Abstract
The aim of this study was to determine the molecular spectrum and frequency of deletional and nondeletional α-thalassemia (α-thal) mutations and the genotype–phenotype correlation in common mutations in the Azeri population of Northwestern Iran. A total of 1256 potential carriers with microcytic and hypochromic anemia and normal Hb A2 levels (<3.5%) and without iron deficiency anemia plus three fetuses were identified. Multiplex gap-polymerase chain reaction (gap-PCR) and sequencing for α-thal mutations were carried out. In 606 individuals, the α-globin gene was normal, but in 650 persons (51.6%) and three fetuses, 10 different mutations were detected. The most frequent deletional genotypes were as follows: αα/–α3.7 (61.7%), –α3.7/–α3.7 (11.9%), αα/–α4.2 (4.6%), αα/– –MED (4.3%) and αα/–(α)20.5 (3.8%). The most frequent nondeletional genotypes were αα/αIVS-I (–5 nt)α (HBA2: c.95+2_95+6delTGAGG) and αα/αPoly A2α [polyadenylation signal (polyA2) (AATAAA>AATGAA); HBA2: c.*96G>A] with frequencies of 1.08% and 0.92%, respectively. Meanwhile, 7.71% of individuals with a proven β-thalassemia (β-thal) mutation were found to also carry an α-thal mutation. Persons having two functional α-globin genes showed lower mean corpuscular volume (MCV) and mean corpuscular hemoglobin (Hb) (MCH) values compared to those with one mutated α-globin gene, provided that they had normal β-globin genes. Overall, the incidence of α-thal was 2.7% in the Azeri population in Northwestern Iran. Our results showed that the variability of α-thal mutations are high in the Azeri population and that α-thal mutations are highly heterogeneous in both deletional and nondeletional genotype aspects.
Disclosure statement
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.