中国南方α地中海贫血基因突变型研究

为了进下完善和建立一套筛查我国α地中海贫血基因突变型的方法，研究我国南方两广地区α地中海贫血突变类型及分布情况，采用Gap-PCR，nested-PCR，PCR-SSCP，4P-ASPCR及序列分析等方法，对356例临床初诊为标准型和静止型α地中海贫血患和78例血红蛋白H(HbH)病患进行基因筛查。结果表明：356例标准型和静止型α地中海贫血患中发现-SEA/αα295人（82.87％），αα/α-α^3.71人（0.28％），αα/α-α^4.2 3人（0.84％）αα/αα^CS3人（0.84％），αα/αα^QS1人（0.28％）和αα/α^Westmeadα2人（0.56％），没有发现-α4.2和-α3.7的纯合子患；78例HbH病患中-SEA/αα^-3.7 29人（37.2％），-SEA/αα^-4.2 20人（25.6％），-SEA/αα^CS 19人（24.3％），-SEAαα^QS 2人（2.6％）。在8例未能确定基因突变类型的HbH患中，2例广西籍HbH患的α2基因第65密码子（第二外显子）有一同义突变CD65(GCC→GCG)。它与HbH病表型究竞竟有无关系，抑或是DNA单核苷酸多态位点（SNPs），有待进一步研究证实。在方法学方面，本研究进一步完善了以PCR为基础的基因诊断方法，建立了一种改进的检出非缺失型点突变的4P-ASPCR方法，能准确、快速地用于诊断我国常见的缺失型和非缺失型α地中海贫血突变基因。结论：我国α地中海贫血的基因背景比较复杂，不同地区点突变类型、频率及其发病机理等仍需进一步研究。本研究对进一步调整我国南方地区α地中海贫血基因诊断和产前基因诊断策略，有效地防止该病患儿的出生具有重要意义。

Study on Gene Mutations of α-Thalassemia in the South of China

There is a high prevalence of thalassemia in the South of China. To explore the genotype of alpha-thalassemia as well as the distribution of alpha globin gene mutation in the South of China, 356 patients with heterozygote alpha(+) thalassemia, heterozygote alpha(0) or homozygote alpha(+) thalassemia and 78 patients with HbH were analyzed. The gene diagnosis methods including Gap-PCR, nested-PCR, PCR-RE, PCR-SSCP, 4P-ASPCR and DNA sequence analysis were used. The results showed that among 356 patients, 295 patients with --SEA/alphaalpha (82.87%), 1 patient with alphaalpha/alpha-alpha(3.7) (0.28%), 3 patients with alphaalpha/alpha-alpha(4.2) (0.84%), 3 patients with alphaalpha/alpha(CS)alpha (0.84%), 1 patient with alphaalpha/alphaalpha(QS) (0.28%) and 2 patients with alphaalpha/alpha(Westmead) alpha (0.56%) were found. The homozygote with -alpha(4.2) or -alpha(3.7) was not found. In 78 patients with HbH, 29 patients with --SEA/alphaalpha(-3.7) (37.2%), 20 patients with --SEA/alphaalpha(-4.2) (25.6%), 19 patients with --SEA/alphaalpha(CS) (24.3%), 2 patients with --SEA/alphaalpha(QS) (2.6%) were detected, and other remaiming 8 patients were needed to be defined. Among the non-defined 8 patients, the synonymous mutation with C-->G transversion (GCC-GCG) at codon 65 in the exon 2 of alpha 2-globin gene was detected in 2 unrelated HbH patients came from Guangxi province. Whether it correlated with the phenotype of HbH disease or it is only a single nucleotide polymorphism site (SNPs), should be confirmed in the future. In addition, a set of gene diagnosis methods based on PCR to screen deletion and non-deletion genotypes of alpha-thalassemia in Chinese was improved. A new method, 4P-ASPCR, to detect Hb CS and Hb QS was also developed. The method was verified to be more accurate, time-saving and economic. In conclusion, the genotypes of alpha-thalassemia in Chinese are very complicated, the genotypes of alpha-thalassemia in Chinese need to be further studied, the results of this research probably have practical significance for the gene diagnosis or antenatal diagnosis of alpha-thalassemia in the South of China.