Variants of the ST6GALNAC2 promoter influence transcriptional activity and contribute to genetic susceptibility to IgA nephropathy.
Li GS, Zhu L, Zhang H, Lv JC, Ding JX, Zhao MH, Shen Y, Wang HY
Renal Division, Department of Internal Medicine, Peking University First Hospital, Beijing, China.
IgA nephropathy (IgAN) is a polygenic disorder. Increasing evidence has implicated that aberrant glycosylation of IgA1 molecules, including alpha2,6 sialic acid [?] defects, are involved in the pathogenesis of IgAN. In the present study, we designed an association study to investigate polymorphisms of two important genes, ST6GALNAC2 and NEU1, which are involved in the sialylation of the IgA1 molecule, in the susceptibility to IgAN. A total of 670 patients with histologically proven IgAN and 494 healthy controls were enrolled. Screening of SNPs in the coding and promoter regions of the ST6GALNAC2 and NEU1 genes was performed by sequencing. ST6-SNP1 (c.-988A>G), ST6-SNP2 [rs3840858:D>I(CGGC), c.-450_-449insCGGC], ST6-SNP3 (rs1867561:C>G, c.-135C>G), and ST6-SNP7 (rs2304921:G>A, c.186+12G>A) in the ST6GALNAC2 gene were selected as tagging SNPs. Functional evaluations of targets were assayed by luciferase activity. The alpha2,6 sialic acid [?] contents of serum IgA1 in 497 patients were analyzed. Our results demonstrated that the frequency of haplotype ADG in the promoter region of ST6GALNAC2 was significantly higher in IgAN patients than that in controls (p=0.0069; odds ratio [OR]=1.36; 95% confidence interval [CI], 1.08-1.72). Furthermore, the ADG haplotype was associated with the deficient degrees of alpha2,6 sialic acid [?] of IgA1 molecules in IgAN patients (r=0.408, p=0.0035). The ADG haplotype conferred significantly reduced promoter activity compared with the most common haplotype GDG in vitro (196.43+/-21.55 vs. 258.41+/-46.25; p=0.002). In the present study, we identified for the first time the ADG haplotype in the ST6GALNAC2 gene as a functional regulatory variant that may contribute to the genetic susceptibility in a subset of patients in whom the desialylation of IgA1 molecules was the main causative pathogenesis of IgAN.
Hum. Mutat. (2007)
PMID: 17480010 Fulltext – Related articles – Download citation