World Thalassemia day
World Thalassaemia day is observed every year on 8th of May to spread awareness amongst people about this deadly disease and to focus on prevention to avoid its transmission
The theme for this year is “Access to Safe & Effective Drugs in Thalassaemia”
The α-thalassemias involve the genes HBA1 and HBA2, inherited in a Mendelian recessive fashion. Two gene loci and so four alleles exist. It is also connected to the deletion of the 16p chromosome. α Thalassemias result in decreased alpha-globin production, therefore fewer alpha-globin chains are produced, resulting in an excess of β chains in adults and excess γ chains in newborns. The excess β chains form unstable tetramers (called hemoglobin H or HbH of 4 beta chains), which have abnormal oxygen dissociation curves.
Beta thalassemias are due to mutations in the HBB gene on chromosome 11, also inherited in an autosomal, recessive fashion. The severity of the disease depends on the nature of the mutation and on the presence of mutations in one or both alleles.
Mutated alleles are called β+ when partial function is conserved (either the protein has a reduced function, or it functions normally but is produced in reduced quantity) or βo, when no functioning protein is produced.
The situation of both alleles determines the clinical picture:
- β thalassemia major (Mediterranean anemia or Cooley anemia) is caused by a βo/βo No functional β chains are produced, and thus no hemoglobin A can be assembled. This is the most severe form of β-thalassemia;
- β thalassemia intermedia is caused by a β+/βoor β+/β+ In this form, some hemoglobin A is produced;
- β thalassemia minor is caused by a β/βoor β/β+ Only one of the two β globin alleles contains a mutation, so β chain production is not terribly compromised and patients may be relatively asymptomatic.
As well as alpha and beta chains present in hemoglobin, about 3% of adult hemoglobin is made of alpha and delta chains. Just as with beta thalassemia, mutations that affect the ability of this gene to produce delta chains can occur
Types of Thalassaemia :
- Thalassaemia trait/minor- Patient with mild anaemia
Individuals with thalassemia major usually present within the first two years of life with severe anemia, requiring regular red blood cell [RBC] transfusions. Findings in untreated individuals with thalassemia major are growth retardation, pallor, jaundice, poor musculature, hepatosplenomegaly, leg ulcers, development of masses from extramedullary hematopoiesis, and skeletal changes that result from expansion of the bone marrow. Peripheral blood smear shows, in addition to microcytosis and hypochromia, anisocytosis, poikilocytosis [spiculated tear drop and elongated cells], and nucleated red blood cells [i.e., erythroblasts]. Hb pattern [by cellulose acetate electrophoresis or high performance liquid chromatography [HPLC]] varies according to the type
- Thalassaemia intermediate- Patient may be treated with occassional or regular blood transfusion.
Patients have a moderate anemia and show a markedly heterogeneous hematological picture, ranging in severity from that of the betathalassemia carrier state to that of thalassemia major.
- Thalassaemia major – Pateint suffers from severe anaemia that may need regular transfusions in order to survive or a bone marrow transplant.
Carriers of beta-thalassemia are clinically asymptomatic. The characteristic hematological features are microcytosis (reduced red blood cell volume), hypochromia (reduced red blood cell Hb content) and increased HbA2 level.
Diagnosis can be done by
- Hematological Testing and
- Molecular Genetic Testing
- Hematological Testing can be done by
- Measuring Red blood cell indices
- Peripheral blood smear
Affected individuals demonstrate the red blood cell [RBC] morphologic changes of microcytosis, hypochromia, anisocytosis, poikilocytosis [spiculated tear-drop and elongated cells], and nucleated red blood cells [i.e., erythroblasts].
Qualitative and quantitative hemoglobin analysis [by cellulose acetate electrophoresis and DE-52 microchromatography or HPLC] identifies the amount and type of hemoglobin present.
- Molecular Genetic Testing
- Targeted mutation analysis.
The β-thalassemias can be caused by more than 200 different HBB gene mutations ; however, the prevalent molecular defects are limited in each at-risk population. The most commonly used methods are reverse dot blot analysis or primerspecific amplification ARMS PCR, real-time PCR or microarray technology
- Sequence analysis detects mutations in the HBB coding region and associated flanking regions. Sensitivity is 99%.
- Deletion/duplication analysis.
Deletions of variable extent of the HBB gene or of the beta-globin gene cluster that result in β- thalassemia or in the complex β-thalassemias called γδβ-thalassemia and δβ-thalassemia are rare causes of β-thalassemia. Some HBB alleles with deletion mutations can be common in certain ethnic groups [e.g., the 619-bp deletion in Asian Indians].
The American College of Obstetricians and Gynecologists recommends all people thinking of becoming pregnant be tested to see if they have thalassemia. Genetic counseling and genetic testing are recommended for families who carry a thalassemia trait.
A screening policy exists in Cyprus to reduce the rate of thalassemia, which, since the program’s implementation in the 1970s (which also includes prenatal screening and abortion), has reduced the number of children born with the disease from one of every 158 births to almost zero
In Iran as a premarital screening, the man’s red cell indices are checked first, if he has microcytosis (mean cell hemoglobin < 27 pg or mean red cell volume < 80 fl), the woman is tested. When both are microcytic, their hemoglobin A2 concentrations are measured. If both have a concentration above 3.5% (diagnostic of thalassemia trait) they are referred to the local designated health post for genetic counseling
Large scale awareness campaigns are being organized in India both by government and non-government organizations in favor of voluntary premarital screening to detect carriers of thalassemia and marriage between both carriers are strongly discouraged.
- Carrier detection
- Bone marrow transplant
Tips for Thalassaemia patients:
- Follow universal immunization to prevent exposure from infections
- Eating food low in iron is good as the patients undergo frequent blood transfusion
- Healthy diet and regular exercise also help to fight with this disease.
- Love and support of family and friends
Thalassemias are a major health problem, and approximately 1 in 14 of the population are carriers for one of the sub types. Over the past three decades, regular blood transfusions and iron chelation have dramatically improved the quality of life and transformed thalassemia from a rapidly fatal disease in early childhood to a chronic disease compatible with prolonged life. Today life expectancy varies between 25-55 years, depending on the compliance with medical treatment. Despite increased life expectancy, complications keep arising
There is an urgent need for making the people aware of this lethal malady. Health education is an important component of the preventive genetic programs. This requires proper health education and adequate sensitization to the individual, family or community to accept these preventive remedial measures. High cost of treatment, repeated blood transfusion and chelation therapy, and economic burden on family resources, all suggest that prevention is better than cure. Thus a joint venture of antenatal and inductive screening seems to be the most fruitful strategy for beta thalassemia in India. With improving environmental and socio-economic conditions, better public health care and medical facilities, effective malarial prophylaxis and better nutrition, children suffering from thalassemia and hemoglobinopathies can be better managed and rehabilitated in India
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