SCREENING OF HEMOGLOBINOPATHIES AND MOLEC ULAR ANALYSIS OF BETA-THALASSEMIAS IN CENTRAL TUNISIA

Background. - Previous investigations have permitted to locate 16 beta -thalassemic mutations in different samples of the Tunisian population . One of them (IVS I nt 2: T--G) had been found only in the central re gion of Tunisia. Our research was carried out in this part of the coun try to estimate the prevalence of this mutation and to establish a pre natal diagnosis using appropriate probes. Population and methods. - On e thousand one hundred and five blood samples taken from 1987 to 1990 from healthy blood donors and 346 samples taken from 1985 to 1992 from patients were analysed. Detection of hemoglobinopathies was carried o ut by means of specific hematological tests and different electrophore tic and chromatographic techniques. Mutations were detected by means o f the usual techniques of molecular biology. Results. - Sickle cell an emia and beta-thalassemia were the most frequent in the samples studie d. The molecular analysis carried out on eight patients native of the Essouassi-El-Djem region point out that all these patients carry the s ame point mutation (IVS I nt 2: T-G) detected for the first time in 19 88 in a patient native of the same region. One of these patients, aged 43, who did not suffer from anemia and did not show the usual symptom s of beta0 thalassemia, had one hemolytic attack at the age of 17. Con clusions. - The high number or persons carrying Hb S and beta-thalasse mia trait increase the risk of appearance of homozygous forms. The pre sence of the same mutation IVS I nt 2: (T-G) in all beta0-thalassemic patients from Essouasi-El Djem region may indicate that it may have it s origin there. The heterogeneity of clinical phenotype of these patie nts shows the difficulty of establishing a unique strategy of prenatal diagnosis by DNA analysing which can be applied in all cases.