Alpha-thalassemia Mutations in Adana Province, Southern Turkey: Genotype-phenotype Correlation

To look over the distribution of the mutations in a large series from Adana province, Southern Turkey, and determine the genotype-phenotype correlation of the frequent mutations. Among the 2500 individuals with mild or moderate anemia, microcytosis, and normal iron levels that were referred to our Genetic Diagnosis Center, a population consisting of 539 individuals were included in the study and tested for alpha-thalassemia mutations by using reverse dot blot hybridization technique. Twelve different mutations were detected in 539 patients. Among the 12 different mutations found, the most frequent mutations were the -α(3.7) (63.3 %), --(MED) (11.7 %), --(20.5) (10.7 %), α2(IVS1(-5nt)) (3.9 %), and α2(polyA-2) (3.5 %). The most frequent genotypes were -α(3.7)/αα (35.8 %), -α(3.7)/-α(3.7)(18.9 %), -(20.5)/αα (11.5 %), and --(MED)/αα (10.4 %), respectively. There were statistically significant differences in hematological findings between -α(3.7)/-α(3.7) and --(MED)/αα, even though both have two mutated genes in the genotype. Our results show that alpha-thalassemia mutations are highly heterogeneous as well as deletional and -α(3.7) single gene deletion is particularly prevalent at Adana province in agreement to other studies from Turkey.