Analysis of β/α globin ratio by using relative qRT-PCR for diagnosis of beta-thalassemia carriers

Current routine tests for premarital screening of β-thalassemia carriers are not applicable for diagnosis of rare atypical minor β-thalassemia cases. A more specialized laboratory evaluation for them is the measurement of β/α chain synthesis ratio with the assistance of radioactive amino acids. This method is also no longer routinely accessible. Consequently it is required to establish a rapid, trouble-free, and reliable method that encompasses all the cases of β-thalassemia carriers. Therefore we have determined β/α-globin mRNA ratio by applying relative qRT-PCR in various β-thalassemia patients.

Reticulocytes RNA extraction and subsequent cDNA synthesis were performed, followed by relative qRT-PCR for α- and β-globin chain genes and β-actin gene as an endogenous reference. β/α-Globin gene ratio was then evaluated with the Pfaffl method.

The mean of β/α ratio was 0.99, 0.81, 0.69, and 0.69 for normal population, minor, intermediate, and major β-thalassemia, respectively. Approximately 6% of cases with minor thalassemia RBC index and normal HbA2 and having a decreased β/α ratio were located in the minor β-thalassemia group. The mean of β/α mRNA ratio in normal individuals and minor β-thalassemia was significantly different with all other groups (P-value < 0.05). Nevertheless, there was no such association between β/α mRNA ratio in major and intermediate β-thalassemia.

According to the significant differences achieved, no overlapping between minor β-thalassemia and normal group, capability of diagnosing atypical minor β-thalassemia, and accessibility of this technique, we can declare that this method could be suggested as a routine premarital screening test for β-thalassemia carriers.