Globin chain synthesis for differential diagnosis of β thalassemia from α thalassemia carriers

Background and ObjectivesGlobin chain synthesis and DNA analysis are among complementary tests for thalassemia diagnosis. Nowadays, DNA analysis is the only definitive method for diagnosis of suspected carriers. Despite the complexity of this heterogenic disease which is attributed to mutations in gene regulation sites or unknown mutations, globin chain synthesis has maintained its significant role in identifying different kinds of thalassemia. As a result, besides the routine application of this method, we decided to determine the ranges of α/β ratio values in different kinds of thalassemia. Materials and Methods In this experimental study 214 cases were divided into the control (51 cases), minor β thalassemia (24 cases), mild α (α thal. 2) thalassemia (68 cases), severe α (α thal. 1) thalassemia (44 cases), Hemoglobin H disease (6 cases), silent β (type II) thalassemia (14 cases), δβ thalassemia (5 cases), and αδβ thalassemia (2 cases) groups. CBC, hemoglobin electrophoresis using acetate cellulose paper in alkaline pH, hemoglobin A2 measurement by column chromatography, reticulocytes percentage, hemoglobin H, RBC morphology, and globin chain synthesis were performed on each group.ResultsSignificant differences were observed in mean values of RBC, hemoglobin, hematocrite, MCV, MCH, MCHC, α/β ratio in α and β thalassemia cases as compared with the control group. High prevalence of α thalassemia was observed among suspected individuals (55.2% of different kinds of α thalassemia vs. 9.8% of different kinds of atypic β thalassemia) as compared with atypic β thalassemia.ConclusionsThe mean value of α/β ratio achieved in this study was similar to the others, but with a greater standard deviation. Because of this, there exists a wider range of α/β ratio. This width of range made overlaps in different and adjacent groups. Therefore, α/β ratio cannot be used by itself to firmly diagnose the type of thalassemia. As a result, for accurate diagnosis to be made, besides considering patient's ethnicity and clinical features, it is necessary to assess the results of CBC, hemoglobin electrophoresis pattern analysis, globin chain synthesis, familial tests, and DNA analysis.