Analysis of human complement genes

本研究采用PCR技术和PCR直接测序技术对人补体系统C6、C7和C9基因的单核苷酸多态性（SNP）进行了分析。I. C6基因中的SNP如下：（i）外显子3中的Nt 413 A →C（aa 98：Glu→Cys）。同种异型C6 A和C6 B/C6 B2分别与nt 413 A和nt 413 C相关。(ii)Nt1674 T →C（aa518：Cys→Cys）。(iii)外显子13中的Nt 2145 T →A（aa 675：Asp→Glu）。在同种异型B（纯合子）的样本中，在nt 2145处发现T和A，表明存在两种亚型的C6 B同种异型。(iv)内含子2中Nt[357+32]G→A。用限制性内切酶HinfI对nt[357+32]的SNP进行PCR-RFLP分析。日本人群的等位基因频率为 *G=0.920和 *A=0.080。(v)内含子3中的Nt[503-78]G→A。nt[357+32]和nt[503-78]的分析数据表明两个位点之间存在连锁（或关联）。二. C7基因中的SNP如下。(i)Nt 1166 G →C在外显子9中。用限制性内切酶DdeI通过PCR-RFLP分析该SNP。日本人的等位基因频率为 *G=*C=0.5。(ii)外显子4中Nt 382 T →C（aa 106：Cys→Arg）。Nt 382 C负责C7-5同种异型。亚洲和欧洲人群中nt 382 C的等位基因频率分别为：韩国人0.023，中国人0.046，日本人0.045。在泰国和意大利人群中未发现Nt 382 C;（iii）内含子13中的Nt 1 OG →A。用限制性内切酶Hin 1 I通过PCR-RFLP分析该SNP。日本人的等位基因频率为 *G=0.822和 *A=0.178。三.研究了R95 X（C9基因第4外显子nt 343 C →T）等位基因在4个亚洲人群和2个欧洲人群中的分布，结果表明R95 X为亚洲人群特异性等位基因。

Single nucleotide polymorphisms (SNPs) in C6, C7 and C9 genes of the human complement system have been analyzed by PCR-based methods and PCR direct-sequencing in the present study. I. SNPs in the C6 gene are as follows, (i) Nt413A→C (aa98:Glu→Cys) in exon 3. Allotypes C6A and C6B/C6B2 are associated with nt413A and nt413C, respectively. (ii) Nt1674T→C (aa518:Cys→Cys) in exon 10. (iii) Nt2145T→A (aa675:Asp→Glu) in exon 13. Both T and A at nt2145 were found in the sample with allotype B (homozygote), suggesting the existence of two subtypes of C6B allotype. (iv) Nt[357+32]G→A in intron 2. The SNP of nt[357+32] was analyzed by PCR-RFLP with restriction enzyme HinfI. Allele frequencies in a Japanese population were *G=0.920 and *A=0.080. (v) Nt[503-78]G→A in intron 3. The analysis data of nt[357+32] and nt[503-78] showed the linkage (or association) between the two loci. II. SNPs in the C7 gene are as follows. (i) Nt1166G→C in exon 9. This SNP was analyzed by PCR-RFLP with restriction enzyme DdeI. The allele frequencies in Japanese were *G=*C=0.5. (ii) Nt382T→C (aa106:Cys→Arg) in exon 4. Nt382C is responsible for C7-5 allotype. The allele frequency of nt382C in Asian and European populations were; Koreans 0.023, Chinese 0.046, and Japanese 0,045. Nt382C was not found in Thai and Italian populations, (iii) Nt1OG→A in intron 13. This SNP was analyzed by PCR-RFLP with restriction enzyme Hin1I. The allele frequencies in Japanese were *G=0.822 and *A=0.178. III. Distribution of R95X (nt343C→T in exon 4 of C9 gene) allele in 4 Asian and 2 European populations was studied, and the results showed R95X was an Asian population-specific allele.