Showing papers by "Simon G. Gregory published in 2008"

1p36 is a preferential target of chromosome 1 deletions in astrocytic tumours and homozygously deleted in a subset of glioblastomas

Abstract: Astrocytic, oligodendroglial and mixed gliomas are the commonest gliomas in adults. They have distinct phenotypes and clinical courses, but as they exist as a continuous histological spectrum, differentiating them can be difficult. Co-deletions of total 1p and 19q are found in the majority of oligodendrogliomas and considered as a diagnostic marker and a prognostic indicator. The 1p status of astrocytomas has not yet been thoroughly examined. Using a chromosome 1 tile path array, we investigated 108 adult astrocytic tumours for copy number alterations. Total 1p deletions were rare (2%), however partial deletions involving 1p36 were frequently identified in anaplastic astrocytomas (22%) and glioblastomas (34%). Multivariate analysis showed that patients with total 1p deletions had significantly longer survival (P=0.005). In nine glioblastomas homozygous deletions at 1p36 were identified. No somatic mutations were found among the five genes located in the homozygously deleted region. However, the CpG island of TNFRSF9 was hypermethylated in 19% of astrocytic tumours and 87% of glioma cell lines. TNFRSF9 expression was upregulated after demethylation of glioma cell lines. Akt3 amplifications were found in four glioblastomas. Our results indicate that 1p deletions are common anaplastic astrocytomas and glioblastomas but are distinct from the 1p abnormalities in oligodendrogliomas.

Further evidence for a maternal genetic effect and a sex-influenced effect contributing to risk for human neural tube defects.

Abstract: Background Neural tube defects (NTDs), including spina bifida and anencephaly, are the second most common birth defect with an incidence of 1/1000. Genetic factors are believed to contribute to NTD risk and family-based studies can be useful for identifying such risk factors. Methods We ascertained 1066 NTD families (1467 affected patients), including 307 multiplex NTD families. We performed pedigree analysis to describe the inheritance patterns, pregnancy outcomes, and recurrence risks to relatives of various types. Results Myelomeningocele or spina bifida (66.9%) and cranial defects (17.7%) were the most common NTD subtypes observed. The overall male:female ratio for affected individuals was 0.82, and there were even fewer males among individuals with an upper level NTD (0.62). Among twins, 2 of the 5 monozygotic twins and only 3 of 35 dizygotic twins were concordant, while 27% of the same sex twins were concordant, but none of the different sex twins. The estimated 6.3% recurrence risk to siblings (CI 0.04-0.08) is consistent with previous reports. Families with two or more affected individuals show a higher proportion of female transmitters (p = 0.0002). Additionally, the number of affected relatives in maternal compared to paternal lineages was more than double (p = 0.006). There were significantly more miscarriages, infant deaths, and stillborn pregnancies of the maternal aunts and uncles (p Conclusions Our data provide several lines of evidence consistent with a maternal effect, as well as a sex-influenced effect, in the etiology of NTDs.

Comprehensive genetic analysis of the platelet activating factor acetylhydrolase (PLA2G7) gene and cardiovascular disease in case–control and family datasets

Abstract: Platelet-activating factor acetylhydrolase (PLA2G7) is a potent pro- and anti-inflammatory molecule that has been implicated in multiple inflammatory disease processes, including cardiovascular disease. The goal of this study was to investigate the genetic effects of PLA2G7 on coronary artery disease (CAD) risk in two large, independent datasets with CAD. Using a haplotype tagging (ht) approach, 19 ht single nucleotide polymorphisms (SNPs) were genotyped in CATHGEN case-control samples (cases = 806 and controls = 267) and in the GENECARD Family Study (n = 1101 families, 2954 individuals). Single SNP analysis using logistic regression revealed nine SNPs with significant association in all CATHGEN subjects (P = 0.0004-0.02). CATHGEN cases were further stratified into subgroups based on age of CAD onset (AOO) and severity of disease; 599 young affecteds (YA, AOO 56). Significant genetic effects were observed in both OA and YA (P = 0.0001-0.02). The GENECARD probands demonstrated results similar to those seen in the YA CATHGEN cases (P = 0.002-0.05). Of the 19 SNPs genotyped, 3 SNPs result in non-synonymous coding changes (I198T, A379V and R92H). Two of the coding SNPs, R92H and A379V, constitute two of the most significantly associated SNPs, even after Bonferroni correction and appear to represent independent associations (r 2 = 0.09). Multiple additional polymorphisms in low linkage disequilibrium with these coding SNPs were also strongly associated. In summary, PLA2G7 represents an important, potentially functional candidate in the pathophysiology of CAD based on replicated associations using two independent datasets and multiple statistical approaches. Further functional studies involving a combination of risk alleles are warranted.

