强迫谱系障碍与第Ⅱ组代谢型谷氨酸受体相关候选基因位点的连锁分析

目的 了解代谢型谷氨酸受体mGlu2受体（mGluR2）基因、mGlu3受体（mGluR3）基因等与强迫谱系障碍（OCSDs）的连锁关系。方法 选取一个连续三代发病的强迫谱系障碍家系，采集到该家系中12个正常个体，8个受累个体的血样，选取mGluR2、mGluR3基因附近7对微卫星标记引物，采用两点和多点非参数分析的方法对该家系进行连锁分析。结果 7对微卫星标记位点的两点和多点非参数分析LOD值（NPL值），位于mGluR3基因附近的标记D7S644两点非参数分析NPL值为1．719（P=0．078），多点非参数分析NPL值为1．712（P=0．078），达到验证性连锁的阈值（NPL=1．2），但未达到提示性连锁的阕值（NPL=2．2），D7S2481两点非参数分析NPL值为0．628（P=0．179），多点非参数分析NPL值为0．852（P=0．141），接近验证性连锁的阈值，其余5对微卫星标记位点非参数分析NPL值均未达到验证性连锁的阈值。结论 提示mGluR3基因与OCSDs可能存在连锁关系，不能排除mGluR2基因与OCSDs的相关性。     

Linkage studies of psychiatric disorders

Summary Linkage analysis has been successful in identifying the genetic basis of numerous Mendelian diseases. These successes were due in part to the rapid developments in molecular biology, which have yielded a plethora of informative genetic markers. Although there is strong evidence that the manifestation of schizophrenia and bipolar affective disorders is controlled by genes, no evidence for linkage has been established. For psychiatric disorders, the most important limiting factor is likely to be the lack of single loci with very large effects that occur with any relevant frequency. The difficulties of linkage studies in psychiatric disorders are discussed with reference to non-psychiatric genetic diseases for which linkage to genetic markers has been successful. Recommendations for collecting information to clarify the patterns of transmission of the psychiatric disorders are described.     

Complex Genetic Disease: Can Genetic Strategies in Alzheimer's Disease and New Genetic Mechanisms Be Applied to Epilepsy?

Summary: Strategies used in molecular genetics have changed modern neurology. The gene or genes responsible for several major neurologic diseases have now been identified using "reverse" or positional genetics. Unexpected new genetic mechanisms have been discovered in human neurologic diseases, including (a) identical mutations of the prion protein gene in Creutzfeldt-Jakob disease and fatal familial insomnia with the phenotypic expression directed by an accompanying polymorphism; (b) stable duplications of chromosome 17 in Charcot-Marie-Tooth disease (type 1 A) that involve many genes, only one of which appears to cause neuropathy; and (c) highly variable, dynamic mutations in myotonic dystrophy, fragile X syndrome, and Kennedy's syndrome that modulate variable expressivity in multiple tissues. There is growing recognition that neurologic diseases are often complex genetic diseases with multifactorial rather than simple modes of inheritance. For example, genetic association/linkage strategies have interacted with biochemistry and immunopathology studies to produce new insights into the disease mechanism of late-onset Alzheimer's disease. The role of apolipoprotein E in late-onset Alzheimer's disease is an example of how new analytical techniques of genetic disease can be applied to dissect multiple genes. Similar research strategies are suggested for the study of epilepsy as a complex disease.     

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.     

Non-linkage of the islet amyloid polypeptide gene with Type 2 (non-insulin-dependent) diabetes mellitus

Summary Type 2 (non-insulin-dependent) diabetes is associated with the deposition of islet amyloid. The major formative peptide, islet amyloid polypeptide, has recently been characterised and an abnormality of the structure or expression of this gene is a possible candidate for the inherited component of Type 2 diabetes. A restriction fragment length polymorphism of the gene has been identified with Pvu II. To study the relationship between the islet amyloid polypeptide gene and Type 2 diabetes, two distinct genetic approaches have been undertaken. Firstly, non-linkage has been demonstrated in four pedigrees, with four normoglycaemic first degree relatives having an allele associated with diabetes in other family members, and one affected relative not having the putatively associated allele. The LOD score taking age-related penetrance into account was –1.68, making linkage unlikely (p=0.02). Secondly, in a population-based restriction fragment length polymorphism survey, no linkage disequilibrium of the alleles was found between a population of unrelated Caucasian subjects with Type 2 diabetes and a normal population. A mutation in or near the islet amyloid polypeptide gene is thus unlikely to be a common cause of Type 2 diabetes.     

