BETA THALASSEMIA & ITS PRENATAL DIAGNOSIS
What is Thalassemia?
Thalassemia is the most common inherited(genetic) blood disorder, in which patients is unable to generate sufficient red blood cells and needs regular blood transfusions (every 2-3 weeks) to survive.
What causes beta thalassemia?
It is caused by a change in the gene that makes haemoglobin.
- If two genes (one from each parent) are affected – it results in Thalassemia major/ intermedia.
- If only 1 of these genes (from one parent) is affected- it results in a carrier condition.
What are the manifestations of different type of beta-thalassemia?
- Beta thalassemia major– present with severe anaemia, need regular blood transfusions
- Beta thalassemia intermediate: – variable severity, may need a blood transfusion
- Beta Thalassemia minor/ trait – asymptomatic/ mild anaemia carries the abnormal gene and transmits it to the next generation.
What is the prevalence of beta-thalassemia in India?
India is considered thalassemia capital with the largest number (10%) of children with Thalassemia major. The average prevalence of beta-thalassemia carriers is 3% to 4% in India.
How can we prevent beta thalassemia?
Prevention of new disease is possible with proper education, carrier screening and timely prenatal diagnosis. Screening for the identification of carriers forms an integral component of a prevention program.
Whom to screen for Thalassemia?
It is important to screen all expectant mothers premarital, preconception, or early pregnancy through a blood test. A partner screening is recommended if a positive test result of his spouse Blood samples of family members of thalassemia patient is also recommended.
How to confirm thalassemia status?
A molecular genetic test (DNA analysis) is used to confirm mutations in beta globin-producing genes.
If I have beta-thalassemia, what should I do before becoming pregnant?
If you have beta thalassemia, preconception counselling with a maternal-fetal medicine specialist is recommended to optimize your health & to discuss the option of prenatal screening & diagnosis.
Can I pass the beta-thalassemia gene on to my baby?
Baby will inherit one gene from you and one from your partner. If you have beta-thalassemia major or intermedia, you will pass the affected gene on to your baby. Whether your baby will have beta-thalassemia major depends on whether your partner also has Thalassemia.
- If your partner does not carry any thalassemia, your baby will be a healthy carrier of beta-thalassemia.
- If your partner has a beta-thalassemia major or intermedia or is a carrier, there is a chance that your baby will have a beta-thalassemia major.
Will all of my babies be affected with Thalassemia if both partners are beta-thalassemia carrier?
Thalassemia is an autosomal recessive blood disorder. There is only a 25% (1in 4 babies) chance of having thalassemia major if both partners are thalassemia carrier, 50% will be thalassemia carrier, Or 25% will be normal.
Is the diagnosis of Thalassemia of the unborn fetus is possible?
Prenatal diagnosis of Thalassemia can be done by chorionic villus sampling (CVS) or amniocentesis if both partners are thalassemia carrier. Facility for IVF with PGD (Pre Implantation genetic diagnosis) is also available in a condition where both partners are affected.
What are the risks to me and my baby in pregnancy if I have beta-thalassemia major, and what extra care will I receive?
Risk for anaemia, gestational diabetes, hypothyroidism, cardiac decompensation, risk of developing blood clots in their legs (deep vein thrombosis or DVT) is increased compared with women who are not pregnant. You will need multidisciplinary care with regular blood transfusions, iron chelation therapy, regular monitory of your blood sugar, thyroid function, liver & cardiac status.
Thalassemia can also affect fetal growth & you will require close fetal growth monitoring by ultrasound scans.
Whom to consult if I have concern for Thalassemia?
Maternal-fetal medicine Specialist & Genetics will provide you counselling & will help you to decide partner selection, reproductive options, birth control and prenatal diagnosis.
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