Prenatal diagnosis of beta-thalassemia in Southern China

To control the birth of thalassemic children in Southern China.

DNA-based diagnosis was offered on fetal tissues in pregnancies when beta-globin gene mutations were identifiable in both parents using polymerase chain reaction (PCR)-reverse dot blot (RDB) assay. An automated high-performance liquid chromatography (HPLC) system was used to analyze fetal hemoglobin in pregnancies when mutation was unidentified in at least one parent. Fetal samplings were collected by chorionic villi sampling (CVS) in the first trimester, and by amniocentesis or cordocentesis in the second trimester. Maternal contamination of fetal DNA was ruled out by short tandem repeats (STR) analysis.

Five hundered and forty-five fetuses of 540 at-risk pregnancies were performed prenatal diagnosis. Out of 540 fetuses tested by DNA analysis, 150 were found to be normal, 257 were carriers, whereas 133 were affected. Out of five fetuses diagnosed by HPLC, one fetus was affected and four were unaffected. Totally, 133 pregnancies with affected fetuses, except for one twin pregnancy, were voluntarily terminated, leading to a marked reduction of severe beta-thalassemia in this region.

Our prenatal diagnosis strategy proved to be highly effective. DNA- and HPLC-based testing could enable prenatal diagnosis of beta-thalassemia in all at-risk pregnancies.