Identification of the phenotype in psychiatric genetics

Summary Statistical procedures and molecular genetic techniques have attained a fine degree of resolution. Their ability to find disease genes has revolutionized medicine and raised hopes for breakthroughs in psychiatry. However, such breakthroughs may require an equally discriminating nosology. A psychiatric genetic nosology seeks to classify patients into categories that correspond to distinct genetic entities by addressing the problem of diagnostic accuracy: the degree to which a diagnosis correctly classifies people with and without a putative genetic illness. We review methods that deal with misclassification in genetic studies. These are clinical and epidemiological approaches that deal directly with how to define the observable manifestation of a putative genotype. We discuss two groups of methods: those that use known phenotypes and those that design new phenotypes.     

红色素基因RFLP及其与情感性精神病关系的研究

以红色素基因全长ｃＤＮＡ作探针，２０例正常人，２６例双相型情感性精神病患者进行ＲＦＬＰ分析。ＳａｃＩ酶切显示：部分正常人和部分患者基因组ＤＮＡ产生的７．５ｋｂ，４．８ｋｂ，４．５ｋｂ呈多态性改变的片段。正常人具多态改变的占４５％，患者为４６．２％，按Ｘ染色体数计，正常人出现７．５ｋｂ限制性片段的频率为１４．３％，患者为３２．４％，但两者差异不显著。     

Ankylosing spondylitis susceptibility loci defined by genome-search meta-analysis

In genome scans of ankylosing spondylitis (AS), with the exception of the HLA loci, linkage has not been easy to replicate across studies. We applied the genome-search meta-analysis (GSMA) method to genome scans of AS and spondyloarthropathy (SpA) to assess evidence for linkage across studies. Three AS genome scans and one SpA scan including 430 families with 1,048 affected individuals were used. All four original genome scans mainly analyzed Caucasian families. Seven bins had both Psumrnk and Pord<0.05, suggesting these bins most likely contain AS-linked loci; bin 6.2, 6.1, 6.3, 16.3, 19.2, 17.1, and 16.4. The GSMA produced significant genome-wide evidence for linkage on chromosome 6p22.3–6p21.1 (Psumrnk=0.000003), including the HLA locus. In addition to the HLA-B27 locus, strong linkage evidence was found on chromosome 6p25.3–6p22.3 (Psumrnk=0.0013) and 6p21.1–6p15 (Psumrnk=0.043). In the GSMA of four genome scans including one SpA study, the bin 9.4 (9q21.32–9q33.1) was newly found for linkage (Psumrnk=0.043, Pord=0.013). This GSMA added the evidence of the HLA loci as the greatest susceptibility factor to AS and showed evidences of chromosome 6, 16q, 19, 17p, and 9q as non-HLA susceptibility loci.     

Analysis of the MTHFR 1298A-->C and 677C-->T polymorphisms as risk factors for neural tube defects

The thermolabile variant (677TT) of methylenetetrahydrofolate reductase (MTHFR) is a known risk factor for neural tube defects (NTDs). The relationship between a second MTHFR polymorphism (1298A→C) and NTD risk has been inconsistent between studies. We genotyped 276 complete NTD triads (mother, father and child affected with an NTD) and 256 controls for MTHFR 1298A→C. Our findings do not support a role for the 1298A→C polymorphism in NTDs (OR 0.85 (95% CI 0.49–1.47), p= 0.55), nor do we observe a combined effect with the 677C→T polymorphism. Electronic Publication     

Chromatin interactions in differentiating keratinocytes reveal novel atopic dermatitis– and psoriasis-associated genes

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