IgA肾病患者C1GALT1C1基因的体细胞突变筛查

Screening somatic mutation of C1GALT1C1 gene in IgA nephropathy

目的 探讨IgA肾病（IgAN）患者β1,3半乳糖转移酶的分子伴侣Cosme编码基因C1GALT1C1基因体细胞突变情况。方法 27例IgA肾病患者及19例正常健康对照作为研究对象。提取研究对象外周血基因组DNA,扩增C1GALT1C1基因的编码区,采用PCR产物直接测序的方法进行突变筛查。然后,分离其中15例IgA肾病患者及7例健康男性对照的外周血B淋巴细胞,提取DNA。对C1GALT1C1基因编码区进行扩增,PCR产物进行克隆,各挑选平均8～10个克隆进行体细胞突变筛查。结果 46例个体全血基因组DNA的PCR扩增产物测序发现,2例患者及1例健康对照存在外显子T393A变异,次等位基因频率（MAF）为6．9%[SNP数据库（dbSNP）报告为9．5%]。B淋巴细胞DNA序列分析显示,在22例个体（15例IgA肾病患者,7例健康对照）送检的总共202个克隆中,未发现新的突变和多态性位点。结论 C1GALT1C1基因编码区T393A多态位点在本研究人群中为唯一发现的多态性位点,其次等位基因频率（MAF）较既往报道略低。本研究尚未发现IgA肾病患者B淋巴细胞存在体细胞突变。

Objective To investigate somatic mutation of C1GALT1C1, a coding gene for molecular chaperone cosmc of β1,3 galactosyltransferase, in patients with IgA nephropathy（IgAN）. Methods Twenty-seven IgAN patients and 19 normal healthy controls were enrolled in the study. Firstly, the coding region of C1GALT1C1 was amplified by PCR from genomic DNA in peripheral blood and PCR products were directly sequenced. Meantime, DNA from peripheral blood B lymphocyte was extracted from 15 IgAN patients and 7 normal controls. The coding region of C1GALT1C1 was amplified from DNA in peripheral blood B lymphocyte, and then, PCR products were subcloned into PGEM-T vector. Total 202 clones, including average 8 to 10 clones per individual, were randomly selected for directly sequencing. Results T393A polymorphism in the coding region of C1GALT1C1 was found in 2 patients and 1 control from their peripheral blood genomic DNA. The minor allele frequency was 6.9%, which was a bit lower than that reported in dbSNP （9.5%）. No mutations or polymorphisms were found in total 202 clones from B lymphocyte DNA in 22 persons （15 patients and 7 controls）. Conclusions A polymorphism, T393A, in the coding region of C1GALT1C1 gene is identified in present study. Minor allele frequency is lower than that in previous report. Somatic mutation can not be found in B lymphocyte of patients with IgAN.