Freeline Therapeutics Holdings plc, a clinical-stage biotechnology company, develops transformative adeno-associated virus (AAV) vector-mediated gene therapies. It develops FLT180a for the treatment of hemophilia B.; FLT201 for the treatment of Type 1 Gaucher disease; and FLT190 for the treatment of Fabry disease. in addition, it has research programs for systemic gene therapy. The company was founded in 2015 and is headquartered in Stevenage, the United Kingdom.