Oner C, Oner R, Gürgey A, Altay C
Hacettepe University, Faculty of Medicine, Department of Pediatrics, Ankara, Turkey.
Br J Haematol. 1995 Feb;89(2):306-12. doi: 10.1111/j.1365-2141.1995.tb03305.x.
In a 2.5-month-old infant with beta-thalassaemia major, DNA analysis of the gamma-beta region revealed homozygosity for two large deletions removing the entire psi beta and beta regions including their 5' promoter regions but leaving the delta gene intact. The downstream deletion was predicted to be 7.6 kb in length extending from a point 1.5 kb on the 3' side of the delta-globin gene to about 1.8 kb on the 3' side of the beta-globin gene. The upstream deletion, which was also about 7.6 kb, extended from a point 1.5 kb on the 5' side of the psi beta-globin gene to about 4.5 kb on the 3' of the psi beta gene. The delta-globin gene was intact. From the phenotypic expression of the disease it is concluded that removal of the psi beta gene probably prevents derepression of the gamma gene that has previously been observed in the absence of the promoter region of the beta gene and the switch mechanism from gamma to beta gene expression may take place earlier than expected.
在一名2.5个月大的重型β地中海贫血婴儿中，对γ-β区域进行DNA分析发现，存在两个大的缺失纯合子，这些缺失去除了整个ψβ和β区域，包括它们的5'启动子区域，但δ基因保持完整。下游缺失预计长度为7.6 kb，从δ珠蛋白基因3'侧1.5 kb处延伸至β珠蛋白基因3'侧约1.8 kb处。上游缺失也约为7.6 kb，从ψβ珠蛋白基因5'侧1.5 kb处延伸至ψβ基因3'侧约4.5 kb处。δ珠蛋白基因是完整的。从该疾病的表型表达可以得出结论，ψβ基因的缺失可能阻止了γ基因的去抑制，此前在β基因启动子区域缺失的情况下曾观察到这种去抑制现象，并且从γ基因到β基因表达的转换机制可能比预期发生得更早。
