ABSTRACT
Thalassemias are the most common hereditary disease in Iran, resulting from defects in synthesis of one or more hemoglobin [Hb] subunits. The majority of patients suffer from beta-thalassemia [thal], but cases with microcytic hypochromic anemia and normal electrophoretic patterns are suspected to have alpha or silent beta-thalassemia. A family from the northern part of Iran, an area where thalassemias, are highly prevalent was referred to us for prenatal diagnosis. The hematological data of the father indicated a pattern of beta-thal minor. Reverse hybridization analysis for the most common beta-globin mutations identified IVS-II-1 [G-A] in the heterozygous state. The maternal laboratory data indicated a case more compatible with alpha-thal. Iron deficient anemia was ruled out, and common alpha-thal point mutations and deletions were investigated. As no mutation was detected, globin chain synthesis was performed and showed an alpha/beta chain ratio of 2.1, that was in the range of beta-thal minor. DNA sequencing of the entire beta-globin gene identified a heterozygous GTG-GGG [Val-Gly] mutation at codon 126, also known as Hb Dhonburi [Neapolis]. Prenatal diagnosis of the fetal DNA showed the absence of the IVS-II-1 and codon 126 anomalies. This result demonstrates the importance of screening of individuals with mild microcytic hypochromic anemia for both alpha- and silent beta-thal mutations