Prenatal diagnosis of Chinese homozygous a-thalassaemia 1 and haemoglobin H disease by analysis of a- and phi zeta -globin genes in chorionic villi and amniocytes

Eighty-eight high-risk pregnancies, 81 for homozygous a-thalassaemia 1 and 7 haemoglobin (Hb) H disease, were collected in this study. Chorionic villus sampling (CVS) was done in 63 cases and amniocentesis in 25 cases to obtain fetal cells. Southern blotting and DNA hybridization with a- and phi zeta -globin gene probes were used to determine the a-globin gene status. In two non-informative families with non-deletional mutations, DNA analysis failed to rule out the affected condition, and fetal blood sampling (FBS) and Hb electrophoresis were used for the final diagnosis.