THALASSEMIA

Thalassemia is an inherited blood disorder in which the body is unable to make adequate hemoglobin.

Most of our physical characteristics are inherited through the genes we take from our parents; for example, the shape of our nose, the colour of our skin and eyes. We also inherit our hemoglobin (Hb) type from our parents, through the genes.

Hemoglobin is present in the red cells and is made from proteins. These proteins consist of alpha(α) and beta(β) chains. Normally 2 alpha and 2 beta chains are essential to form hemoglobin. Imbalances in these chains results in reduced red cell survival. The amount of beta and alpha chains a person makes is controlled by the hemoglobin gene they inherit from their parents

Normally red cells survive for 120 days but in Thalassemia red cell survival is reduced. Survival of Thalassemia patients depends upon repeated blood transfusion and costly medicines.

In our country beta Thalassemia is very common and the term Thalassemia denotes beta Thalassemia.

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KNOWLEDGE CENTER

Basic Inheritance

Thalassaemia is an inherited disorder of the red blood cells. These cells contain the hemoglobin molecule, which is responsible for binding oxygen from the air we breathe and carrying it to the tissues where energy is released.
In Thalassaemia one of the components of the hemoglobin molecule is inadequately produced or not produced at all. If there is lack of α- chain production then the result is known as α-thalassemia. If the component that is lacking is the β-chain, then the resulting condition is β- thalassemia.
The reason for the inadequate or non- production of these components is a change in the genetic code (mutation), in that part of the DNA, which is the template for the production of the protein. The mutation or altered gene cannot initiate the process, which hamper the production of necessary amount of protein.
Genes, sections of DNA responsible for a protein, are carried on chromosomes and each individual has a pair: one chromosome from each parent.
A mutation may exist on one chromosome of a pair, but not on the other. The protein produced by the one, “healthy”, and chromosome is enough to keep the individual well, even though his/her red cells are smaller than normal. Such an individual is known as a carrier (or heterozygote) who can only be detected by special blood tests. A carrier may give his/her offspring either the healthy chromosome or the one bearing the mutation.
Severe thalassaemia (Thalassemia Major) will result if a child inherits the abnormal (mutation bearing) chromosome from both parents. In other words both parents must be carriers if a major Thalassaemia disorder is present in the child. This situation is known as homozygous thalassemia.

Prevention of Thalassemia

Prevention is better than cure, Thalassemia is a completely preventable disorder.

It is suggested the following prevention policies can be adopted to reduce affected births by doing blood tests (HbA2 estimation) and save resources so that the best possible treatment can be made available for already existing cases.

Epidemiological studies: To determine local carrier rates, birth rates etc.
Health Education: All about Thalassaemia, the risk of having an affected child. Health Education is directed towards school pupils, the public and also health providers.
Population Screening: To identify carriers directed usually to the relatives of patients and couples before marriage.
Genetic Counseling: For couples at risk.
Prenatal diagnosis:
Testing the baby in the womb is called prenatal diagnosis and can be done as early as ten weeks of pregnancy in most cases Prenatal diagnosis enables one to know whether the unborn child is affected with disease or not. The laboratory procedures employed in prenatal testing are sensitive and rapid. Such prenatal testing must be accompanied with genetic and psychological counseling.

DNA prepared from a biopsy of chorionic villus can be obtained at 8-12 weeks gestation. The procedure is safe and low-risk.
DNA from amniotic fluid cells can be examined at 16 weeks.
Investigational attempts are ongoing to isolate fetal cells from maternal blood for DNA assay.
Pre-implantation diagnosis: The use of in-vitro fertilization (IVF) to either select healthy (non-carrier) ova for fertilization or after fertilization to select disease-free early embryos (blastocysts) for implantation in the uterus

Management and Treatment

Immunizations

Hepatitis B vaccine 4 doses, 2nd dose after 1 month & 3rd dose after 2 months and 4th after 1 year, then booster dose every 5th year.
Other immunization to be given as per universal immunization schedule.
Diet

Maintain a healthy diet. Your doctor may prescribe you a supplement of folic acid every day to help your body make new red blood cells.
A general well balanced diet is required. High protein Low iron and High calorie diet is generally advised for thalassemics
Patients on regular blood transfusions, should avoid taking vitamins or other supplements containing iron.
Activity
Although activity is unrestricted, patients may not be able to tolerate vigorous exercise or exertion.

Management guidelines

Fresh Saline washed packed red blood cell (not more than 6-7 days old) transfusions every 3 weeks to maintain post transfusion hemoglobin at 12.5 gm/dl.
Iron Chelation therapy after 15 blood transfusions, or serum ferritin > 1000gm/ml, in consultation with hematologist.
Check serum ferritin levels (IRON LEVELS) in body once in six months after starting chelation to adjust the dose of chelation drugs according to the ferritin levels and weight of the child.
Periodic medical checkup for serum ferritin level, liver function test & screening for hepatitis B and C, HIV, renal function tests, serum calcium & phosphorus level, dental checkup, cardiac checkup and endocrine function tests.
Bone marrow transplantation can cure the disease but in only 30% of siblings the Histocompatibility Linked Antigen (HLA) matched donor is available. Besides it is very expensive.
Drugs to improve hemoglobin, correct the defective hemoglobin are being investigated and hopefully we should get some answers. Also correction of the gene defect by gene therapy is being investigated.

Epidemiology of Thalassemia

There are an estimated 60-80 million people in the world who carry the beta thalassemia trait alone. This is a very rough estimate and the actual number of thalassemia Major patients is unknown due to the prevalence of thalassemia in less developed countries in the Middle East and Asia. Countries such as India, Pakistan and Iran are seeing a large increase of thalassemia patients due to lack of genetic counseling and screening. Most of them die in early life, often without a diagnosis or because of inadequate treatment. There is growing concern that thalassemia may become a very serious problem in the next 50 years, one that will burden the world’s blood bank supplies and the health system in general.

Carriers are found in all parts of the world:

People from the North Mediterranean (South Europe) coast have 1-19% carriers.
People of Arab origin have over 3% carriers. In Central Asia 4-10% and in South East Asia, the Indian subcontinent and China 1-40% carriers (the very high rates in this part of the world are due to HbE).
In the Americas, North Europe, Australia and South Africa the local population has very low carrier rates but Thalassaemia is still present because of the significant immigration from high prevalence areas.
In India:
It is estimated that there are 35 million carrier of Thalassemia i.e. 1 in 25. Around 10 – 15,000 babies with Haemoglobinopathies are born in India every year. Few of the ethnic groups like Sindhis, Gujarathis, Punjabis, Jains, Marwadis, etc are at high-risk communities for this diseaseEpid

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