A simple sensitive prenatal test for hydrops fetalis caused by alpha-thalassaemia.

Slot blot analysis was used to differentiate between the genotypes of homozygous alpha-thalassaemia and those of haemoglobin-H disease and alpha-thalassaemia trait. The method is simple and rapid because restriction enzyme digestion and gel electrophoresis are not needed. Because of the great sensitivity of the test, as little as 0.5 micrograms of DNA can be studied with an 35S-labelled probe which has a longer isotopic half life than the 32P probes normally used for gene mapping. This assay should facilitate prenatal diagnosis in countries where pregnancies at risk for alpha-thalassaemia are common.