Prenatal control of Hb Bart's disease in southern China.

Alpha-thalassemia (thal) is one of the most common genetic diseases and is widely distributed in southern China. Fetuses with homozygous alpha(0)-thal, known as Hb Bart's (gamma(4)) disease, usually die during the last trimester of gestation, and the affected pregnancies are frequently associated with serious maternal morbidity and mortality. Prenatal diagnosis is needed for early detection of this disease in couples at-risk. This can be performed by invasive fetal sampling or by serial ultrasonography to detect affected fetuses followed by invasive testing. Of 122 at-risk families who received prenatal testing, 98 (80.3%) chose ultrasonography, and 24 (19.7%) chose direct invasive testing. In all, 28 affected pregnancies were detected and terminated. Ultrasonography is now playing a major role in prenatal control of Hb Bart's disease in our region, and limits the invasive procedures to the few patients identified to be at high risk.