Beta-thalassaemia in Campania: DNA polymorphism analysis in beta A and beta thal chromosomes and its usefulness in prenatal diagnosis.

In order to evaluate the feasibility of first trimester prenatal diagnosis of beta-thalassaemia by restriction fragment length polymorphism (RFLP) in Campania, one of the most affected regions in Southern Italy, DNA polymorphism analysis was performed on 40 unrelated patients, affected with homozygous beta-thalassaemia, and on their parents. Frequency of the presence of the Hinc II epsilon, Hind III G gamma and A gamma, Hinc II psi beta and 3' psi beta, Ava II psi beta, Ava II beta and Bam HI 3' beta sites have been determined in the beta A and beta thal chromosome samples. In 31 families (over 75%), RFLPs enabled tracing the beta-thalassaemia mutations in both father and mother (100% diagnosis). In the remaining nine families, RFLPs enabled tracing only one of the two mutations (50% diagnosis) because the other parent was found to be homozygous in all the analysed polymorphic sites. Restriction haplotypes, assembled on the basis of linkage analysis, were most heterogeneous, hence a wide heterogeneity of mutations is expected.