Prenatal diagnosis of beta-thalassaemia by coelocentesis

Coelomic fluid and placental tissue were obtained from four women undergoing termination of pregnancy at 7-9 weeks gestation for psychological reasons. All four women and their partners were known carriers of beta-thalassaemia and DNA analysis in their blood identified the mutation carried by each of them. Allele-specific polymerase chain reaction and denaturing gradient gel electrophoresis techniques were used to detect and identify the mutations in the DNA extracted from the coelomic cells and placental tissue. Three fetuses were found to be carriers of either the paternal or maternal mutation, while one was found to be affected by beta-thalassaemia. There was concordance in the results obtained from the chorionic villi and coelomic cells. Amplification of the apolipoprotein B gene variable number tandem repeats (VNTR), in the DNA of the coelomic cells showed normal segregation of alleles in the fetuses, thus excluding maternal contamination. The results of this study demonstrate that coelocentesis may be a reliable alternative technique for the diagnosis of beta-thalassaemia from as early as 7 weeks gestation.