The UK Medicines and Healthcare products Regulatory Agency has extended the authorisation of Casgevy (exagamglogene autotemcel) so that children aged five and over with severe sickle-cell disease and transfusion-dependent β-thalassemia can receive the gene-editing treatment. The therapy had previously been authorised in the UK for patients aged 12 and over with these inherited blood disorders. The marketing authorisation extension was granted on 29 October 2026 to Vertex Pharmaceuticals (Europe) Ltd, according to the regulator.

Both conditions stem from errors in the genes for haemoglobin, the protein red blood cells use to carry oxygen. Severe sickle-cell disease can cause attacks of very severe pain, serious and life-threatening infections and anaemia, while β-thalassemia can lead to severe anaemia; patients often need a blood transfusion every 3 to 5 weeks plus injections and medicines throughout their lives. Casgevy edits a faulty gene in bone marrow stem cells so the body produces functioning haemoglobin. Cells are collected from the patient, edited in a laboratory and infused back after conditioning treatment.

Julian Beach, the MHRA's Executive Director Operations, said the approval was based on careful assessment of evidence on the treatment's safety, quality and effectiveness, and that the regulator will continue to monitor it closely. Listed side effects include nausea, fatigue, fever and increased risk of infection. The MHRA notes that approximately 15,000 people in the UK have sickle cell disorder.