New diagnostic test for sickle cell disease could become available soon
Scientists at Oxford and Cambridge Universities have discovered a new technique for diagnosing sickle cell disease, which would be easier to use and would be cheaper than existing methods. The research funded by leading charity Action Medical Research could result in a new test for sickle cell which would be significant as an alternative simple diagnostic, test for this condition. The test’s probable low cost and ease of use means that it could be used in developing countries.
Sickle cell disease is an inherited disorder that affects red blood cells. Red blood cells contain haemoglobin, the substance that helps red blood cells carry oxygen around the body. Each year about 300 000 infants are born with major haemoglobin disorders – including more than 200 000 cases of sickle cell anaemia in Africa . The condition affects about 10 000 people in the UK. Normal red blood cells contain Haemoglobin A which keeps them flexible, disc shaped and able to squeeze through tiny blood vessels. Haemoglobin S and C are abnormal types of haemoglobin. The red blood cells of people with sickle cell conditions contain Haemoglobin S which causes the blood cell to shrink. This results in the blood cells becoming stiff, distorted in shape, similar to a ‘sickle’ resulting in difficulty passing through the body’s small blood vessels. Sickle cells can stick to the blood vessels, blocking the flow of blood resulting in pain, mainly in the arms, legs, chest and abdomen and damage to the organs of the body including the lung, brain and kidneys. In addition sickle cells are destroyed quickly in the blood compared to normal red blood cells, resulting in anaemia.
A severe attack, known as a sickle cell crisis, causes pain because blood vessels can become blocked, which can lead to damage to organs in the body. Sickle cell anaemia is the most common cause of stroke in children. Frequent episodes of crisis, infections and organ damage reduce the quality of life of people with sickle cell disease. The average life expectancy with sickle cell disease is about 50.
The research team has discovered that deoxygenated sickle cells, unlike normal red blood cells, when placed in certain solutions allow sugars into the cell. This causes the cells to break open and release the haemoglobin, which could be used to indicate the presence of sickle cells, and a diagnostic test could be developed based on this.
Commenting Dr Yolande Harley, Deputy Director of Research at Action Medical Research: “Sickle cell disease is a very debilitating condition and a test that could improve diagnosis in developing countries would be an important advance that could have worldwide benefits.”
The research teams, are led by Professor Clive Ellory, Professor of Physiology, Oxford University, and Dr John Gibson, Reader in Pathophysiology, Cambridge University. They comment: “This research could have a significant impact on people with sickle cell in two ways: Our findings could result in a simple test to diagnose sickle cell based on whether red blood cells absorb sugars. This would be particularly important in pregnancy as mothers with sickle cell tend to be anaemic and have more sickling crises, which could be life-threatening to the baby. As the test is simple and likely to be inexpensive, it could be used to diagnose the condition in developing countries that don’t have the resources for expensive tests. Early detection in babies could help families be better prepared to manage the condition.”
It is thought that the abnormality in the S haemoglobin leads to changes in the permeability of the red blood cell membrane causing the cells to shrink. Research from the teams at Oxford and Cambridge has led to a greater understanding of the mechanisms and pathways by which sickle cells lose salts and water and become dehydrated. This research could lead to the development of drugs to block this pathway and hopefully reduce both the number of sickle cells in the blood and crises. It is this abnormal permeability which also forms the basis of the new diagnostic test.
For further information please contact:
Prof Clive Ellory, Department of Physiology, Anatomy and Genetics, Oxford University 01865 272436
Dr John Gibson, Department of Veterinary Medicine, Cambridge University 01223 337638
Tola Awogbamiye at Action Medical Research
Tel: 01403 327 493
1 World Health Organisation. Sickle Cell Anaemia – report by the secretariat A59/9. April 2006
2 de Montalembert M; Management of sickle cell disease. BMJ. 2008 Sep 8;337:a1397. doi: 10.1136/bmj.a1397.
3 Switzer JA, Hess DC, Nichols FT, Adams RJ. Pathophysiology and treatment of stroke in sickle-cell disease: present and future. Lancet Neurol. 2006 Jun;5(6):501-12.
4 Claster S, Vichinsky EP; Managing sickle cell disease BMJ 2003;327:1151-1155.
Further information about the research is available from: Ellory JC, Sequeira R, Constantine A. et al. Non-electrolyte permeability of deoxygenated sickle cells compared. Blood Cells Mol Dis. 2008;41(1):44-9.
Notes to editors:
Action Medical Research is a leading, national medical research charity. For nearly 60 years we have been instrumental in significant medical breakthroughs including the development of the UK polio vaccine and ultrasound scanning in pregnancy. Our research helps babies and children affected by disease and disability. We are currently funding research into serious diseases and conditions, including meningitis, pneumonia, cerebral palsy and inflammatory bowel disease.
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