Background: Thalassaemia is the most common hereditary disease in Southeast Asia. In Vietnam, the carrier rate for β-thalassemia varies from 1.5% to 25% depending on the ethnic groups of the population.
Objective: To evaluate the effectiveness of the first screening program for control of α- and β-thalassemia in a group of high-risk pregnancy patients who attended our clinic from January 2012 to April 2015.
Methods: The identification of pregnancies at risk was done retrospectively and prospectively. A total of 944 women with reduced levels of mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) were referred to the Human Genetics Department where, together with their husbands, were screened using standard protocols. If both members of the couple were positive for these markers, then determination of the thalassemia carrier status by DNA analysis was considered and the pregnancy was considered at risk.
Results: Out of the 944 couples tested, 754 pregnant women and 385 husbands were positive. Among the 754 women, 493 (65.3%) were α-thal carriers; 204 (27.1%) β-thal carriers; 40 (5.3%) α- and β-thal carriers and 17 (2.2%) were positive for hemoglobin H disease (HbH). Among the men, 300 (77.9%) were α-thal carriers, 37 (9.6%) β-thal carriers; 37 (9.6%) α- and β-thal carriers and 11 (2.9%) were positive for HbH disease. In total, we identified 508 couples at risk, 306 prospectively (284/306 homozygous α0-thal, 19/306 β-thal, 3/306 both α0-β-thal) and 202 retrospectively (166/202 β-thal, 36/202 HbH disease). After genetic counseling, prenatal diagnosis by fetal DNA analysis was performed on 312/508 (61.5%) couples including 91 pregnancies at risk for homozygous α0-thal, 36 at risk for HbH disease, and 185 at risk for β-thal major.
