UPDATE 1-Alnylam's rare genetic disorder drug gets early U.S. approval

Alnylam Pharmaceuticals Inc on Wednesday received an early U.S. approval for its gene silencing drug to treat patients with a rare genetic disorder that can cause severe pain.The drug, Givlaari, uses a mechanism known as RNA interference to target and "silence" specific genetic material, blocking the production of the protein that causes the disease called acute hepatic porphyria.