α/β-Globin mRNA ratio determination by multiplex quantitative real-time reverse transcription-polymerase chain reaction as an indicator of globin gene function

Objectives: Imbalance in α/β-globin chains is an important determinant of thalassemia disease severity. This study examined the relationship between α/β-globin mRNA ratio and disease severity in various thalassemia genotypes. Design and methods: α- and β-globin mRNA contents of red blood cells of 75 α- and 32 β-thalassemia subjects (5 with β0-thalassemia/Hb E) and 14 normal controls were measured using multiplex quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). The α/β-globin mRNA ratio of each sample was calculated based on the 2−ΔΔCT method. Results: A decrease of α/β-globin mRNA ratios in α-thalassemia subjects compared to normal controls correlated with the numbers of defective α-globin genes, whereas an increase of the ratios was observed in β-thalassemia. Subjects with β0-thalassemia/Hb E disease had the highest α/β-globin mRNA ratio, followed by β0-thalassemia trait and then β+-thalassemia trait, which correlated with decrease in severity of anemia. Coinheritance of α-thalassemia in β0-thalassemia/Hb E resulted in a more balanced α/β-globin mRNA ratio and an amelioration of the anemia. Conclusions: This study indicates that imbalance in globin gene expression, the major factor affecting clinical severity of thalassemia, could be demonstrated by measuring α/β-globin mRNA ratio, which was conveniently and accurately determined by qRT-PCR. In α-thalassemia, α/β-globin mRNA ratio correlated with the number of functional α-globin genes present, whereas in β-thalassemia, the ratio provided a good indicator of disease severity.