Abe J, Kohsaka T, Tanaka M, Kobayashi N
Department of Immunology, National Children's Hospital Medical Research Center, Tokyo, Japan.
Nephron. 1993;65(1):17-22. doi: 10.1159/000187434.
Increased frequency of C4 gene deletions in IgA nephropathy and Henoch-Schönlein purpura nephritis. To determine the frequency of complement 4 (C4) deficiency among the patients with IgA nephropathy (IgAN) and Henoch-Schönlein purpura nephritis (HSPN), C4 and factor B protein allotypes and the DNA restriction fragment length polymorphism (RFLP) of C4, steroid 21-hydroxylase (21OHase), HLA DQ beta and DR beta chain genes were studied. Genomic DNA from 32 patients with IgAN, 24 patients with HSPN and 143 controls was digested with restriction enzyme TaqI or BamHI and subjected to Southern analysis. The frequency of C4 gene deletions was significantly increased in the patients (16.1 vs. 2.8%, p = 0.002). The serum C4 concentration in patients with C4 gene deletion was significantly lower than in patients without gene deletion (11.4 +/- 2.4 vs. 19.7 +/- 5.2 mg/dl, p = 0.001). DNA-RFLP typing of DQB/BamHI and DRB/TaqI showed increased frequency of 10.26 kb of D-DQw4/8/9 (87.5 vs. 64.5%, p = 0.004) and 5.22 kb of D-DR4 (66.1 vs. 41.7%, p = 0.03) among the patients. Segregation analysis showed that the association of the D-DQw4/8/9 and D-DR4 with the diseases was not responsible for the increased frequency of C4 gene deletion in the patients. The decreased concentration of C4 in sera in C4 gene-deleted patients might be directly involved in the pathogenesis of IgAN and HSPN.
IgA肾病和过敏性紫癜性肾炎中C4基因缺失频率增加。为确定IgA肾病（IgAN）和过敏性紫癜性肾炎（HSPN）患者中补体4（C4）缺陷的频率，研究了C4和B因子蛋白同种异型以及C4、类固醇21-羟化酶（21OHase）、HLA DQβ和DRβ链基因的DNA限制性片段长度多态性（RFLP）。用限制性内切酶TaqI或BamHI消化32例IgAN患者、24例HSPN患者和143例对照的基因组DNA，并进行Southern分析。患者中C4基因缺失的频率显著增加（16.1%对2.8%，p = 0.002）。C4基因缺失患者的血清C4浓度显著低于无基因缺失患者（11.4±2.4对19.7±5.2mg/dl，p = 0.001）。DQB/BamHI和DRB/TaqI的DNA-RFLP分型显示患者中10.26kb的D-DQw4/8/9（87.5%对64.5%，p = 0.004）和5.22kb的D-DR4（66.1%对41.7%，p = 0.03）频率增加。分离分析表明，D-DQw4/8/9和D-DR4与疾病的关联并非患者中C4基因缺失频率增加的原因。C4基因缺失患者血清中C4浓度降低可能直接参与了IgAN和HSPN的发病机制。
