Genetic heterogeneity of beta-thalassemia at Cukurova in southern Turkey

beta -Thalassemia is the most common genetic abnormality causing health pro blems worldwide. Cukurova, in the southern part of Turkey, being on the Med iterranean, is in the thalassemic belt. Since there is no cure for the dise ase at present, the frequency of the mutation types of P-thalassemia must f irst be identified to aid in clinical follow-up and prenatal diagnosis. Car riers identified during a screening survey and patients referred to our lab oratory 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%, IV S-I-6 (T --> C) 5.7%, frameshift codon 8 (- AA) 5.7%, -30 (T --> A) 4.7%, I VS-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-I-5 (G --> C) 0.7%, frameshift codon s 8/9 (SG) 0.4%, frameshiftcodons 36/37 (-T) 0.4%, frameshift codons 22/23/ 24 (-AAGTTGG) 0.3%, IVS-I-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 fram eshift codons 82/83 (- G) mutations were seen in Turkey for the first time.