Establishment of prenatal diagnosis for beta-thalassaemia: a step towards its control in a developing country.

Beta-thalassaemia constitutes a major health burden on the limited health resources of India and prenatal diagnosis is seen as an important preventive measure to reduce the burden of the disease. Prenatal diagnosis has been offered to 99 women in 112 pregnancies by fetal DNA analysis, using a PCR-based Amplification Refractory Mutation System (ARMS) for the common and uncommon Indian mutations. Restriction fragment length polymorphism (RFLP) for the beta-globin gene was used when the mutation remained unidentified in one of the parents or to complement the ARMS result. In 53 cases the fetus tested had beta-thalassaemia trait (betaTT) (47.3%), 22 were normal (19.6%) and 31 had thalassaemia major (27.6%). In five cases (4.5%), a definitive report could not be given due to maternal contamination. In one case (0.9%), there was a misdiagnosis. Pitfalls encountered in the diagnosis were maternal contamination and occasional non-amplification of the primers. Having established a regional centre for the prenatal diagnosis for thalassaemia, the screening programmes will be enlarged both to identify carriers and prevent the birth of further homozygous children, even during the first pregnancy.