physical deformities.
Their claim, which is featured in a new series on the Discovery Health channel, follows DNA tests on the man's hair and bones.
Merrick, who was born in Leicester in 1862, showed signs of deformity from the age of five.
By the time he was a teenager, he was completely deformed and had been rejected by his community and his own parents.
He was a member of a travelling circus and became widely known for his role as a fairground freak.
How Merrick may have looked without his affliction
In his mid-20s, he met a surgeon who arranged for him to be admitted to the Royal London Hospital, where he died at the age of 27.
The cause of his severe deformities has baffled doctors for more than a century.
A team of international scientists sought to resolve the problem by carrying out DNA tests on his remains.
They obtained samples of his hair and bone. Tests suggested he may have suffered from NF1 or Proteus syndrome, or maybe even both.
NF1 is a rare genetic disorder. It can cause tumours to grow in several parts of the body and can cause enlarged deformations of bones.
Proteus syndrome is present at birth and can cause overgrowth in different parts of the head, including the head and limbs.
However, the tests were not conclusive.
"He definitely had Proteus syndrome," Dr Charis Eng, a cancer geneticist at Ohio State University told BBC News Online.
"Whether he had NF1, we cannot tell. Photographs and his death mask would suggest he had some of the features. I don't know."
The scientists have kept the DNA samples and may carry out further tests in the future.
The TV series follows scientists in their efforts to try to find out what caused Merrick's severe deformities.
It also includes images of what Merrick would have looked like had he not been burdened by disease.