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.