A Novel ^Gγ^Aγ(δβ)⁰-Thalassemia with a 27 kb Deletion

Abstract

A new ^Gγ^Aγ(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 ^Gγ^Aγ(δβ)⁰-thal mutation has removed a fragment of about 27 kb of DNA, that starts approximately 2.8 kb downstream of the ^Aγ-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 ^Gγ^Aγ(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 ^Gγ^Aγ(δβ)⁰-thal. The identified carriers exhibited a thalassemia minor.

• Thalassemia (thal)
• δβ-Thal
• Gene deletion
• Polymerase chain reaction (PCR)
• Gap PCR
• Gene dosage
• Quantitative PCR