Frequency of alpha thalassemia carriers detected in Tehran premarriage screening using molecular techniques

Based on the previous researches performed in Iran and worldwide، there is a significant number of subjects carrying alpha-thalassemia gene defect. Therefore، we aimed to assess its frequency amongst a random population selected from premarriage couples who entered the national prevention program of β -thalassemia major at Tehran. Blood samples were collected from 625 randomly selected individuals following obtaining written informed consent through eight cooperating primary health care centers (PHC) in Tehran. Primarily، CBC testing was performed. Subsequently، blood samples underwent DNA extraction and gene-specific amplification using ARMS PCR and Multiplex Gap PCR followed by DNA sequencing of negative samples to identify potentially missed alpha-globin gene mutations. According to CBC results، 147 individuals were considered normal; 479 remaining blood samples underwent molecular assessment which revealed that 95 samples possessed a minimum of one deletional mutation in the alpha-globin genes، resulting in a frequency of 19. 83% in the tested population (CI 95%; 11. 81-27. 85). Furthermore، 50 samples with normal hematological indices (MCH>27، MCV>80) were tested for triplication mutation and revealed to be negative. It has previously been established that Multiplex Gap PCR is capable of detecting 65% of alpha globin gene defects in blood samples with abnormally low hematological indices (MCH<27، MCV<80). Hence، using bio-informatic techniques with generalization of our results to the entire population of Tehran showed the true frequency of alpha-globin gene defect to be actually 29. 90% (CI 95%; 22. 40-37. 40) at the population level.