A Novel G ? A ?(dß) 0 -Thalassemia with a 27 kb Deletion.

A new G γ A γ(δβ) 0 -thalassemia (thal) was found in six unrelated Japanese individuals, and characterized by a method employing only polymerase chain reaction (PCR) and direct sequencing. This G γ A γ(δβ) 0 -thal mutation has removed a fragment of about 27 kb of DNA, that starts approximately 2.8 kb downstream of the A γ-globin gene and ends in the L1 repeat sequence, 7.0 kb downstream of the β-globin gene. The 5′ breakpoint is similar to that of the previously reported Japanese G γ A γ(δβ) 0 -thal (called here Jpn type 1 for convenience). However, the 3′ endpoint is quite different. This new Japanese δβ-thal, designated as Japanese type 2 (Jpn type 2), shows a deletion rather similar to Turkish type 3 δβ-thal but with 5′ and 3′ breakpoints located inside the deletion of Turkish type 3. A mutation-specific gap PCR was designed to diagnose patients with the Jpn type 2 G γ A γ(δβ) 0 -thal. The identified carriers exhibited a thalassemia minor. [ABSTRACT FROM AUTHOR]