April 26 (Reuters) - The U.S. Food and Drug

Administration approved Pfizer's ( PFE ) gene therapy for

hemophilia B on Friday, the second such therapy for the rare

bleeding disorder that typically requires regular infusions of a

blood-clotting protein.

People with hemophilia have a fault in a gene that regulates

production of proteins called clotting factors, which can cause

spontaneous as well as severe bleeding following injuries or

surgery. It predominately affects males.