HbA2-Yokoshima (delta 25(B7)Gly >Asp) and Hb A2-Yialousa (delta 27(B9)Ala>Ser) in Turkey

Heterozygous beta-thalassemia (β-thal) carriers are characterized by microcytosis, hypochromia, and elevated HbA2 levels (≥3.5%) [1]. Although an elevated HbA2 level is a diagnostic parameter for β-thal, the interaction between d-globin gene mutation and β-thal can result in a normal HbA2 level, leading to misdiagnosis [2]. As δ-thalassemia (δ-thal) has no clinical significance, a reduced HbA2 level in β-thal carriers is an important parameter in the presence of δ-thalassemia [3]. δ-globin gene mutations (http:// globin.cse.psu.edu/hbvar/menu.html) have been reported [4]. HbA2-Yialousa (delta 27(B9)Ala>Ser) is the most common δ-thal mutation in the Mediterranean Region and was first identified by Trifillis et al. in a Sardinian family in 1991 [1,5]. HbA2-Yokoshima (delta 25(B7)Gly >Asp) was first identified in a Japanese family in which 1 member was homozygous [6].