Michael Jackson has been left half-blind and needing a lung transplant by a potentially deadly genetic disease, according to the singer's biographer Ian Halperin.

The fallen King Of Pop – who has looked frail during his increasingly rare public appearances – is said to be suffering from an inherited condition called A1AD (alpha-1 anti-trypsin deficiency) in which sufferers lack a protein responsible for protecting the lungs.

Halperin - who has also written an 'expose' of Britney Spears - said, ““He needs a lung transplant, but may be too weak to go through with it. He also has emphysema and chronic gastrointestinal bleeding, which his doctors have had a lot of trouble stopping.

“It’s the bleeding that’s the most problematic part. It could kill him.”

“For years Michael has been working with his doctors to make sure it doesn’t progress. He has been on many medications that have stabilised him.”

Michael's brother Jermaine confirmed that the star is sick, saying: “He’s not doing so well right now. This isn’t a good time.”