Invasive prenatal diagnosis of α-thalassemia to control Hb Bart's hydrops fetalis syndrome: 15 years of experience.

OBJECTIVE

The aim of the present study was to report experiences with invasive prenatal diagnosis of α-thalassemia for the prevention of Hb Bart's hydrops fetalis syndrome in the Guangxi Zhuang Autonomous Region, China.

METHODS

Pregnant women and their partners who tested positive for α0-thalassemia or were diagnosed with HbH diseases were counseled and suggested to undergo a prenatal diagnostic procedure for α-thalassemia. Fetal material was obtained by chorionic villus sampling (CVS) between 9 and 13 weeks of gestation, by amniocentesis between 16 and 24 weeks of gestation and by cordocentesis after 24 weeks of gestation. The α0-thalassemia gene types were detected by gap polymerase chain reaction (Gap-PCR). All results were finally confirmed by DNA analysis after delivery or termination of pregnancy.

RESULTS

An invasive prenatal α-thalassemia diagnosis was performed in 3155 cases at risk for Hb Bart's hydrops fetalis syndrome at our hospital from 2002 to 2016. CVS was performed in 1559 cases (49.4%), amniocentesis in 1240 cases (39.3%) and cordocentesis in 356 cases (11.3%). In total, 786 fetuses were diagnosed as Hb Bart's hydrops fetalis syndrome. Among these cases, the α-thalassemia genotype was --SEA/--SEA in 784 cases and --SEA/--THAI in 2 cases. All affected pregnancies were terminated in time.

CONCLUSIONS

This extensive experience suggests that carrier screening, molecular diagnostics, genetic counselling, and prenatal diagnosis are effective measures to prevent Hb Bart's hydrops fetalis syndrome.