Edema due to Thalassemia and how to prevent it

This is an automatically translated article.

Posted by Dr. Ly Thi Thanh Ha - Medical Genetics Block, Vinmec High Technology Center

Thalassemia is an autosomal recessive genetic disease. Thalassemia is divided into two main types: alpha and beta thalassemia, depending on the mutation in which gene causes deficiency in alpha or beta hemoglobin chain synthesis.

1. What is edema for Thalassemia?

Thalassemia is an autosomal recessive genetic disease. Thalassemia is divided into two main types: alpha and beta thalassemia, depending on which mutation causes a deficiency in alpha or beta hemoglobin chain synthesis.
In normal people, there are 4 alpha globin genes that are functional. Mutations in the alpha globin gene can cause loss of 1, 2, 3, or a complete loss of 4 alpha globin genes.
Hb Bart's edema syndrome is the most severe form of α-thalassemia, due to the complete loss of 4 α globin genes, resulting in a complete decline in the ability to produce α globin chains. Children with HbBart's have Hb components in their red blood cells that are mainly non-functional Hb γ4 and β4. However, there is still some amount of Portland fetal Hb (δ2γ2) remaining, which is the only type of Hb that has the function of transporting oxygen to maintain the fetus's life. Pregnant women with Hb Bart's have edema, heart failure, and anemia that persist from the intrauterine stage. In addition, hepatosplenomegaly, brain retardation, skeletal system and cardiovascular system develop abnormally, thick placenta. Babies with Hb Bart's most often die during pregnancy (23-38 weeks) or soon after birth. There are only a few reported cases of survival thanks to intensive treatment and blood transfusion in the neonatal period.

2. How to prevent the cause of thalassemia due to edema?

The fact that 4 alpha globin genes are damaged in the fetus causing fetal edema is due to simultaneous inheritance from both parents. Both parents are carriers of the loss of 2 alpha globin genes, the risk of passing it on to the baby is 25%.
To avoid this, there are 2 possible ways:

2.1 Prenatal diagnosis for the fetus

The time to perform prenatal diagnosis if performed with amniotic fluid samples is at 16-18 weeks of gestation, with chorionic villus sampling, it can be performed at 10-12 weeks earlier. Each specimen type has its own advantages and disadvantages. The genetic counselor will explain the issues related to the test meaning, limitations of each type of test for the client to understand and decide on the choice.

2.2 Pre-implantation genetic diseases (PGD)

PGD is a pre-implantation genetic diagnosis method to help infertile couples screen, remove malformed embryos and have healthy babies. The method is performed by biopsy of 1 cell from embryos obtained through IVF when the embryo is 5 days old. These cells will then be tested for early detection of potential genetic abnormalities from both parents to remove faulty embryos to ensure that the child is born without genetic diseases. .

Vinmec International General Hospital has implemented a pre-pregnancy health care and counseling program with services including a screening program to detect healthy people carrying disease genes. As one of the leading units in the field of examination, counseling and intervention to support fertility, Thalassemia screening for couples preparing to enter marriage, or married couples who do not know yet. Do I carry the disease gene?
Although congenital hemolysis is a disease that is diagnosed and treated not too complicated, but this is a disease inherited from generation to generation, the cost of treatment is very expensive, so to give birth healthy baby in modern life, genetic screening before marriage is extremely important.

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