| The sequence of Human Genome Project (HGP) includes all the informations of the course of life of human beings. It will promote the advance of biology and medicine greatly in next century as a special control of groundback of life. For Human Genome Project planning digested human gene DNA sequence into many 150-200bp fragments, and reconstructed into the germ clone and to be sure the accuracy is over 99.9%. Single nucleotide polymorphism (SNP) provides the basis of the research of variations of human gene sequence. The sequence of Human Genome Project is a draft coming from a few people and it can reflect the stable aspects of human genome, but it can't reflect the varied aspects of human genome. SNP is a very efficient gene analyse tool and it can help us explore the relationships between some special sites and many diseases. The occurrence rate of SNP is 1SNP/kb. Mapping and constructing the SNP map can provide a complete description of all the genes. It is beneficial to elucidate the difference of phenotype and susceptibility to disease of individual person. On the basis of high density and high polymorphisms SNP map, genome scanning and association study are used to screen for more relative genes of complex diseases. It makes a great progress in mapping the susceptibility genes of polygenic disease. These studies will accelerate the pace of the description and translation of the sequence of Human Genome Project greatly.Schizophrenia is a common mental disorder with 1% of the life-time prevalence in the general population worldwide. Schizophrenia is mostly present special thinking, sense, feelings and behavior disorder. It brings heavy burden to society and family, so how to declare its mechanism is the most urgent important study filed. Epidemiological data demonstrate that schizophrenia is not a simple Mendelian disease, but it looks like a complex disease with a polygenic mechanism. At present, Genome-wide scanning shows the susceptibility genes linkage findings on some chromosome regions, such as 1q21-22, 5q22-23, 6p24-21, 8p22-21, 13q14-33 and 22q11-12 .Our study has focused on identifying the candidate susceptibility genes on the MHCâ…¡,â…¢ region of chromosome 6 using a family-based LD analysis. The family trios consist of healthy fathers, healthy mothers and affected offspring with schizophrenia. Technique route was followed in such a way that from positive region determined by genome scanning to gene map, and SNP-based LD map. The SNP-based LD map was constructed near the NOTCH4 gene and the TNXB gene. 8 SNPs were chosen in this region spanning 101365bp. SNPs were genotyped using PCR-based RFLP analysis. Genotyping data were put into the SPSS database. The Hardy-Weinberg (H-W) equilibrium was tested for genotype frequency distributions of SNPs using the goodness of fit test. The LD between paired SNPs was estimated with the EH program. The haplotype relative risk (HRR) test and the transmission/disequilibrium test (TDT) were applied to detect allelic association between an SNP and schizophrenia. Haplotypes consisting of two or more SNPs were tested by the program Transmit (Version2.5). To elucidate genetic heterogeneity, in addition, schizophrenic patients were sub-grouped based on their clinical symptoms and the genetic association between SNPs and clinical subgroups was then analyzed. Positive loci were replicated with different family trios to rule out the false positive results. A total of 120 family trios of Chinese Han decent, consisting of fathers, mothers and affected offspring with schizophrenia, were recruited. Patients were diagnosed as having schizophrenic illness by the ICD-10 criteria. Eight SNPs included SNP99 (rs8084), SNP100 (rs2143466), SNP101 (rs387071), SNP102 (rs367398), SNP103 (rs915894), SNP104 (rs422951), SNP108 (rs1009382) and SNP120 (rs520688). The following is the details of major results obtained in this study. 1. The H-W equilibrium:The goodness of fit test showed that genotype frequency distributions of 8 SNPs were not deviated from the H-W equilibrium,...
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