 The most common side effect is pyrexia (fever).Serious side effects may include effects linked to autoimmunity (when the immune system attacks the body's own cells) such as hemolytic anemia (low red blood cell counts due to their too rapid breakdown), aplastic anemia (low blood cell counts due to damaged bone marrow), hepatitis (liver inflammation), thrombocytopenia (low blood platelet count) and Guillain-Barré syndrome (damage to nerves that can result in pain, numbness, muscle weakness and difficulty walking).The treatment was developed at San Raffaele Telethon Institute for Gene Therapy and developed by GlaxoSmithKline (GSK) through a 2010 collaboration with Fondazione Telethon and Ospedale San Raffaele.