December 15, 2010, 9:24 pm
* Thalassaemia is a genetically transmitted disease
* It affects the haemoglobin component of red blood cells and leads to early destruction of the affected cells.
* there is a wide spectrum of presentations depending on the type of involvement of the genes
* Severely affected children need regular blood transfusions.
* Iron overloading is a major problem that leads to life-threatening complications
* Newer modalities of treatment hold a lot of promise.
* the disease can be prevented by detecting carriers of the genes involved.
The red blood cells in the normal human being perform the important function of transporting and providing oxygen to the tissues of the body. for this important function to be performed the normal haemoglobin plays a crucial role and the normal amount of haemoglobin in the blood is scrupulously regulated in the human body. the normal red cells have a finite life span of around 120 days and there is a dynamic process of old red cells being destroyed in the body followed by replenishment of the destroyed red cells by new cells formed in the bone marrow. there is a very specific chemical structure of normal human haemoglobin and any alteration of this structure makes the cells more susceptible for destruction and in such instances they are destroyed well before their normal life span of 120 days.
Thalassaemias are inherited genetic disorders that involve decreased and defective production of haemoglobin which is the molecule found inside all red blood cells which play a part in the transportation of oxygen throughout the body. Normal human hemoglobin contains two different kinds of protein chains named alpha and beta chains. there are two types of thalassaemia, alpha-thalassaemia and beta-thalassaemia. Their names describe which part of the hemoglobin molecule is affected, namely the alpha or the beta chain. any deficiency in these chains causes abnormalities in the formation, size and shape of the red blood cells. This process makes these cells to be more susceptible to destruction by the normal regulatory processes of the body. As a result, people with thalassaemia often have a reduced number of red cells in the bloodstream which leads to anaemia which can affect the transportation of oxygen to body tissues. In addition, thalassemia can cause the red cells to be smaller than normal or drop the haemoglobin content in them to below-normal levels. Depending on the type of thalassaemia and the degree to which they are affected, children with this disease may exhibit an array of the illness ranging from very mild inconsequential disease to a very severe life-threatening format. In other words, some only have mild anaemia with little or no effects while others require frequent serious medical treatment.
Thalassaemia is always inherited and passed on from parents to children through their genes. A child usually does not develop severe symptoms unless both parents carry a thalassaemia gene. these parents, who are reasonably normal to all intents and purposes, are known as "carriers" of the disease. if only one parent passes a gene for thalassaemia on to the child, then the child is said to have the thalassaemia trait. such a thalassemia trait will not develop into the full-blown disease and no medical treatment is usually necessary. many families have thalassaemia carriers, but the trait often goes undiagnosed because it produces none or very few symptoms. Frequently, thalassaemia is not diagnosed in a family until a baby is born with a severe form of the disease. at one time it was believed that the disease affected only people of Italian or Greek descent, but it is now known that many people with thalassaemia also come from or are descended from Africa, Malaysia, China and many parts of South East Asia. Because of a recent pattern of migration from Southeast Asia, there has been an increase in the past decade of thalassaemia in Europe and the USA.
Children with alpha-thalassaemia trait do not have thalassaemia disease. People normally have four genes for alpha globin, two inherited from each parent. if one or two of these four genes are affected, the child is said to have alpha-thalassemia trait. A specific blood test called a hemoglobin electrophoresis is used to screen for alpha-thalassaemia trait and can be done in infancy. often, results of the haemoglobin electrophoresis test are normal in people who have alpha-thalassaemia trait and a diagnosis of alpha-thalassaemia is made only after other conditions are ruled out and after the parents are screened. the disease can be harder to detect in older children and adults. those who have the alpha-thalassaemia trait usually have no significant health problems except mild anaemia which can cause slight fatigue. Alpha-thalassaemia trait is often mistaken for iron deficiency anaemia because the red cells appear small when viewed under a microscope. Other cases can cause more severe anaemia where three genes are affected. People with this form of alpha-thalassaemia may require occasional blood transfusions during times of physical stress, like fevers or other illnesses or when the anaemia is severe enough to cause symptoms such as fatigue. the most severe form of the disorder is called alpha-thalassaemia major. This type is extremely rare and women carrying fetuses with this form of thalassaemia have a high incidence of miscarriage because the fetuses cannot survive.
Beta-thalassaemia, the most common form of the disorder seen, is grouped into three categories such as beta-thalassemia minor (trait), intermedia, and major. A person who carries a beta-thalassemia gene has a 25 per cent or 1 in 4 chance of having a child with the disease if his or her partner also carries the trait. Beta-thalassaemia minor often goes undiagnosed because children with the condition have no real symptoms other than mild anaemia and small red blood cells. It is often suspected on routine blood tests such as a complete blood count and can be confirmed with a haemoglobin electrophoresis. No treatment is usually needed. As with alpha-thalassaemia trait, the anaemia associated with this condition may be misdiagnosed as an iron deficiency. Children with beta-thalassaemia intermedia have varying effects from the disease. Mild anaemia might be their only symptom or some might require regular blood transfusions. the most common complaint is fatigue or shortness of breath. Some of them also experience heart palpitations which is also due to the anaemia and mild jaundice which is caused by the destruction of abnormal red blood cells that result from the disease. the liver and spleen may be enlarged, which can feel uncomfortable for a child. Severe anaemia can also affect growth. another symptom of beta-thalassaemia intermedia can be bone abnormalities. Because the bone marrow is working overtime to make more red cells to counteract the anaemia, these children can experience enlargement of their cheekbones, foreheads, and other bones. Gallstones are a frequent complication because of abnormalities in bile production that involve the liver and the gallbladder. Some of them with beta thalassaemia intermedia may require a blood transfusion only occasionally. They will always have anaemia, but may not need transfusions except during illnesses, medical complications or later on during pregnancy. Other children with this form of the disease require regular blood transfusions. In them, low or falling haemoglobin levels greatly reduce the blood’s ability to carry oxygen to the body, resulting in extreme fatigue, poor growth, and facial abnormalities. Regular transfusions can help alleviate these problems. Beta-thalassaemia intermedia is often diagnosed in the first year of life. Doctors may be prompted to test for it when a child has chronic anaemia or a family history of the condition. As long as it is diagnosed while the child is still doing well and has not experienced any serious complications, it can be successfully treated and managed.
