Michael Jackson -- Alpha Male?

Michael may be in desperate need of a lung transplant, according to Ian Halperin, author of a new M.J. bio.

Halperin claims Jacko suffers from a rare genetic disorder known as Alpha-1 antitrypsin deficiency, which has led to emphysema and gastrointestinal bleeding.

Halperin told In Touch Michael can barely speak and is nearly blind in his left eye.

We called MJ's reps -- nothing.