Published: May 8, 2020 2:21:51 pm
By Dr Uma Vaidyanathan
Thalassaemia is a disorder of the haemoglobin structure. A tetramer molecule present in the RBCs, haemoglobin is responsible for supplying oxygen in the body and is a rich source of protein in the blood. The human Hb/HbA has two sets of globin chains. These are a-globin chain and ß-globin chain. Four genes (two inherited from the mother and two from the father) regulate the production of a-globin chain, while only two genes (each inherited from father and mother) control the production of ß-globin chain.
The thalassaemia syndromes are characterised by a basic defect in the synthesis of one type of globin chains. As a result, there is insufficient Hb content in the resultant red cells, leading to decreased haemoglobin concentration, anaemia and need for multiple blood transfusions in severe cases.
Each year, more than 70,000 babies are born with thalassaemia worldwide and this defect is very often seen in the Indian subcontinent. Haemoglobin electrophoresis is the gold standard in diagnosing this condition. Patients with thalassemia traits do not require long-term monitoring. They usually do not have iron deficiency, so iron supplements are unlikely to improve their anemia.
In alpha thalassaemia, the hemoglobin does not produce enough alpha protein. To make alpha-globin protein chains we need four genes, two on each chromosome 16. We get two from each parent. If one or more of these genes is missing, it will result in alpha thalassemia. The severity of thalassemia depends on how many genes are faulty, or mutated.
One faulty gene: The patient has no symptoms. A healthy person who has a child with symptoms of thalassemia is a carrier. This type is known as alpha thalassemia minima.
Two faulty genes: The patient has mild anemia. It is known as alpha thalassemia minor.
Three faulty genes: The patient has hemoglobin H disease. This is a type of chronic anemia. In this case, the patient needs regular blood transfusions throughout their life.
Four faulty genes: Alpha thalassaemia major is the most severe form of alpha thalassemia. It is known to cause hydrops fetalis, a serious condition in which fluid accumulates in parts of the fetus’ body. A fetus with four mutated genes cannot produce normal hemoglobin and is unlikely to survive, even with blood transfusions.
Two globin genes are required to make beta-globin chains: one gene from each parent. Beta thalassaemia is caused when one or both genes are faulty.
Severity depends on how many genes are mutated.
One faulty gene: This is called beta thalassaemia minor.
Two faulty genes: There may be moderate or severe symptoms. This is known as thalassaemia major (earlier known as Colley’s anemia).
Medical management of thalassaemia major depending on severity would be:
• Blood transfusions
• Chelation therapy – removal of excess iron overload in body
• Bone marrow transplant
• Gene therapy
Management during Pregnancy can be divided as follows:
Screening and counseling pre-pregnancy: Screening can identify couples having 25 per cent risk or more of having a pregnancy with signi?cant haemoglobinopathy. If a pregnant woman is found to be a carrier of haemoglobinopathy, the partner needs to be screened as soon as possible. If a risk of the fetus having major haemoglobinopathy is detected, urgent expert counselling is provided to the couple so that they can make an informed choice regarding the prenatal diagnosis and the possible termination of pregnancy.
Folic acid supplementation: Beginning in the preconceptual period, at least three months prior to conception, folic acid in the dosage of 5 mg/day helps in preventing neural tube defects.
Some additional tests also might be needed. Doctor might ask the patient to take blood sugar and thyroid function tests. Patients could be asked for cardiovascular assessment. Ultrasound of liver and the gallbladder (and spleen, if present) should be performed. This helps in detecting gallstones and evidence of liver cirrhosis due to iron overload or transfusion-related viral hepatitis.
Women with thalassaemia should be reviewed on a monthly basis until 28 weeks of gestation and fortnightly thereafter. Women with thalassaemia are best treated in a multidisciplinary team setting, including an obstetrician with expertise in managing high-risk pregnancies and a hematologist.
An early scan after 7 to 9 weeks of gestation is needed to determine viability as well as the presence of a multiple pregnancy. A detailed anomaly scan must also be done after 11-12 weeks and 18 to 20 weeks of gestation. Later, ultrasounds may be needed to assess foetal growth restriction.
Care during labour and delivery
Thalassaemia is not an indication for cesarean section. Patients may need blood transfusion in case of excessive blood loss during the delivery.
Women with thalassemia are at high risk for venous thromboembolism due to the presence of abnormal red blood cells in the circulation.
Breastfeeding is safe and should be encouraged. In addition, there is no contraindication to the use of hormonal methods of contraception, such as the combined oral contraceptive pill, the progestogen-only pill, hormonal implants, and the Mirena intrauterine system in women with thalassaemia.
(The writer is Senior Consultant, Obstetrics and Gynecology Fortis Hospital, Shalimar Bagh.)
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