the frequency and importance of common α-globin gene deletions among β-thalassemia carriers in an iranian population

Background: β-thalassemia is the most common monogenic disorder in iran, and one of the challenges in the screening of the carriers is the coinheritance of α-thalassemia mutations. in the view of high prevalence of α-thalassemia mutations in many parts of the country, the aim of this study was to determine the carrier frequency of common alpha deletions, as a secondary modifier in clinical manifestations of beta thalassemia, in known beta-thalassemia carriers and some hematology parameter changes. methods: the study included families referred from different primary health care centers with microcytic hypochromic anemia [mcv<80fl; mch<27 pg] and a2>3.4%]. genomic dna was extracted from peripheral blood leukocytes by salting out method. for common β-globin gene mutation analysis, amplification refractory mutation system-polymerase chain reaction (arms-pcr) and for rare β-thal alleles, dna sequencing were used. also, for investigation of common α-globin gene cluster deletions (-α3.7, -α4.2, --med and -α20.5), multiplex gap-pcr was performed. results: among 227 β-thalassemia minor individuals studied, α-globin gene deletions were found in 43 cases: 37 heterozygote -α3.7 (16.3%), 5 homo -α3.7 (2.2%) and 1 -- med (0.44%). also, the co-inheritance of α-globin gene deletion and triplication was not found in the studied individuals. conclusion: although it is highly recommended that physicians and genetic counselors involved in the screening program of beta-thal major in the country consider this phenomenon because of high prevalence of this coinheritance, hematologic indices changes are very slight.