موتاسیون‌های نادر و کم‌شیوع بتاتالاسمی در استان قزوین-ایران

   Background and Aim: About 13 beta-globin mutations encompass 70-90% of the mutation spectrum in Iran. These mutations are called common beta-globin mutations. The rest are rare or unknown mutations. The objective of this study was to identify the rare or unknown beta-globin mutations in Qazvin province.   Materials and Methods: In this descriptive-analytic study, EDTA-containing venous blood samples were collected from 100 patients with transfusion-dependent beta-thalassemia referring to Qods hospital of Qazvin. Age, sex, ethnicity, history and consanguinity between parents were recorded by reviewing the patients files. Screening for causal mutations was carried out on DNA isolated from WBCs of the patients by using ARMS technique. To explore the other mutations in the beta globin gene, direct sequencing analysis was applied for DNA samples when no mutation was detected with ARMS. For data analysis SPSS V. 13.5 was used.   Results: Based on the results, 85.9% of alleles were identified by ARMS technique, while direct sequencing uncovered the remaining alleles (14.1%). Total 20 different mutations discovered by this two-step approach (11 mutations with ARMS and 9 mutations with sequencing). Abundant alleles   (IVS-II-1, IVS-I-110, FSC8/9) accounted for 59.3 % of the mutations. IVS-II-1 with a frequency of   31.3% was the most common, while nt-30, IVS-I-6, Cd5, IVS-II-745, 5´ UTR, Cd15, Cd39, IVS-I-130, Cd24, Cd74/75, HbS and Hb Monroe mutations were observed with the least frequency (each about 1% or less).   Conclusion: Molecular analysis of beta thalassemia has shown that in addition to the common mutations, many rare beta-globin mutations responsible for the disease are present in the Qazvin population.We have revealed the existence of 8 rare mutations from Qazvin, two of which (Cd74/75 and Hb Monroe) are the first reported in Iran.