Analysis of human complement genes

本研究采用聚合酶链式反应和直接测序的方法，对人类补体系统C6、C7和C9基因的单核苷酸多态性进行了分析。一、C6基因的SNP如下：(1)外显子3的Nt413A→C(Aa98：Glu→Cys)。C6A和C6B/C6B2等位基因分别与Nt413A和Nt413C相关。(Ii)外显子10为Nt1674T→C(aa518：Cys→Cys)。(3)外显子13为Nt2145T→A(aa675：天冬氨酸氨基转移酶→谷氨酸)。(4)内含子2中的NT[357+32]G→A。日本人群的等位基因频率分别为*G=0.920和*A=0.080。(V)内含子3中的NT[5 0 3-78]G→A。对NT[35 7+32]和NT[5 0 3-78]的分析数据显示这两个座位之间存在连锁(或关联)。第二，C7基因的SNPs如下。(1)外显子9的Nt1166G→C。日本人的等位基因频率为*G=*C=0.5。(Ii)外显子4的Nt382T→C(aa106：Cys→arg)。Nt382C负责C7-5同种异型。亚洲人和欧洲人nt382C等位基因频率分别为：韩国人0.023，中国人0.046，日本人0.045。(3)内含子13的Nt1OG→A。日本人的等位基因频率为*G=0.822，*A=0.178。研究了R95X(C9基因第4外显子343C→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R95X是亚洲人群特有的等位基因。

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.