β地中海贫血杂合子基因突变及Gγ珠蛋白基因-158位点SNP与Hb F的关系

目的　探讨 β地中海贫血 (简称 β地贫 )杂合子基因突变类型和 Gγ珠蛋白基因启动子 - 15 8位点 (Gγ- 15 8)单核苷酸多态性与胎儿血红蛋白 (fetal hemoglobin,Hb F)水平的关系。方法　抗碱 -比色法测定 Hb F水平 ;PCR-寡核苷酸斑点杂交法检测β地贫基因型 ;限制性内切酶 Xmn 消化经 PCR扩增的Gγ基因启动子 DNA片段 ,分析Gγ- 15 8位点的单核苷酸多态性。结果　 6 3例受检的轻型β地贫中 15例 Hb F≥ 2 % (2 .0 6 %～ 10 .4 4 % )。共检出 6种β地贫基因突变 ,分别是 :CD4 1/42 (- TTCT)、CD17(A→T)、nt- 2 8(A→ G)、CD71/72 ( A)、IVS- II- 6 5 4 (C→ T)、IVS- I- 1(G→ T)。 CD4 1/42、CD17、CD71/72、IVS- II-6 5 4的杂合子在 15例 Hb F升高组和 4 8例 Hb F正常组各自所占比例相同。 6 3例个体中有 10例为Gγ-15 8(C→T)突变的杂合子 ,总检出率为 15 .9% ;其中 15例高 Hb F个体中检出 8例 (检出率 5 3.33% ) ,HbF正常的 4 8例检出 2例 (检出率 4 .17% ) ,两组检出率差异有显著性 (P<0 .0 0 1)。结论　 β地贫基因突变CD4 1/42、CD17、CD71/72、IVS- II- 6 5 4与 β地贫杂合子的 Hb F水平无关 ;而 Gγ- 15 8(C→ T)突变与广西地区 β地贫杂合子 Hb F升高密切相关。

β-thalassemia mutations and single nucleotide polymorphism at -158 of Gγ-globin gene associated with altered levels of Hb F in β-thalassemia heterozygotes

OBJECTIVE: To investigate the relationship of beta-thalassemia mutations and the single nucleotide polymorphism(SNP) at position -158 of (G)Gamma-globin gene to the altered levels of fetal hemoglobin(Hb F) of beta-thalassemia heterozygotes. METHODS: Hb F was quantitated by alkali denaturation; beta-thalassemia mutations were determined by PCR-allelic specific oligonucleotide(PCR-ASO). The SNP at -158 was analyzed by amplification of (G)Gamma gene promoter fragments from the DNA, followed by Xmn I restriction enzyme digestion. RESULTS: Among 63 cases with beta-thalassemia trait, 15 had Hb F levels above 2% (2.06%-10.44%). Six beta-thalassemia mutations were observed in this study, namely CD41/42(-TTCT), CD17(A-->T), nt28 (A-->G), CD71/72(+A), IVS-II-654(C-->T) and IVS-I-1(G-->T). There was no difference in the incidence of beta-thalassemia heterozygotes of CD41/42, CD17, CD71/72 and IVS-II-654 between 15 cases with Hb F>/=2% and 48 cases with Hb F<2%. Ten (15.9%) heterozygotes of (G)Gamma-158(C-->T)were detected among 63 cases, and 8 of them (53.33%) belonged to the group of Hb F>/=2% while the remaining 2 cases (4.17%) were in the group of Hb F<2%. CONCLUSION: beta-thalassemia mutations of CD41/42, CD17, CD71/72, IVS-II-654 had no influence on Hb F levels, but (G)Gamma-158(C-->T) had a strong association with moderately increased Hb F levels in beta-thalassemia heterozygotes in the Guangxi area of China.