FDA has approved CSL Behring’s (ASX: CSL) Hemgenix (etranacogene dezaparvovec), an adenovirus-associated virus–based gene therapy for adults with hemophilia B. The price tag for the gene therapy — the first for hemophilia B — is $3.5 million. The drug is administered as a single infusion. Hemophilia B is a genetic bleeding disorder caused by missing or…