The G→A Mutation at Position +22 31to the Cap Site of theβ-Globin Gene as a Possible Cause for aβ-Thalassemia
作者:
ÖnerR.,
AgarwalS.,
DimovskiA. J.,
EfremovG. D.,
PetkovG. H.,
AltayC.,
GurgeyA.,
HuismanT. H.J.,
期刊:
Hemoglobin
(Taylor Available online 1991)
卷期:
Volume 15,
issue 1-2
页码: 67-76
ISSN:0363-0269
年代: 1991
DOI:10.3109/03630269109072485
出版商: Taylor&Francis
数据来源: Taylor
摘要:
We describe the occurrence of a chromosome with a G→A mutation at position +22 relative to the Cap site that was found in five patients withβ-thalassemia. All patients had a common type ofβ-thalassemia mutation on the second chromosome, namely the frameshift at codon 8 (-AA), the IVS-I-110 (G→A) and the IVS-II-1 (G→A) mutations. Theβgenes of two patients, including the 5′and 3′untranslated regions, were completely sequenced and no other mutations, except a few polymorphic sites, were observed. Dot-blot analyses failed to demonstrate this G→A mutation at +22 in nearly 400β-thalassemia chromosomes and 180 normal chromosomes. Hetero-zygotes have the features of a high Hb A2-β-thalassemia hetero-zygosity, although the hematological parameters might be less abnormal than observed in heterozygotes for the more commonβ-thalassemia mutations. The possibility has been presented suggesting that this mutation might impair the binding of mRNA to ribosomes. Another mutation in this segment of DNA, i.e. a C→G mutation at position +20, is observed exclusively on a chromosome which also carries the C→G mutation at IVS-II-745. It is postulated that the +20 C→G mutation accentuates theβ-thalassemia condition caused by the IVS-II-745 mutation; the mechanism might be similar to that suggested for the G→A at +22 mutation.
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