Prenatal diagnosis of alpha-thalassaemia by analysis of enzymatically amplified DNA sequences.

A new method using enzymatically amplified DNA sequences for the prenatal diagnosis of alpha-thalassaemia was evaluated. DNA from a foetus at risk for alpha(0)-thalassaemia was analysed to detect the presence of alpha-globin genes. The procedure involved amplification of a 136-base-pair (bp) region of the alpha-globin gene complex between the psi alpha and alpha 2 region. Amplification was performed using a pair of oligonucleotide primers and a heat stable DNA polymerase which allowed repeated cycles of DNA synthesis at 72 degrees C. A 136 bp product was detected by gel electrophoresis indicating the foetus was not positive for Bart's hydrops foetalis. The result was confirmed using the gene mapping technique. Prenatal diagnosis of alpha-thalassaemia by DNA amplification offers two advantages over the gene mapping technique since radionucleotides are not used and results can be obtained in 3 days.