Beta-thalassaemia major, also called Cooley’s anemia, is a severe condition in which regular blood transfusions are necessary for the child to survive. although multiple lifelong transfusions save lives, they also cause a serious side effect. That is the overloading of iron in the bodies of thalassaemia patients. Over time, people with thalassaemia accumulate deposits of iron, especially in the liver, heart, and endocrine hormone-producing glands. the excessive iron deposits eventually can affect the normal functioning of these organs and in many cases, premature deaths are due to complications arising as a result of malfunctioning of these organs.
To minimize iron deposits, children need to undergo chelation or iron-removing therapy. This can be done by taking daily medication by mouth or by subcutaneous or intravenous administration. Daily chelation therapy when given regularly has been proven to prevent liver and heart damage from iron overload, allow for normal growth and sexual development and increase the life span. Iron concentrations are monitored every few months. Sometimes liver biopsies are needed to get a more accurate picture of the bodyiron load. Children on regular transfusions are monitored closely for iron levels and complications of iron overload even when they are on the chelation medications. Other risks associated with chronic blood transfusions for thalassemia major include blood-borne diseases like hepatitis B and C. Blood banks screen for such infections, in addition to rarer infections such as HIV. In addition, those who have many transfusions can develop allergic reactions that can prevent further transfusions and cause serious illnesses.
For children and teens with thalassemia, adolescence can be a difficult time, particularly because of the amount of time required for transfusions and chelation therapy. Over the last few decades, some severely affected children in other countries have successfully undergone bone marrow transplants to treat thalassaemia major. It is however considered only in cases of very severely disabling thalassaemia disease. there is considerable risk to bone marrow transplants as the procedure involves the destruction of all of the blood-forming cells in the bone marrow and repopulating the marrow space with donor cells that must match perfectly with the tissues of the patient. the closest match is usually from a sibling. the procedure is usually undertaken in children younger than 16 years of age who have no existing evidence of liver scarring or serious liver disease. Results have been encouraging so far, with disease-free survival in many patients. Blood-forming stem cells taken from umbilical cord blood have also been successfully transplanted and research using this technique is expected to increase in the future. currently bone marrow transplantation treatment and stem cell transplant techniques are the only known "cure" for the disease.
In the Sri Lankan scenario, thalassaemia, especially the severe forms of the disease cause many problems for the health service and the families of affected children. there are areas in the country such as the North Central province, Central province, Uva province and the Southern province where there are considerable numbers of affected children. the prevalence of the disease is increased in communities where there is inter-marriage, marriage between close relatives and consanguinity. This is simply because of the fact that the chance of two carriers marrying is that much increased in these situations. With time, many carriers are produced in the community and they may not even be related. In such a scenario, even unrelated marriages could produce siblings with the severe form of the disease.
The National Health Service of Sri Lanka spends a very large amount of money for regular medical treatment, follow-up, blood transfusions and iron chelation therapy for these children. Some of these patients are from very poor communities in very remote areas of the country. the necessity for regular travelling for medical treatment and follow-up leads to many problems for these families most of whom have major social and economic problems. They go through untold suffering in their quest to keep these unfortunate children alive and relatively healthy. the resources of the hospitals in these areas are also taxed to the maximum in trying to cope with the problem which has become a never-ending type of predicament.
The authorities have now established a National Thalassaemia Centre in Kurunegala and also provided the North Colombo Teaching Hospital at Ragama with several facilities for ultra-modern testing for these diseases. the ultimate aim is to detect carriers and prevent marriages between them. This will be a very potent arm in preventing the severe form of the disease and in that context thalassaemia, at least the severe form of it, is one of the eminently preventable diseases. In addition, continuing research into the disease has produced several potent chelating agents that can prevent the long term consequences of iron overload for those requiring regular multiple blood transfusions. In time to come even bone marrow and stem cell transplantation may become real possibilities in the country.
As frightening as thalassaemias can be, the future outlook is somewhat encouraging. In the past few decades, new techniques and advanced forms of therapies have greatly improved the quality of life and life expectancy for children who have these diseases. Modern methods of screening for carrier states hold a golden promise and a window of great opportunities for prevention of the more severely affected cases in the future. one hopes that, even in our country, we would be able to make life that much better for these unfortunate affected families and await the light at the end of the tunnel as a result of effective prevention of the disease in the future.
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