Missed Diagnosis of β-Thalassemia Trait in Premarital Screening Due to Accompanying HbA2-Yialousa (HBD: c.82G>T)

The diagnosis of β-thalassemia (β-thal) trait is usually based on an elevated HbA2 fraction (3.5% to 8%). Co-inheritance of a δ-globin variant along with β-globin gene defects can interfere with the diagnosis of β-thal trait by causing normal HbA2 levels. In this report, we present an infant with β-thal major whose mother's β-thal trait was missed twice before due to an accompanying δ-globin mutation (HbA2-Yialousa; HBD: c.82G>T), resulting in a borderline HbA2 level. In an individual with microcytosis and hypochromia but an apparently normal HbA2 level, compound heterozygosity for a δ-globin mutation and a β-thal mutation should be remembered in the differential diagnosis.