Abnormal hemoglobins associated with the beta-globin gene in Antalya province, Turkey

Aim: Abnormal hemoglobins are the most common hemoglobinopathies after beta-thalassemia in the world. More than 40 abnormal hemoglobin variants have been reported in the Turkish population. Therefore, it is one of the target areas for carrier screening. In our study, we aimed to screen the abnormal hemoglobins that cause clinical thalassemia in the Antalya population. Materials and methods: The present study identified the abnormal hemoglobins associated with the beta-globin gene using different molecular genetic techniques following high performance liquid chromatography (HPLC) results. We studied 972 postnatal and 361 prenatal cases (total: 1333 cases, 2666 chromosomes) with the disorder from 1998 up to July 2008. DNA extraction from peripheral blood, chorionic villi samples (CVS), amniotic cells, and cord blood samples was carried out using standard procedures. Following polymerase chain reaction (PCR) and amplification of the beta-globin gene, allele refractory mutation system (ARMS), reverse dot blot hybridization (RDBH), Nanochip, and DNA sequencing were performed to identify the mutations. Variable number of tandem repeats (VNTR) analysis was used for elimination of maternal contamination in prenatal diagnosis. We identified and characterized abnormal hemoglobin variants with novel and rare beta-thalassemic mutations. Results: Seven different abnormal hemoglobins were found in Antalya province, Turkey, namely Hb Antalya, Hb Tyne, HbS, Hb G-Coushatta, HbE, Hb Knossos, and Hb D-Los Angeles. Conclusion: Some of the abnormal hemoglobin variants found are unstable and some of them cannot be detected by simple electrophoretic examinations. Our findings suggest that abnormal hemoglobins are more frequent than expected among the other abnormal hemoglobins found in Turkey, and it is important both to perform prenatal diagnosis and to give genetic counseling for abnormal hemoglobins to families at risk for thalassemia.