Blood gene clue to sickle cell therapy
27 September 2007
Medical Research Council funded scientists working at King’s College London have identified a gene that accounts for variation in peoples’ levels of fetal haemoglobin (HbF) in a discovery that could help in treatment of people with sickle cell anaemia. Hbf is the version of the protein that transports oxygen while a foetus is developing in the womb. The gene, called BCL11A, was discovered using an alternative research technique that focuses on the genetics of a small number of people who have extreme levels of fetal haemoglobin rather than a large number who have varying levels.
Most HbF has been replaced by the adult version in infants by the time that they are six months old but a small amount is left over that remains in the body throughout adult life. However, it is already known that high levels of HbF have a beneficial effect on the blood disorders sickle cell disease and beta thalassaemia.
Lead researcher Professor Swee Lay Thein of King’s College London School of Medicine and King’s College Hospital explains the significance of this discovery:
‘‘In patients who have sickle cell disease, the higher their level of foetal haemoglobin, the less severe their symptoms. Internationally, scientists are working on ways to increase levels of this kind of haemoglobin to reduce the severity of sickle cell disease in individuals. We have identified a gene that should provide us with further information about how foetal haemoglobin production is regulated in the body and in turn provide insights into ways to boost levels to treat sickle cell disease.’’
To make the discovery, Professor Thein collaborated with Professor Mark Lathrop of Centre National de Génotypage in Evry, France. They also found that the BCL11A gene does not work alone. There are two other genes involved in HbF production, together the three genes account for up to 50% of the variation of HbF levels in adults.
Professor Thein and her colleagues have plans to produce a diagnostic test based on the three genes that will predict a person’s ability to generate the foetal version of haemoglobin throughout their life. The team at Kings College London have filed two patent applications for the test, known as a DNA chip diagnostic because it analyses a person’s DNA to identify whether they carry the genetic variants, to aid in commercialisation of the technology. The results of such a test would be a useful guide for genetic counselling for people who have sickle cell disease or beta thalassemia.
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