一成骨不全家系的COL1A1基因突变检测

成骨不全(Osteogenesisimperfecta,OI)是一种由于Ⅰ型胶原形成障碍,导致骨脆性增强为主要症状的 常染色体显性遗传性疾病。临床上主要表现为骨质脆弱、蓝巩膜、耳聋和中等程度的关节畸形等症状。成骨不全 基因分别定位于17q21.31 q22和7q22.1,其致病基因分别为COL1A1和COL1A2。对一常染色体显性遗传的 成骨不全家系进行连锁分析,在COL1A1遗传位点发现紧密连锁(LOD=9.31;θ=.00)。突变检测发现在 COL1A1基因第26内含子5′端剪接位点处存在一由GT转换为AT的致病突变,该突变引起的异常剪接是导致成 骨不全的致病原因之一。     

卵巢早衰候选基因的突变研究进展

卵巢早衰病因复杂, 多数病例病因不明。在已知的病因中, 遗传因素非常重要。卵巢早衰不但可导致不孕症, 患者的低雌激素水平还增加了患骨质疏松症和冠心病的危险。目前临床上的主要治疗措施包括激素替代治疗和供卵治疗不孕症等, 但效果都不理想。鉴定卵巢早衰的致病基因是从根本上治疗和预防该病的基础。目前已发现在X染色体上和常染色体上多个基因与之相关, 文章综述了近年来对卵巢早衰候选基因的突变分析情况, 旨在从分子水平分析研究卵巢早衰的发病机制提供基础。     

鼻咽癌、胃癌中抑癌基因ING1的突变检测

为探讨抑癌基因ING1是否在鼻咽癌和胃癌中存在基因突变,以确定该基因在鼻咽癌、胃癌发病过程中所起的作用,本研究运用PCR－SSCP法分别对鼻咽癌和胃癌组织ING1点突变情况进行检测;对30例鼻咽癌组织和26例胃癌组织的ING1外显子1b扩增的PCR产物进行SSCP分析,结果未发现所扩增的片段有泳运速率的改变,以上结果可以初步排除ING1在鼻咽癌和胃癌中以基因突变方式失活的可能。     

Smith—Fineman—Myers综合征与GRIA3基因的连锁和突变分析

探讨GRIA3基因与中国山东Smith-Fineman-Myers综合征的连锁关系,并分析SFMS患者GRIA3基因突变。采用PCR结合变性聚丙烯酰胺凝胶电泳方法,分析GRIA3基因内多态位点与致病基因之间的连锁关系。采用PCR扩增结合PCR产物直接测序方法检测GRIA3基因开放性阅读框架区域基因突变。GRIA3基因内多态位点分析表明,GRIA3基因与中国山东SFMS家系致病基因紧密连锁,但在该基因开放性阅读框架区域内并未检测到导致疾病的基因突变。中国山东SFMS家系患者不是由于GRIA3基因编码区域基因突变所致。     

一中国脑海绵状血管瘤家系中发现krit1基因新的缺失突变

脑海绵状血管瘤（CCM）是多定位于中枢神经系统的一种脑部血管异常,少数在皮肤和视网膜处有并发症。依据致病基因在染色体上的不同位置分为CCM1、CCM2和CCM33种类型。目前,CCM1、CCM2和CCM3的致病基因已经被克隆,分别为krit1、MGC4607和细胞程序性死亡10基因（PDCD10）。利用连锁分析发现内蒙古的一个家系属于CCM1,突变检测发现患者CCM1基因（krit1）第9内含子和第10外显子拼接位点处存在一“GTA”缺失,该突变导致终止密码子提前出现,产生截短蛋白。实验结果支持krit1为CCM1致病基因。     

Five Candidate Genes for Hamster Cardiomyopathy Did not Map to the Cardiomyopathy Locus by FISH Analysis

The Syrian cardiomyopathic hamster (BIO14.6), that developsboth muscular dystrophy and progressive cardiomyopathy, is widelyused as an animal model of autosomal recessive cardiomyopathymimicking human hypertrophic cardiomyopathy, and five geneshave been proposed as strong candidates for the cause of cardiomyopathy.We recently mapped the cardiomyopathy locus of the hamster tothe centromeric region of chromosome 9qa2.1-b1 by constructionof a genetic linkage map of the Syrian hamster. Thus, we analyzedthe loci of the five candidate genes, tropomyosin, cardiactroponin T, adhalin, calpain 3 and cardiac myosin binding protein-C,by the FISH method, and found that these genes were mapped onthe distal portion of chromosome 12qa5 and 4pa2 and the proximalportion of chromosomes 9qb7, 1qc1.1 and 1qb3, respectively.These results provide strong evidence that the five candidategenes previously proposed are not related to the hamster cardiomyopathy.     

