“Thalassemic carriers transform faulty genes to their child,” says Neeraj Gupta, Founder & CEO, Genes2Me, as he addresses the acute need for genetic screening of couples as an important part of family planning, on this World Thalassemia Day
Thalassemia is an inherited blood disorder in which the body makes an abnormal form of haemoglobin. Haemoglobin, a protein molecule in red blood cells, is useful in the transportation of oxygen in the human body.
The disorder results in excessive destruction of red blood cells, which leads to anaemia causing blood loss. Thalassemia is caused due to mutations in the DNA of the cells that make haemoglobin. The mutations associated with thalassemia remain in recessive condition in individuals. However, the recessive trait may pass on to the next progeny and the offspring may develop thalassemia major.
There are three main types of thalassemia:
• beta thalassemia, which includes the subtypes major and intermedia
• alpha thalassemia, which includes its subtypes
• thalassemia minor
Beta thalassemia occurs when your body is unable to produce beta globin. Two genes, one from each parent, are inherited to make beta globin. This type of thalassemia comes in two serious subtypes: thalassemia major or Cooley’s anaemia and thalassemia intermedia.
It is estimated that there are almost 3.6 to 3.9 crore carriers of β-thalassemia in India, and about 10000 to 15,000 babies with β-thalassemia major are born each year and around 150000 are living with Thalassemia major.
Who are the carriers?
People who inherit just one unusual gene are known as “carriers” having a ” recessive trait”. Carriers are usually healthy and are certainly not diseased but can pass the unusual gene on to their children.
However, when both parents are carriers, each time they are expecting a child there is:
• a one in four (25%) chance of the child not being affected – the baby will not have or carry the disease
• a one in four (25%) chance of inheriting both unusual haemoglobin genes and having the disease
• a two in four (50%) chance of inheriting one unusual haemoglobin gene and being a carrier
It is important that husbands of women detected to be carriers of β-thalassemia are also screened to identify the “high-risk couples”. Genetic counseling on β-thalassemia, genetic mutations, reproductive options, as well as the efficacy, accuracy and risks of fetal diagnosis procedures is then offered to all couples who are healthy carriers.
Thalassemia signs and symptoms may include:
• Pale or yellowish skin
• Facial bone deformities
• Slow growth
• Abdominal swelling
• Dark urine
Possible complications of Thalassemia include:
• Iron overload- People with thalassemia can get too much iron accumulated in their bodies due to frequent blood transfusions. Too much iron can result in damage to your heart, liver and endocrine system.
• Infection- People with thalassemia have an increased risk of infection.
Severe Thalassemia can result in
• Bone deformities- Bone marrow expansion can cause bones to become thin and brittle.
• Enlarged spleen (splenomegaly) – Thalassemia is often accompanied by the destruction of a large number of red blood cells. This causes the spleen to enlarge and work harder than normal.
• Slower growth- Anemia can cause a child’s growth to slow while thalassemia may cause a delay in puberty.
• Heart problems, such as congestive heart failure and abnormal heart rhythms (arrhythmias), may be associated with severe thalassemia.
Genetic Analysis Techniques
The molecular biology techniques employed for the diagnosis of β-thalassemia have changed over time with the development of new technologies.
Initially, the analysis was performed on fetal blood taken by placentocentesis. However, with current advancements, globin chain synthesis analysis by column chromatography on fetal blood is also practiced. Fetal DNA for analysis is obtained from either amniotic liquid or chorionic villi.
There are also a few diagnostic labs which offer specific test for Thalassaemia designed with the most common HBB gene mutations in the Indian population. The test is usually performed on specimen like peripheral blood, buccal swab, amniotic fluid, CVS or saliva.
Since India is a country with a low pre-emptive approach towards preventive healthcare, Thalassemia Carrier Screening is one of the most effective ways of ensuring that your child does not suffer from Thalassemia, a crippling lifelong blood disorder. In severe cases, the disease can be fatal, so the screening, as well as the diagnosis of this condition, is required to minimize the risk of occurrence.