Effectiveness of β-thalassemia prenatal diagnosis in Southern Iran: a cohort study.

Abstract

The aim of this study was to evaluate the effectiveness of prenatal diagnosis (PND) for the prevention of thalassemia in Southern Iran. From 2004 to 2012 1346 couples with β-thalassemia minor were referred to our center. Mutation analyses utilized different methods including polymerase chain reaction-based technique of amplification refractory mutation system (ARMS), Restriction Fragment Length Polymorphism Analysis of PCR-Amplified Fragments (PCR-RFLP) and Gel Electrophoresis and direct sequencing. Haplotype analysis of the β-globin gene cluster was done routinely using the PCR-RFLP technique. Of the 1346 couples, 884 (66%) requested PND. They had a total of 985 pregnancies (954 singleton and 31 twin pregnancies): the 1016 fetuses underwent chorionic villus sampling (CVS). Thalassemia major was diagnosed in 266 cases (26.2%), and termination of pregnancy was requested by the parents in 264 of them (99%). Thalassemia trait was detected in 499 (49.1%) and 251 cases (24.7%) showed no β-thalassemia mutations. There were three misdiagnoses (0.4%) (affected children diagnosed as carriers at PND). A unique pattern of thalassemia mutations was present in the study population, with IVS II-I (G→A), C36-37(-T), IVS I-5(G>C), -25bpdel (252-276), IVS I-110(G>A) and C44 (-C) being present in 62% of cases. The pattern of distribution of thalassemia mutations differs among ethnic groups within the same country.