Molecular characterization of a novel form of (A gamma delta beta)zero
thalassemia deletion in a Chinese family
JW Zhang, WF Song, YJ Zhao, GY Wu, ZM Qiu, FN Wang, SS Chen and G Stamatoyannopoulos
Department of Biochemistry and Molecular Biology, Chinese Academy of
Medical Sciences, Beijing.
We have identified and molecularly characterized a novel deletion in the
beta-globin gene cluster that is associated with elevated fetal hemoglobin
in the adult. The propositus is a homozygote from the Yunnan province of
China. The deletion spans about 90 kb of DNA and removes the A gamma,
delta, and beta-globin genes. The 5' breakpoint of the deletion is located
about 0.13 kb upstream from the A gamma-globin gene, whereas the 3'
breakpoint is located about 66 kb downstream from the beta-globin gene,
about 13 kb upstream from the breakpoint of the Chinese (A gamma delta
beta)zero-thalassemia. Heterozygotes for this Yunnanese form of (A gamma
delta beta)zero-thalassemia express between 9% and 17% of fetal hemoglobin,
whereas the homozygote present with a mild anemia (Hb = 10.7 g/dl).
Comparison of the sites of 3' breakpoints of the Yunnanese and the Chinese
(A gamma delta beta)zero-thalassemia mutants is compatible with the
hypothesis that an enhancer element is located between the 3' breakpoints
of these two mutants. Juxta-position to the G gamma gene of this element
may be responsible for the efficient gamma-gene expression in the Yunnanese
mutant.
Volume 81,
Issue 6,
pp. 1624-1629,
03/15/1993
Copyright © 1993 by The American Society of Hematology
