Evaluation of Alpha-Thalassemia Mutations in Cases with Hypochromic Microcytic Anemia: The İstanbul Perspective.

Abstract

Abstract:Objective: Alpha thalassemia syndromes are caused by mutations on one or more of the four α-globin genes. Mutations couldbe either more commonly deletional or non-deletional. As some deletions (3.7 and 4.2) cause α+-thalassemia, some cause(-20.5, MED, THAI, FIL) α0 -thalassemia. The aim of this study was to determine alpha thalassemia mutations in patients withunsolved hypochromic microcytic anemia and to evaluate types of mutations.Material and Methods: Two hundred six patients with hypochromic microcytic anemia were evaluated for alphathalassemia. A venous blood sample of 2 mL was drawn from each patient for DNA isolation. The samples were investigatedfor α-thalassemia mutations by using the Vienna Lab α-Globlin StripAssay TM commercial kit.Results: Fourteen different mutations were determined in 95 (46.1%) patients. The most common mutation was the 3.7single gene deletion and was found in 37 patients (n=37/95, 39%). Others common mutations were the 20.5 kb double genedeletion (n=20 patients, 21%), MED double gene deletion (n=17 patients, 17.9%), α2 IVS1 (n=10 patients, 10.5%), α2 cd142Hb Koya Dora (n=6 patients, 6.3%), α2 polyA1 (Saudi type) (n=6 patients, 6.3%), 4.2 single gene deletion (n=4 patients, 4.2%),α1 cd14 (n=2 patients, 2.1%), and -FIL mutation (n=2 patients 2.1%), respectively. Hb Adana, Hb Icaria, α2 init cd and α2polyA2 (Turkish type) were found in 1% of the patients (n=1). Seven patients (7.4%) had α-thalassemia triplication. In ourstudy, three mutations (Hb Icaria, α1 cd14, α2 init.cd) were determined firstly in Turkey. Seven mutations (-SEA, -THAI, HbConstant Spring, α2 cd19, α2 cd59, α2 cd125, Hb Paksé) were not determined in this study.Conclusion: Alpha thalassemia should be considered in the differential diagnosis of hypochromic microcytic anemiaespecially in cases without iron deficiency and b-thalassemia carrier state. Genetic testing should be performed for thesuspicious cases. We also recommend that a national database with all mutations in Turkey should be created to screen thealpha thalassemia cost-effectively.