A novel four base-pair deletion within the Aγ-globin gene promoter associated with slight increase of Aγ expression in adult

Abstract

We studied a Chinese family and revealed 5.4% and 3.2% fetal hemoglobin (HbF) with advantageously Aγ type in the mother and the daughter, respectively, using alkali denaturation assay and urea-Triton-acrylamide gel electrophoresis and high-performance liquid chromatography. The father's HbF was less than 0.5%. Large deletion was not observed within the β-globin gene cluster by restriction endonulease mapping. Characterization by the polymerase chain reaction (PCR) and DNA sequencing demonstrated the mother is a homozygote with a novel four base-pair 'AAGC' (-226 to -223) deletion within the Aγ-globin gene promoter and the daughter is a heterozygote with this deletion. The deletion was not detected in the father. No any mutations were identified in the Gγ promoter of all the subjects studied. We propose that the small deletion is associated with the slight increase of Aγ gene expression in adult.