广东地区地中海贫血致病基因的基因型及β珠蛋白基因多态性研究

Genotype of thalassemia genes and the polymorphism of β-globin gene in Cantonese

目的了解近年来广东地区人群中α、β珠蛋白基因的基因型分布，并对β珠蛋白基因的单核苷酸多态性（SNP）进行研究，为更准确地进行地中海贫血的遗传诊断提供理论依据。方法利用单管多重PCR检测3种5缺失型地中海贫血，采用反向杂交（RDB）／PCR技术检测α^CS、α^QS、α^WS 3种α非缺失型及中国人常见的18种β珠蛋白的基因突变，对454份广东籍受检者标本进行地中海贫血基因分型，对其中的142份标本进行变性高效液相色谱（DHPLC）分析和β珠蛋白全基因测序，分析广东地区人群β珠蛋白基因SNP。结果在438例基因分析确诊的地中海贫血患者中，α、β、αβ复合型地中海贫血分别为246、164和28例。246例5地中海贫血患者中，检出αα/--^SEA197例、αα／-α^3.7 20例、αα／-α^4.2 9例。164例β地中海贫血中，152例（92．7％）为杂合子，以CD41—42、IVS-Ⅱ-654、-28和CD17为主；8例（4．9％）为复合杂合子，4例（2．4％）为纯合子。DHPLC结合测序筛查B珠蛋白基因与RDB诊断结果一致，并发现9种SNP，其中IVS—Ⅰ-13G〉A、IVS-Ⅱ-310 T〉C未见报道。在检测标本中，有4种SNP频率较高，73．2％的患者同时合并其中3种SNP（rs713040、rs10768683、rs1609812）。结论在α地中海贫血中，主要以αα／--^SEA基因型为主；β地中海贫血以CD41—42、IVS—Ⅱ-654、-28、CD17为主要突变类型；β地中海贫血复合杂合子、纯合子及αβ复合型地中海贫血的频率较高。DHPLC结合β珠蛋白全基因测序可以快速、有效地检出常见β地中海贫血突变型。rs713040、rs10768683、rs7480526、rs1609812在筛查人群中频率较高。

Objective To understand the genotype of ct and β-globin, as well as the polymorphism of ^-globin gene in Cantonese in recent years, and to provide an effective genetic diagnosis for thalassemia （thal）. Methods The single-tube complex PCR was used to detect 3 types of deletional α-thal, reverse dot blotting （RDB）/PCR to detect 3 kinds of undeletional α-thal--α^CS, α^QS, α^WS and 18 kinds of β-thal mutations which were common in Chinese population. A total of 454 cases from Guangdong were undergone thai genotype genetic diagnosis. Among the 454 cases, 142 cases were selected to perform the single nucleotide polymorphisms （SNPs） analysis of β-globin gene by denaturing high-performance liquid chromatography （DHPLC） combining the whole gent sequencing. Results Of the 454 cases, 438 were diagnosed as thalassemia, including 246 of α-thal, 164 of β-thal and 28 of αβ-thal. In 246 α-thal cases, deletions were the dominant mutations, including 197 cases of αα/--^SEA, 20 of αα/-α^3.7 and 9 of αβ-α42. In 164 β-thal cases, heterozygntes accounted for 92.7% （152/164）, the main genotypes were CD41-42, IVS- Ⅱ-654,-28 and CD17, and the dual heterozygotcs and homozygotes accounted for 4.9% （8/164） and 2.4% （4/164）, respectively. The result of β-globin gene screening by DHPLC combining with sequencing was consistent with that of RDB. Moreover, we also found 9 kinds of SNP, in which 2 were unreported, the IVS- Ⅰ -13 G〉 A and IVS- Ⅱ -310 T〉C. In the tested samples, the frequency of 4 kinds SNP was high, among which 3 kinds SNPs-rs713040, rs10768683 and rs1609812 were carried together. Conclusion The dominant genotypes were αα/--^SEA in α-thal cases, CD41-42, IVS- Ⅱ -654, -28 and CD17 in β-thal. The frequency of β- thal heterozygotes, homozygotes and αβ-thal is high. DHPLC combining the whole β-globin gene sequencing can effectively detect the common β-thal mutation and even new mutations or SNPs. In Cantonese, the frequency of SNP rs713040, rs10768683, rs7480526 and rs1609812 of β-globin gene was high, and there may exist genetic linkage between rs713040, rs10768683 and rs1609812.