A novel frameshift mutation: deletion of C in codons 74/75 of the beta-globin gene causes beta zero-thalassemia in a Turkish patient

Coexistence of a novel beta-globin gene deletion (codons 81-87) with the codon 30 (G-->C) mutation in an Indian patient with beta0-thalassemia

We identified and characterized a novel beta0-thalassemia mutation due to the deletion of 22 bases from codons 81 through 87, found in a compound heterozygous state with codon 30 (G-->C) in a patient originating from West Bengal State, India. The deletion causes a shift in the reading frame of the coding sequence and creates a stop codon at position 81. Direct and inverted repeat sequences present in the deleted region might be involved in the origin of this mutation. The patient had moderate anemia and did not require blood transfusions (thalassemia intermedia).

A novel beta-thalassemia mutation in an Asian Indian

A novel 7 bp deletion in exon 2 of the beta-globin gene in a 9-year-old boy originating from the eastern part of India is described. This deletion causes a shift in the reading frame of the beta-globin coding sequences, and consequently, a premature translation termination due to the creation of a stop codon at position 86. A slipped strand mispairing during DNA replication repair is proposed as the potential mechanism in generating this small deletion.

Genetic heterogeneity of beta-thalassemia at Cukurova in southern Turkey

Beta-thalassemia is the most common genetic abnormality causing health problems worldwide. Cukurova, in the southern part of Turkey, being on the Mediterranean, is in the thalassemic belt. Since there is no cure for the disease at present, the frequency of the mutation types of beta-thalassemia must first be identified to aid in clinical follow-up and prenatal diagnosis. Carriers identified during a screening survey and patients referred to our laboratory were studied for this purpose. After routine hematological analysis molecular screening was performed by the amplification refractory mutation system and DNA sequencing. The frequency of the common mutations were: IVS-I-110 (G-->A) 57.3%, IVS-I-1 (G-->A) 8.3%, codon 39 (C-->T) 6.4%, IVS-I-6 (T-->C) 5.7%, frameshift codon 8 (-AA) 5.7%, -30 (T-->A) 4.7%, IVS-II-1 (G-->A) 3.4%, IVS-II-745 (G-->C) 2.8%, and frameshift codon 5 (-CT) 1.1%. Some rare mutations (1%) such as frameshift codon 44 (-C) 0.7%, frameshift codons 74/75 (-C) 0.7%, IVS-1-5 (G-->C) 0.7%, frameshift codons 8/9 (+G) 0.4%, frameshift codons 36/37 (-T) 0.4%, frameshift codons 22/23/24 (-AAGTTGG) 0.4%, IVS-1-130 (G-->C) 0.4%, IVS-1-5 (G-->T) 0.2%, -28 (A-->C) 0.2%, codon 15 (TGG-->TGA) 0.2%, and frameshift codons 82/83 (-G) 0.2%, were detected by sequence analysis. The codon 15 (TGG-->TGA) and frameshift codons 82/83 (-G) mutations were seen in Turkey for the first time.

Molecular and population genetic analyses of beta-thalassemia in Turkey

In this report we describe the molecular analysis of 795 chromosomes derived from unrelated Turkish beta-thalassemia and sickle cell anemia carriers identified in hematology clinics in Istanbul, Ankara, Izmir, Adana, and Antalya. The determination of the molecular pathology of 754 beta-thalassemia and 42 abnormal hemoglobin genes and analysis of the frequency distribution in six distinct regions of Turkey was accomplished. The experimental strategy, based on PCR amplification of the beta-globin gene, included dot-blot hybridization with 18 probes specific for the Mediterranean populations, denaturing gradient gel electrophoresis, and genomic sequencing. When the regional results are compared with the overall frequency of mutations in the country, it is observed that the frequencies in the western and southern parts of Turkey are in good accordance with the overall distribution, whereas the northern and eastern parts have a more region/population-specific profile with some rare mutations having a significantly high occurrence in these regions. Further evaluation of the data with respect to region- or population-dependent differences will contribute to a better understanding of the mechanisms leading to the marked genetic heterogeneity in Turkey, but could also be extremely valuable in facilitating rapid identification of mutations in families at risk for different hemoglobinopathies.

Biotechnological developments in Turkey

Turkey is a country not usually associated with industrial biotechnology. However, when current research potential in universities and other R & D centers and particularly contributions made to the international literature since the mid-1980s are taken into account, high-quality international-level work is now commonplace, especially in areas such as industrial microbiology, enzyme technology, biomaterials and biological wastewater treatment. Work in plant biotechnology is at a relatively early stage, but is expected to become a rapidly developing force in the near future. The present article documents current potential in Turkey, based on significant publications produced during the last 8 years.