A Novel Deletion Mutation in CCM1 Gene (krit1) is Detected in a Chinese Family with Cerebral Cavernous Malformations

Cerebral Cavernous Malformations (CCM) are vascular malformations that are mostly located in the central nervous system (CNS) and occasionally within the skin and retina, which are classified into three types (CCM1, CCM2 and CCM3) by being located at different loci on chromosomes. At present, CCM1 (7q21), CCM2 (7p13-p15) and CCM3 (3q25.2-q27) are respectively linked to krit1 (Krev interaction trapped gene 1), MGC4607 and PDCD10 (programmed cell death 10). In this work, we identified a novel “GTA” deletion mutation at the acceptor splicing site of intron9/exon 10 on krit1. The mutation results in an abnormally spliced protein by creating a premature termination code at the 23rd amino acid downstream from the sequence alteration. Our results are consistent with previous research on krit1 mutations and confirm the conclusion that KR1T1 haploinsufficiency may be the underlying mechanism of CCM1.     

家族性不宁腿综合征候选基因的连锁分析

不宁腿综合征（restless legs syndrome,RLS)是以下肢部出现蚁行样及酸、麻、胀等不适感而使肢体不得休息为特征的一组病症。由于症状常在晚间发作并导致运动不安,患者长期入睡困难,经受严重的继发性失眠。作为一种常见的神经系统疾病,RLS发病率高达5％,其中原发性RLS多呈阳性家族史,表现为单基因决定的常染色体显性遗传。现在,人们普遍认为RLS的发生很可能与神经系统内多巴胺能功能异常和脑内铁缺乏有关,并初步建立了脑铁－多巴胺能系统的致病模型。为了探求脑铁－多巴胺能系统在RLS中的作用,选择了与脑铁－多巴胺能系统相关的16个疾病侯选基因,在每个候选基因附近染色体区域内选取若干个微卫星多态标记,应用微卫星引物荧光标记－基因扫描技术,对一个汉族家族性不宁腿综合征家系进行了基因分型和常染色体显性遗传模式下的连锁分析,试图从分子遗传学层面上确认或排除一些可能与RLS相关的重要侯选基因。结果显示,当重组系数θ=0.00时,LOD值均小于－2.00,所选位点与家族性不宁腿综合征不连锁。由此得出结论,在本家系中,所有候选基因均与家族性不宁腿综合征的发病无关,家族性不宁腿综合征可能是由其他多巴胺传导和脑铁代谢相关基因所致,或是存在全新的致病机制参与RLS的发生。     

高灵敏度电化学发光PCR方法检测基因点突变研究

近年来发展了一种用于定量检测基因点突变的电化学发光PCR方法。该法采用三联吡啶钌标记的上游引物和生物素标记的下游引物对待测基因进行PCR扩增;随后,采用特定的限制性内切酶对扩增产物进行酶切,由于野生型样品和突变型样品间存在酶切位点的变化,其中只有一种基因型样品能被切断;通过生物素与链霉亲和素包被的磁珠连接,将生物素标记的DNA片段收集到样品池中;进行电化学发光检测,通过所得信号的有无可以判断其基因型。我们分别将该法用于Presenilin-1基因和H-ras癌基因的点突变检测,结果均可明显区分突变型样品和野生型样品。该法具有灵敏、快速、简便、安全等优点,是一种实用的基因点突变检测方法。     

Association Tests for a Censored Quantitative Trait and Candidate Genes in Structured Populations with Multilevel Genetic Relatedness

Summary Several statistical methods for detecting associations between quantitative traits and candidate genes in structured populations have been developed for fully observed phenotypes. However, many experiments are concerned with failure‐time phenotypes, which are usually subject to censoring. In this article, we propose statistical methods for detecting associations between a censored quantitative trait and candidate genes in structured populations with complex multiple levels of genetic relatedness among sampled individuals. The proposed methods correct for continuous population stratification using both population structure variables as covariates and the frailty terms attributable to kinship. The relationship between the time‐at‐onset data and genotypic scores at a candidate marker is modeled via a parametric Weibull frailty accelerated failure time (AFT) model as well as a semiparametric frailty AFT model, where the baseline survival function is flexibly modeled as a mixture of Polya trees centered around a family of Weibull distributions. For both parametric and semiparametric models, the frailties are modeled via an intrinsic Gaussian conditional autoregressive prior distribution with the kinship matrix being the adjacency matrix connecting subjects. Simulation studies and applications to the Arabidopsis thaliana line flowering time data sets demonstrated the advantage of the new proposals over existing approaches.