Detection of deletions/duplications in α-globin gene cluster by multiplex ligation-dependent probe amplification

Although Iran is one of the countries with a high frequency of thalassemia, few studies have been carried out on characterization of different mutations in the α-globin gene cluster. There are a proportion of patients suspected of having α-thalassemia according to hematological profile with no abnormalities identified by gap-PCR for the most common α-thalassemia deletions and no point mutations detected by amplification refractory mutation system and sequencing of the α-globin genes. So the aim of the present study was to identify the mutations at the α-globin cluster using the multiplex ligation-dependent probe amplification (MLPA) method in patients who were suspected to be carrier of α-globin gene mutations, but in whom no mutations were found by conventional techniques. Twenty patients whose mutations were not identified were selected. In addition, 10 and 5 samples were chosen as positive and negative controls, respectively. MLPA results demonstrated mutations in 15% of the cases undetected by the conventional methods. One case showed the deletion of regulatory element HS-40 and in two other cases α-triplication in α-genes was determined. The simplicity and high accuracy of MLPA make this method a complementary method along with gap-PCR for detecting common known and unknown deletions and duplications in the α-globin gene cluster.