Clinical integration of red cell genotyping in children with β-thalassemia major: a prospective observational study

Blood group serology frequently fails in chronically transfused patients. Discrepancies between phenotype and genotype were reported for 51% of patients with β-thalassemia in 2013; however, red cell genotyping has not become clinical routine in Turkey. We evaluated the current situation by reviewing all patients with β-thalassemia major at the main pediatric hematology outpatient clinic in Ankara for 9 months. A commercial kit was used for red cell genotyping, along with nucleotide sequencing in 51 patients. A total of 1734 antigens were determined by genotyping and were compared with the phenotype on record for 306 antigens of the Rh and Kell systems. We found up to 3 discrepancies in reported phenotype vs the genotype in 25 patients (49%). Notably, the discrepancy rate has remained unchanged over the past 10 years. The 3 patients with alloantibodies received significantly more transfusions than those without (90 ± 9 vs 73 ± 19; P = .015). Patients with discrepancies trended toward hepatic iron overload (84% vs 58%; P = .071). Other clinical parameters, namely transfusion frequency, growth, ferritin levels, and liver and cardiac functions, were comparable between patients with and those without discrepancies. By assessing red cell genotyping for its possible clinical benefit, we immediately improved transfusion practice in half of the children with β-thalassemia major. The implementation of red cell genotyping, a high-throughput method with a rapid turnaround time, will enhance antigen matching. Our real-world data may serve as evidence in the decision processes for the implementation of genotyping in countries in which red cell genotyping is not yet common practice.