PRENATAL-DIAGNOSIS FOR THALASSEMIA IN A MULTICULTURAL SOCIETY

The provision of a prenatal diagnosis service for thalassaemia is beco ming more demanding. In an ethnically-diverse community, the number of mutations has increased. Requests for prenatal testing continue to co me at an advanced stage in pregnancy, often without the underlying mut ation having been identified. Although controls are included in PCR as says, errors can still occur. The alternative to DNA testing, i.e., an alpha/beta globin chain synthesis ratio on a fetal blood sample, is n ow less readily available. In the circumstances described, the laborat ory must adopt a more efficient and reliable approach to DNA mutation analysis. With currently available technology, this improvement is mor e likely to come through increased automation. To achieve this aim, we have moved to capillary electrophoresis. With capillary electrophores is we are able to use a PCR-based screening strategy which can detect up to 11 beta thalassaemia mutations. The actual prenatal test is unde rtaken using two independent PCRs thereby reducing the potential for e rror. Despite the advantages of PCR, similar to 12 per cent of beta th alassaemia and about nine per cent of alpha thalassaemia cases require further study in our experience. In this situation, capillary electro phoresis has again proven helpful since a DNA scanning approach, such as single strand conformation polymorphism, can be automated to identi fy the region of DNA to be sequenced. (C) 1998 John Wiley & Sons, Ltd.