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

The diagnosis of ß-thalassemia (ß-thal) trait is usually based on an elevated HbA2 fraction (3.5% to 8%). Co-inheritance of a δ-globin variant along with ß-globin gene defects can interfere with the diagnosis of ß-thal trait by causing normal HbA2 levels. In this report, we present an infant with ß-thal major whose mother's ß-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 ß-thal mutation should be remembered in the differential diagnosis.