短串联重复序列HumFGA、D3S1359的法医学应用研究

对短串联重复序列（short tandem repeats，STR）的两个高多态位点HumFGA(human alpha fibrinogen，人类α-纤维蛋白原基因)、D3S1359的法医学应用进行研究，并通过实际检测案件统计结果进行评估。实验结果表明：两位点灵敏度高，分别为0.2、0.5ngDNA；同一性和可重复性均较理想；种属特异性好，常见动物未发现扩增产物，仅灵长类动物（黑叶猴和猕猴）有扩增条带；复合扩增体系效果良好；在352次减数分裂中，D3S1359未发现突变，HumFGA检测到1次，突变率为0.28％；实际案件统计和应用结果也显示两位点是多态性高，实用性强的两个遗传标记系统。HumFGA和D3S1359在法医学个人识别与亲子鉴定案例中有较大应用价值。     

胃癌D17S261和D17S799位点二核苷酸重复序列不稳定性的意义

目的研究二核苷酸重复序列不稳定性〔ＤＲＳＩ〕在胃癌发生中的作用及其临床意义．方法采用ＰＣＲ方法检测了Ｄ１７Ｓ２６１和Ｄ１７Ｓ７９９位点二核苷酸重复序列不稳定性．结果胃癌总ＤＲＳＩ发生率为３４％（１７／５０），其中高中分化腺癌ＤＲＳＩ阳性率（６６７％，１０／１５）显著高于低分化癌（１９４％，６／３１，Ｐ＜００１）；肠型胃癌ＤＲＳＩ阳性率（５５６％，１０／１８）显著高于胃型胃癌（２０％，６／３０，Ｐ＜００５），ＤＲＳＩ与胃癌部位、大小、浸润、分期、淋巴结转移无显著相关．结论ＤＲＳＩ在胃癌的发生中可能起重要作用．     

A highly variable STR at the D12S391 locus

A total of 103 fragments in the STR D12S391 locus were sequenced. 24 different alleles were found which can be grouped into 12 allelic classes based on the total number of repeats. The structure of this compund STR consists of blocks of (AGAT) and (AGAC) repeats with a consensus structure (AGAT)_8–l7 (AGAC)_6–10 (AGAT)_0–1. Whereas shorter alleles only have (AGAT) repeats, > 225 bp alleles are more complex, having two motifs (AGAT) and (AGAC). Population data showed that this to be a highly polymorphic STR with a heterozygosity of 0.9. This fact together with its simple structure make this STR very suitable for forensic and genetic purposes.     

Linkage studies and mutation analysis of the PDEB gene in 23 families with Leber congenital amaurosis.

The phenotype in the rd mouse is similar to the clinical presentation of Leber congenital amaurosis (LCA) in humans. Recently a nonsense mutation in the beta subunit of the cGMP phosphodiesterase (Pdeb) gene has been defined as the cause for the rd phenotype in the mouse and has raised the question as to whether mutations in the human PDEB gene might cause LCA. We have previously cloned and characterized the human homologue of the mouse Pdeb gene and have mapped it to chromosome 4p16.3. In this study, a total of 23 LCA families of various ethnic backgrounds have been investigated. Linkage analysis using highly polymorphic (CA)n microsatellites has excluded the PDEB gene as a cause for LCA in 6 families. In the remaining 17 families, we have searched for mutations in the 22 exons of the PDEB gene using single-strand gel electrophoresis (SSGE). Multiple exonic polymorphisms have been determined. However, no DNA changes in the PDEB gene have been identified in our study population which could be causative for the LCA phenotype.     

D4S1647、D6S2414基因座在中国汉族、蒙古族、藏族的遗传多态性

目的 调查D4S1647、D6S2414基因座在中国汉族、蒙古族、藏族群体中的遗传分布规律。方法 采集308份血及唾液标本应用PCR技术，扩增产物用非变性聚丙酰胺凝胶电泳分离，银染显色分析。结果 两位点各群体基因型频率分布均符合Hardy-Weinberg平衡，每一位点等位基因频率分布在各群体间无显著差异；通过对10个汉族家系的遗传模式分析，证实了两位点等位基因传递遵循孟德尔遗传规律。结论 D4S1647、D6S2414基因座在中国汉族，蒙古族，藏族群体均具有高度遗传多态性。     

Random coil conformation for extended polyglutamine stretches in aqueous soluble monomeric peptides

Several neurodegenerative diseases have been found to be strongly associated with proteins containing a polyglutamine stretch which is greatly expanded from approximately 20 glutamines in normal individuals to more than 40 in affected individuals. A conformational change in the expanded polyglutamine stretch has been suggested to form the molecular basis for disease onset. Model peptides containing polyglutamine tend to aggregate and become insoluble. We have synthesized readily water-soluble monomeric peptides by flanking polyglutamine stretches with sequences rich in alanine and lysine. Circular dichroism measurements show that polyglutamine stretches of length 9 or 17 adopt a random coil configuration in aqueous solution. We think that in the disease-associated peptides for normal individuals the stretches of ～20 glutamines are in a random coil conformation, whereas in affected individuals the polyglutamine stretch may be in some other conformation. Our method to design soluble monomeric peptides containing extended polyglutamine stretches may be generally useful in studying other highly aggregating peptides.     

Analysis of STR-PCR products with high-resolution denaturing PAGE

The Pharmacia Multiphor II horizontal electrophoresis chamber is a widespread tool for analysis of PCR products in forensic casework. Up to date, however, there is no protocol for successfully running high-resolution denaturing PAGE (poly-acrylamide gel electrophoresis) on a horizontal electrophoresis chamber. We modified the electrophoresis conditions to make this possible.     

中国人群DXS102座位多态性鉴定及其应用

目的探讨中国人群中ＤＸＳ１０２座位的多态分布。方法应用ＰＣＲ扩增片段长度多态性（Ａｍｐ－ＦＬＰ）研究了无亲缘关系的２３４条Ｘ染色体。结果ＤＸＳ１０２座位等位片段有８个，核心单元ＡＣ二核苷酸重复数为１３～２１，频率分布在０．０１３～０．１５６之间，杂合度观察值和无偏估测值分别为０．８７和０．８０，多态信息含量（ＰＩＣ）０．８０，女性基因型数为２２个，男性基因型数为８个，该座位多态分布符合Ｈａｒｄｙ－Ｗｅｉｎｂｅｒｇ平衡定律。ＤＸＳ１０２座位在中国人群和欧洲人群的分布有明显的种族差异，在中国人群中发现了两个新的等位片段。应用ＤＸＳ１０２座位的短串联重复序列多态性对一接受基因治疗的血友病Ｂ家系进行分析和携带者筛查。结论ＤＸＳ１０２座位连锁分析有望成为一种有效的血友病Ｂ基因诊断的方法。