The management and treatment of thalassemia patients depend on the extent of severity
Thalassemia is an inherited genetic disorder of the blood that results from a reduced synthesis of a protein called hemoglobin, an important part of red blood cells. Hemoglobin serves as the oxygen-carrying vehicle of the red blood cells and are made up of two different proteins, an alpha, and a beta.
Optimum oxygen is a sort of food that body cells use to function properly. Due to defective (genetic mutation or a deletion of gene fragment) hemoglobin, there is a scarcity of enough healthy red blood cells in the body, leading to suboptimal oxygen delivery to various cells. This causes anemia that commences in early childhood and may cause a person to feel tired, weak, or short of breath, faster heart rate and pale skin colour. It affects 1 per 100,000 newborns per year on average in the world, with a higher incidence in Mediterranean countries, China, India and Southeast Asia.
Thalassemias are basically classified into two main types, alpha and beta thalassemia. Alpha thalassemia is caused by deletion of alpha globin gene which results in decreased or complete absence of alpha-globin chains while Beta thalassemia results from point mutations in the beta globin gene. The severity of thalassemia is noted by words like trait, carrier, intermedia, or major.
A person who has thalassemia trait or carrier (single mutation) may not have any symptoms. The type of thalassemia that a person has depends on how many or which type of thalassemia a person has inherited from their parents. For example, if a person receives a beta thalassemia trait from his father and another from his mother, he will be considered beta thalassemia major. If a person receives an alpha thalassemia trait from her mother and the normal alpha genes from father, she would be referred to as having alpha thalassemia minor. These patients are asymptomatic but may act as carriers of these genes to their respective children. Health complications are mostly observed in thalassemia major and intermediate patients.
Accurate and timely diagnosis plays an important role in the overall patient management. Routine blood tests, Hemoglobin analysis, and family molecular studies can demonstrate whether a person is suffering from thalassemia, or he or she is a carrier. As a matter of fact, the concept of expanded carrier screening using high-end genomics testing using next generation sequencing for thalassemia, hemoglobinopathies and other genetic disorders are already gaining tremendous attention in recent times.
Screening of individuals at increased risk of being carriers for thalassemia can identify couples with a 25 per cent risk of having a baby with a significant genetic disorder for which prenatal diagnosis is likely. If both parents are carriers, they may consult with a well-trained genetic counsellor who can help in determining whether to conceive or have a fetus evaluated for thalassemia. This approach can prove to be very effective in preventing and declining the incidence of thalassemia major.
Prenatal testing can be done around the 11th week of gestational age by carrying out genomic-based mutation analysis (alpha and beta gene) on DNA extracted from chorionic villi or amniotic fluid after 16th to 18th week of pregnancy. Furthermore, invitro fertilisation is also a good option for carriers who don’t want to risk giving birth to thalassemia major child. Newer techniques like pre-implantation genetic diagnosis, used in combination with in vitro fertilisation, may help parents who have thalassemia or carry the trait to give birth to a healthy normal children without the disease. The invitro fertilized embryos can be subjected to DNA mutation analysis at the 5th cell stage for the thalassemia gene before being implantation, selecting only the normal embryos.
Management and treatment of thalassemia patients depend on the extent of severity. Treatment for those with more severe disease often includes regular blood transfusions, iron chelation, and folic acid. Thalassemia patients who do not respond well to blood transfusions can be prescribed to take hydroxyurea.
Most recently, a breakthrough development in the management of thalassemia patient has been reported by an international phase-3 clinical trial from Rome and phase The group of researchers used “Gene therapy” (a technique that modifies a person’s genes to treat or cure disease) to treat the severely affected beta thalassemia patient. During this process, the fully functional good beta chain genes were added to the patient’s body after clearing the abnormal hematopoietic stem cells carrying the defective genes.
The trial patients have been followed up for years now, and their normal hemoglobin production is stable indicating that gene therapy offers a viable cure for beta thalassemia. Another alternative approach which is currently being explored to fix the defective gene is use of CRISPR (a techniques which helps in editing the gene). Although these recent techniques look promising, its high cost and necessary infrastructure requirement may limit its availability at the global level. Nevertheless, these developments certainly show rays of hope for Thalassemia. There’re some exciting times ahead and we just need to keep going.
The author is Section Head, Molecular Pathology, Department of Molecular Genomics, SRL Diagnostics. Views are personal.
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