Abstract

  Background and Objectives

  There is a large number of couples who are considered potential carriers of alpha or beta-thalassemia. The exact determination of gene defect for thalassemia carriers is essential for premarital screening genetic counseling. In this study, we conducted a molecular study of those suspected of carrying alpha-thalassemia mutated genes in order to detect potential deletional and non-deletional mutations in the alpha globin gene cluster.

  Materials and Methods

  In this study, those suspected of having mutation in alpha-globin gene cluster with MCV < 80 fl, MCH < 27 pg, normal serum iron, and HbA₂ were selected from those referred to Pasteur Institute of Iran. Four common deletional mutations and non-deletional mutations were studied using multiplex gap-PCR, ARMS-PCR, and direct sequencing.

  Results

  One hundred and forty samples with above criteria entered the study with 126 (90%) cases showing at least one mutation. Study of 4 common deletional mutations using multiplex gap-PCR revealed at least one deletion in 99 (70.71%) cases. Non-deletional mutations were found using ARMS-PCR or direct sequencing in 27 (19.28%) cases. Nine different mutations were found in the samples with –α^3.7 being the most common deletion in 100 (35.71%) alleles out of 280 studied chromosomes followed by -α5^nt in 25 (8.93%) alleles as the next most common.

  Conclusions

  We used direct sequencing to characterize more suspected carriers of alpha thalassemia. However, using other methods like real-time PCR and multiplex ligation-dependent probe amplification (MLPA) for gene dosage study of alpha-globin gene cluster could help find other non-common deletions.

  Key words :

  Abstract

 Background and Objectives

 There is a large number of couples who are considered potential carriers of alpha or beta-thalassemia. The exact determination of gene defect for thalassemia carriers is essential for premarital screening genetic counseling. In this study, we conducted a molecular study of those suspected of carrying alpha-thalassemia mutated genes in order to detect potential deletional and non-deletional mutations in the alpha globin gene cluster.

 Materials and Methods

 In this study, those suspected of having mutation in alpha-globin gene cluster with MCV < 80 fl, MCH < 27 pg, normal serum iron, and HbA₂ were selected from those referred to Pasteur Institute of Iran. Four common deletional mutations and non-deletional mutations were studied using multiplex gap-PCR, ARMS-PCR, and direct sequencing.

 Results

 One hundred and forty samples with above criteria entered the study with 126 (90%) cases showing at least one mutation. Study of 4 common deletional mutations using multiplex gap-PCR revealed at least one deletion in 99 (70.71%) cases. Non-deletional mutations were found using ARMS-PCR or direct sequencing in 27 (19.28%) cases. Nine different mutations were found in the samples with –α^3.7 being the most common deletion in 100 (35.71%) alleles out of 280 studied chromosomes followed by -α5^nt in 25 (8.93%) alleles as the next most common.

 Conclusions

 We used direct sequencing to characterize more suspected carriers of alpha thalassemia. However, using other methods like real-time PCR and multiplex ligation-dependent probe amplification (MLPA) for gene dosage study of alpha-globin gene cluster could help find other non-common deletions.

 Key words : alpha-Thalassemia, mutation, PCR, Iran