(Adds background) Nov 22 (Reuters) - The U.S. health regulator...

(Adds background)

Nov 22 (Reuters) - The U.S. health regulator on Tuesday approved Australian drugmaker CSL Ltd (CSL) and partner Uniqure NV's QURE.O gene therapy for hemophilia B, potentially offering a long-term solution for patients with the blood clotting disorder.

The approval from the Food and Drug Administration makes the treatment, which will be branded Hemgenix, the first gene therapy for the rare inherited disorder that is usually treated by regular injections of clotting protein factor IX.

The companies expect the gene therapy to serve as a one-time shot to cut the rate of annual bleeding for hemophilia B patients, who represent about 15% of all patients with hemophilia.

The rare disorder is caused by a gene mutation that hampers the body's ability to make factor IX, and current treatments from companies such as Biogen BIIB.O and Pfizer PFE.N focus on regular infusions of the protein.