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Objective: To explore the feasibility of applying autosomal single nucleotide polymorphisms (SNPs) on parentage testing., Methods: All SNP genotyping results of HapMap (r27) were downloaded from the website. With self-made computer programs, SNPs were extracted when their minor allele frequency (MAF) were ≥ 0.30 among all of the 11 HapMap populations. Ninety-six SNPs were chosen and integrated into the Illumina Goldengate bead arrays on the condition that no linkage disequilibrium was found between them. Three father-child-mother trios (9 samples in total) were tested with the arrays. Cumulative paternity index (CPI) was then calculated and compared with genotyping results using 15 short tandem repeats (STRs)(Identifiler(TM))., Results: Family 1 was found to have nine SNPs or seven STRs that did not conform to the Mendelian laws, Family 2 had 13 such SNPs or seven STRs, and Family 3 only had one such SNP but no STR. For Family 3, when all of the 96 SNPs were used in combine, the CPI was 1207, which had contrasted with the CPI by the 15 STRs, i.e., 355 869., Conclusion: When applied to paternity testing, the paternity exclusion (PE) value for a SNP is usually less than 1/3 of that of a STR. The proportion of SNPs not comforming to the Mendelian laws for the tested SNPs may not be as high as that of inconsistent STRs over all tested STRs. Because of the low mutation rate of a SNP, the CPI will be greatly reduced even if one SNP did not conform to the Mendelian laws. Therefore, highly accurate testing methods are required to reduce artificial errors when applying SNPs for paternity testing.

Objective: To set up the method for analyzing HLA-B gene polymorphism with PCR-RFLP, and to gain population data among northern Chinese Hans of HLA-B's restricted fragments after NlaIII digestion, and to achieve application in forensic medicine practice., Methods: Sample DNA was extracted by the phenol/chloroform extraction method, 943 bp-long fragments containing HLA-B exon 2 and 3 were got by PCR. The endonuclease NlaIII was applied to cut the PCR products into polymorphic fragments shorter than 943bp, then PAGE and silver staining were used to detect the digestion results, finally the digestion sites were assured by DNA sequencing., Results: Along 943bp-long PCR products, 14 length-different fragments, 20 kinds of fragment combinations were got and 6 cutting site were observed after NlaIII digestion., Conclusion: HLA-B gene was highly polymorphic among Chinese northern Hans. Even with only one endonuclease, 14 restricted fragments were got and the PIC was great. Such a HLA-B PCR-RFLP analysis will have values in forensic medicine applications.

Inflammatory bowel disease (IBD) includes two clinical subtypes: Crohn disease (CD) and ulcerative colitis (UC). The general prevalence is about 1.0-2.0 % in Western countries. It is predominantly regarded as a multifactorial disorder involving environmental factors and polygenic defects. The view was confirmed by a lot of evidences from clinical attributions and animal models, especially from epidemiological investigations. So the etiological study of IBD has been focused on searching for susceptibility genes by positional cloning, which consists of two steps: linkage analysis and association analysis. Linkage analysis has been an important method of searching for susceptibility genes to polygenic diseases as well as single-gene disorders. IBD, as a polygenic disease, has been widely investigated by linkage analysis for susceptibility gene since 1996. The paper reviewed 38 articles, which covered almost all original researches in relation to IBD and linkage analysis. So far, several loci, such as 16q, 12q, 6p and 3p, have been identified by the studies. The most striking is 16q12 (IBD1), which linked only with CD not UC in the majority of studies. Association analysis, as one essential step for positional cloning, is usually carried out by genotyping candidate genes selected by means of linkage analysis or other methods, for figuring out the frequencies of alleles and comparing the frequencies between IBD group and healthy control group to identify the specific allele. It has been established that IBD is implicated in immune disorder. So the studies were centered on the genes of NOD2/CARD15, HLA-II, cytokine, cytokine receptor and adhesion molecule. This paper reviewed 14 original articles on association between NOD2 and IBD that have been published since 2001. All results, with the exception of one report from a Japanese group, provide evidences that the three kinds of variants of NOD2 are susceptibility factors for IBD. This article also comprehensively analyzed 18 original researches of HLA gene polymorphism in IBD. We found extensive discrepancy among the conclusions and a novel hypothesis was put forward to explain the discordance. Most studies published recently on association between IBD and cytokine gene polymorphism were reviewed.