Prevention of Hb Bart's (γ4) Disease Associated with the - -(THAI) α(0)-Thalassemia Deletion in Mainland China.

α-Thalassemia (α-thal) is a common inherited disease in southern China. The severest form is Hb Bart's (γ4) disease, in which the affected fetuses almost always die in utero or shortly after birth, and the mothers are at high risk for severe morbidity. The most common type of α(0)-thalassemia (α(0)-thal) in southern China is Southeast Asian (- -(SEA)) deletion. Occasionally, Hb Bart's disease, caused by a compound heterozygosity for the - -(SEA) and - -(THAI) α(0)-thal deletions, can also be encountered. In this study, we report our experience with the prevention of Hb Bart's disease associated with the - -(THAI) α(0)-thal deletion. A total of 385 couples at risk for Hb Bart's disease, including seven who tested positive for the - -(SEA) deletion in one partner and the - -(THAI) deletion in the other, were found. Different prenatal procedures were offered, depending on the gestational age at presentation. Sixty-six affected fetuses were diagnosed prenatally; among these, two cases of Hb Bart's disease were compound heterozygotes for the - -(SEA) and - -(THAI) deletions. All affected pregnancies were terminated in time. We also presented a diagnostic protocol for identification of α(0)-thal trait that can reduce the number of samples for detection of the - -(THAI) deletion.