Q: My daughter is 1 year and 8 months old and is a thalassaemia patient. I would like to know about Gene Therapy for this.

A:Thalassaemia are a group of genetic diseases caused by the production of abnormal haemoglobin, the red coloured protein present in red blood cells that transports oxygen in the body. Haemoglobin comprises two beta (b)-globin and two alpha (a)-globin chains, their production being governed by 2b and 4a genes respectively. In b-thalassaemia, the production of b-chain is abnormal while in a-thal it is the a-chain. When only one beta-globin gene is affected (thal minor or trait or carrier), it results in mild anaemia not requiring treatment but the involvement of both genes results in severe disease (thalassaemia major or intermedia) requiring regular treatment and follow-up from infancy. Currently, non-curative treatment modalities for b-thalassaemia major include: regular blood transfusion, iron chelation therapy (intravenous or oral), antioxidants and various inducers of fetal haemoglobin synthesis (hydroxyurea, erythropoietin, butyrates etc.). The only form of curative treatment at present is marrow transplant. Gene therapy promises to be a definitive cure because if a patients own bone marrow cells could be removed, a healthy beta-globin gene inserted and the cells returned to the patient, normal haemoglobin would be produced. Till date gene therapy has proved to be difficult. There are still problems with vectors (those carrying the normal gene into the cell), in getting normal levels of b-globin in red cell precursors and clinical safety. Current work continues in mouse models but human testing is still distant.