Thalassemia Carrier Screening

Thalassemia, also known as Mediterranean anemia, is an autosomal recessive genetic disorder. Thalassemia usually results from a gene deletion or a point mutation. Infants inherited the abnormal genes

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Thalassemia is one of the most common inherited disorders in Taiwan, which include α‐thalassemia and β‐thalassemia. Approximately 6% of the population are carriers of this disorder, of which 4% are carriers of α-Thalassemia, and 2% are carriers of β-Thalassemia. In general, there was no significant difference between carriers and screen-negative individuals.

If both parents are carriers of α-Thalassemia or β-Thalassemia, for each pregnancy, there is a 25% chance that the child will be normal, a 50% chance that the child will be a thalassemia silent carrier, and a 25% chance that the child would have severe thalassemia.

If a fetus suffers from β-thalassemia, it can be difficult to detect abnormalities via ultrasound. However, the infant will begin to show signs of anemia a few months after birth.


• Family history of Thalassemia

•Individuals with Thalassemia gene mutations are referred to as carriers

•Pre-marital health examination or prenatal genetic test

•First Trimester of pregnancy


For a fetus inherited thalassemia, both parents must carry the abnormal gene for the same type of thalassemia. Although carriers generally have no symptoms or only display minor anemia, we can identify carriers during the first prenatal exam based on mean corpuscular volume (MCV).

If an expecting mother has an abnormally low MCV, (i.e. tests lower than 80 fL), then the father will be asked to take the MCV test as well. If the father also tests lower than 80 fL, then both parents will request ferritin tests, hemoglobin electrophoresis tests, and genetic tests to confirm whether they are carriers of the same type of thalassemia (α or β).

Fetuses with parents who are carriers of the same type of thalassemia will require a prenatal genetic diagnosis for thalassemia via villus sampling, amniocentesis, or fetal blood sample. Expecting parents are also strongly advised to undergo further genetic counseling to prevent the birth of children with severe thalassemia.

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