A Novel Mutation of the δ-Globin Gene in an Asymptomatic 30-Year-Old Female

hinder the diagnosis of the β-thalassemia trait [4]. Values of HbA2 >3.2% associated with microcytosis characterize the β-thalassemia trait [3]. However, the coinheritance of β-globin and δ-globin gene mutations can decrease HbA2 values to normal or lower levels due to a decreased δ-chain production. As iron deficiency anemia is also characterized by low HbA2 levels, this disease must firstly be ruled out by evaluating iron parameters. Subsequently, a δ-globin mutation screening should be performed, especially in subjects from geographic areas with a high incidence of β-thalassemia carriers. δ-Thalassemia (OMIM No. 142000) resulting from mutations on the HBD gene usually has no clinical consequences, but it may cause a reduced rate of hemoglobin A2 (HbA2) [1, 2]. Human HbA2 (α2δ2), which contains δ-globin, represents a minor fraction of the Hb found in human adults. In normal individuals, it constitutes between 2.5 and 3.3% of the total adult Hb content as measured by high-performance liquid chromatography [3]. Although genetic defects (δ-thalassemia o HbA2 variants) that decrease HbA2 levels (2% in heterozygote or ≤0.6% in homozygote subjects) do not affect health, they can Received: June 22, 2017 Accepted after revision: November 6, 2017 Published online: January 13, 2018