ß-Globin chain abnormalities with coexisting α-thalassemia mutations.

INTRODUCTION: The frequency of hemoglobinopathies is still high in Adana, the biggest city of the Cukurova Region that is located in the southern part of Turkey. Our aim was to identify the concomitant mutations in α- and ß-globin genes which lead to complex hemoglobinopathies and to establish an appropriate plan of action for each subject, particularly when prenatal diagnosis is necessary. MATERIAL AND METHODS: We studied the association between the ß-globin gene and α-thalassemia genotypes. The reverse hybridization technique was employed to perform molecular analysis, and the results were confirmed by amplification refractory mutation system (ARMS) or restriction fragment length polymorphism (RFLP) technique. RESULTS: We evaluated 36 adult subjects (28 female and 8 male; age range: 18-52 years) with concomitant mutations in their α- and ß-globin genes. The -α(3.7)/αα deletion was the commonest defect in the α-chain as expected, followed by α(3.7)/-α(3.7) deletion. Twenty-five of 36 cases were sickle cell trait with coexisting α-thalassemia, while seven Hb S/S patients had concurrent mutations in their α-genes. The coexistence of α(PolyA-2)α/αα with Hb A/D and with Hb S/D, which is very uncommon, was also detected. There was a subject with compound heterozygosity for ß-globin chain (-α(3.7)/αα with IVSI.110/S), and also a case who had -α(3.7)/αα deletion with IVSI.110/A. CONCLUSIONS: Although limited, our data suggest that it would be valuable to study coexisting α-globin mutations in subjects with sickle cell disease or ß-thalassemia trait during the screening programs for premarital couples, especially in populations with a high frequency of hemoglobinopathies.

ß-Thalassemia mutations and hemoglobinopathies in Adana, Turkey: results from a single center study.

INTRODUCTION: ß-Thalassemia and hemoglobinopathies are common genetic disorders in Turkey and in this retrospective study our aim was to determine the frequency of ß-thalassemia and hemoglobinopathies in Adana, which is one of the biggest cities located in the southern part of Turkey. MATERIAL AND METHODS: Data from 3000 individuals admitted to Seyhan Hereditary Blood Disorders Center in Adana were evaluated. The blood samples were collected into EDTA-containing tubes and hematological parameters were analyzed using an automatic cell counter. High performance liquid chromatography technique was used to determine the type of hemoglobin. Molecular screening of the ß-globin gene was performed with ß-Globin StripAssay. RESULTS: Of 3000 cases, 609 were diagnosed as ß-thalassemia or hemoglobinopathy. We have found that the rates of occurrence of ß-thalassemia and hemoglobinopathies are 13.46% and 6.83% respectively in this area. We have identified 18 different ß-thalassemia mutations and three separate abnormal hemoglobins: HbS, HbD Los Angeles, and HbE. In molecular analyses, ß-thalassemia gene mutations of IVSI.110 (G > A), codon 8 (-AA), IVSI.1 (G > A), IVSI.6 (T > C), -30 (T > A), IVSII.1 (G > A), codon 39 (C > T), codon 44 (-C), IVSI.5 (G > C), codon 5 (-CT), codon 8/9 (+G), IVSII.745 (C > G), codon 22 (7bp del), -101(C > T), codon 36/37 (-T), IVSI.15 (T > G), codon 6 (-A), -88 (G > A) were detected. CONCLUSIONS: Considering the high incidence of mutations that we have found, ß-thalassemia and hemoglobinopathies still seem to be a public health problem in Adana.

Nonsense ß-thalassemia mutation at codon 37 (TGG>TGA), detected for the first time in three Turkish cases.

Thalassemias are genetically heterogeneous group of disorders with reduced or absent production of globin. ß-Thalassemia major can be caused by homozygosity or compound heterozygosity for ß-globin gene mutation. Here we report, for the first time in Turkey, three cases who carry the nonsense ß-thalassemia (ß-thal) mutation at codon 37 (TGG>TGA; Trp→Stop) causing premature stop codon.

Molecular characterization of alpha-Thalassemia in Adana, Turkey: A single center study.

BACKGROUND/AIM: alpha-Thalassemia (alpha-thal) is a widespread genetic disorder throughout the world caused primarily by reduced synthesis of the alpha-globin chains, and it has been found at a high incidence in Turkey. Our aim in this study was to determine the frequency and molecular properties of alpha-thal in Adana, Turkey. MATERIAL AND METHODS: A total of 3,000 individuals comprising premarital couples or patients with anemia were screened between 2007 and 2008. Hematological parameters were analyzed using an automatic cell counter, and to detect the carriers of hemoglobin variants, high-performance liquid chromatography was used. Molecular screening of the alpha-globin gene was carried out by an Alpha-Globin StripAssay which is based on multiplex PCR for specific amplification. RESULTS: We have identified 225 cases with alpha-thal and found that the prevalence of alpha-thal is 7.5% in this area. In molecular analyses, the alpha-thal gene mutations alpha(3.7), alpha(4.2), --(MED), --(20.5), alpha(PA-2)alpha, alphaalphaalpha(anti-3.7), and alpha(PA-1)alpha were detected. CONCLUSION: Our results showed that the alpha-thal mutations represent a great heterogeneity and that the -alpha(3.7) deletion has the highest frequency in Adana.