Missed Diagnosis of α-Globin Gene Cluster Duplication in Prenatal Screening: Identified Incidentally by Invasive Testing

Excerpt

The methodology most often used in the preliminary selection of thalassemia carriers in premarital or prenatal screening is an integrated evaluation of red blood cell (RBC) parameters and hemoglobin (Hb) Variants. The mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCH) are determined by full blood count test. The quantitation of structural Hb variants is also used for atypical thalassemia or abnormal hemoglobins. Couples where both members are carriers of the same thalassemia trait are considered as at high risk for having an offspring with severe thalassemia syndromes. However, one of critical problems in carrier screening is the identification of the α-globin gene duplication, which by interacting with typical β-thalassemia may result in clinical features of severe β-thalassemia syndrome such as β-thalassemia intermedia (β-TI) or β-thalassemia major (β-TM). …