The European Commission granted a marketing authorisation valid throughout the European Union for Ataluren on 31 July 2014. It is used to treat patients aged 5 years and older with Duchenne muscular dystrophy who are able to walk. Duchenne muscular dystrophy can be caused by a number of genetic abnormalities. Ataluren is for use in patients whose disease is due to the presence of certain defects (called nonsense mutations) in the dystrophin gene which prematurely stop the production of a normal dystrophin protein, leading to a shortened dystrophin protein that does not function properly. Ataluren works in these patients by enabling the protein-making apparatus in cells to move past the defect, allowing the cells to produce a functional dystrophin protein. The main study involves 174 patients with Duchenne muscular dystrophy who were able to walk, where two doses of Ataluren (40 mg/kg daily and 80 mg/kg daily) were compared with placebo. The main measure of effectiveness was the change in the distance the patient could walk in six minutes after 48 weeks of treatment. Although an initial analysis of the results of all the data from the study did not show a significant difference in the distances patients in the Ataluren and placebo groups could walk, further analyses indicated that walking ability reduced to a lesser extent with 40 mg/kg daily Ataluren than with placebo: after 48 weeks of treatment patients receiving 40 mg/kg daily Ataluren could walk on average 31.3 metres more than those given placebo. This beneficial effect of the lower dose was also supported by improvements in other measures of effectiveness, including those directly linked to patients’ daily activities. No improvement was seen with the higher dose (80 mg/kg/day). The most common side effects with Ataluren are nausea (feeling sick), vomiting and headache. It must not be used at the same time as aminoglycosides when these are given by injection into a vein.