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Sickle-cell disease and other haemoglobin disorders
WHAT ARE HAEMOGLOBIN DISORDERS?
Haemoglobin disorders are inherited blood diseases that affect how oxygen is carried in the body. Haemoglobin disorders fall into two main categories: sickle-cell disease and thalassaemias.
FACTS ABOUT HAEMOGLOBIN DISORDERS
WHAT CAUSES HAEMOGLOBIN DISORDERS?
Haemoglobin disorders are inherited from parents in much the same way as blood type, hair color and texture, eye colour and other physical traits.
Sickle-cell disease and thalaessemias can occur only when both parents have trait genes for the particular condition. A child who inherits two of the same trait genes - one from each parent - will be born with the disease. However this is not inevitable: a child of two carriers has only a 25% chance of receiving two trait genes and developing the disease, and a 50% chance of being a carrier. Most carriers lead completely normal, healthy lives.
HOW CAN HAEMOGLOBIN DISORDERS BE REDUCED?
Haemoglobin disorders can be effectively reduced through a strategic balance of disease management and prevention programmes.
Sickle-cell disease cannot be cured; however the condition can be managed by:
Thalassaemias require regular blood transfusions to maintain a healthy supply of haemoglobin and sustain life. As a result of multiple transfusions, organs become severely overloaded with iron and secondary treatment is needed to manage this condition. Thalassaemias can be cured by successful bone-marrow transplantation, however this procedure is expensive and not readily available in most settings.
The most cost-effective strategy for reducing the burden of haemoglobin disorders is to complement disease management with prevention programmes. Inexpensive and reliable blood tests can identify couples at risk for having affected children. This genetic screening is especially opportune before marriage or pregnancy, allowing couples to discuss the health of their family. Subsequent genetic counselling informs trait carriers of risks that may be passed along to their children and the treatment needed, if affected by a haemoglobin disorder. Prenatal screening of genetic diseases raises specific ethical, legal and social issues that require appropriate consideration.
WHO'S ACTIVITIES FOR PREVENTING AND CONTROLLING HAEMOGLOBIN DISORDERS
The governing bodies of the World Health Organization have adopted two resolutions on haemoglobin disorders. The resolution on Sickle-Cell Disease from the 59th World Health Assembly in May 2006 and the Resolution on Thalassaemia from the 118th meeting of the WHO Executive Board call upon affected countries and the secretariat of WHO to strengthen their response to these conditions.
Specifically, WHO will:
WHO'S STRATEGY FOR PREVENTION AND CONTROL OF CHRONIC DISEASES
WHO’s work on haemoglobin disorders is integrated into the overall WHO chronic disease prevention and control framework of the Department of Chronic Disease and Health Promotion. The strategic objectives of the Department are to raise awareness about the global epidemic of chronic diseases; create healthy environments, especially for poor and disadvantaged populations; slow and reverse trends in common chronic disease risk factors such as unhealthy diet and physical inactivity; and prevent premature deaths and avoidable disability due to major chronic diseases.
Sources: US Department of Health; The World Health Organization