A novel (delta beta)(0)-thalassemia due to a approximately 30-kb deletion observed in a Turkish family.

A new deletion of the beta-globin gene cluster was characterized in a Turkish family. A 6-year-old male and his father were heterozygotes for this deletion. They presented with mild hypochromic microcytic anemia associated with elevated Hb F (15%) and normal Hb A2 levels (2.0%). This newly described Turkish type (delta beta)(0) thalassemia has a deletion of about 30 kb. The 5' breakpoint of this deletion starts approximately 1.5 kb downstream of an enhancer-like sequence of the A gamma-globin gene. The 3' endpoint is located in the L1 repeat sequence (Kpnl site) 3' to the beta-globin gene. The new deletion (Turkish type 3) is quite similar to that of the Indian (delta beta)(0)-thalassemia deletion in size and 5' breakpoint. However, the 3' endpoint in this new deletion is 2.5 kb shorter than the Indian type.