Genetic and functional association of FAM5C with myocardial infarction

Abstract: We previously identified a 40 Mb region of linkage on chromosome 1q in our early onset coronary artery disease (CAD) genome-wide linkage scan (GENECARD) with modest evidence for linkage (n = 420, LOD 0.95). When the data are stratified by acute coronary syndrome (ACS), this modest maximum in the overall group became a well-defined LOD peak (maximum LOD of 2.17, D1S1589/D1S518). This peak overlaps a recently identified inflammatory biomarker (MCP-1) linkage region from the Framingham Heart Study (maximum LOD of 4.27, D1S1589) and a region of linkage to metabolic syndrome from the IRAS study (maximum LOD of 2.59, D1S1589/D1S518). The overlap of genetic screens in independent data sets provides evidence for the existence of a gene or genes for CAD in this region. A peak-wide association screen (457 SNPs) was conducted of a region 1 LOD score down from the peak marker (168–198 Mb) in a linkage peak for acute coronary syndrome (ACS) on chromosome 1, within a family-based early onset coronary artery disease (CAD) sample (GENECARD). Polymorphisms were identified within the 'family with sequence similarity 5, member C' gene (FAM5C) that show genetic linkage to and are associated with myocardial infarction (MI) in GENECARD. The association was confirmed in an independent CAD case-control sample (CATHGEN) and strong association with MI was identified with single nucleotide polymorphisms (SNPs) in the 3' end of FAM5C. FAM5C genotypes were also correlated with expression of the gene in human aorta. Expression levels of FAM5C decreased with increasing passage of proliferating aortic smooth muscle cells (SMC) suggesting a role for this molecule in smooth muscle cell proliferation and senescence. These data implicate FAM5C alleles in the risk of myocardial infarction and suggest further functional studies of FAM5C are required to identify the gene's contribution to atherosclerosis.

Polymorphisms of the tumor suppressor gene LSAMP are associated with left main coronary artery disease.

Abstract: Previous association mapping on chromosome 3q13-21 detected evidence for association at the limbic system-associated membrane protein (LSAMP) gene in individuals with late-onset coronary artery disease (CAD). LSAMP has never been implicated in the pathogenesis of CAD. We sought to thoroughly characterize the association and the gene. Non-redundant single nucleotide polymorphisms (SNPs) across the gene were examined in an initial dataset (168 cases with late-onset CAD, 149 controls). Stratification analysis on left main CAD (N = 102) revealed stronger association, which was further validated in a validation dataset (141 cases with left main CAD, 215 controls), a third control dataset (N = 255), and a family-based dataset (N = 2954). A haplotype residing in a novel alternative transcript of the LSAMP gene was significant in all independent case-control datasets (p = 0.0001 to 0.0205) and highly significant in the joint analysis (p = 0.00004). Lower expression of the novel alternative transcript was associated with the risk haplotype (p = 0.0002) and atherosclerosis burden in human aortas (p = 0.0001). Furthermore, silencing LSAMP expression in human aortic smooth muscle cells (SMCs) substantially augmented SMC proliferation (p<0.01). Therefore, the risk conferred by the LSAMP haplotype appears to be mediated by LSAMP down-regulation, which may promote SMC proliferation in the arterial wall and progression of atherosclerosis.

A gene expression signature of confinement in peripheral blood of red wolves (Canis rufus).

Abstract: The stresses that animals experience as a result of modification of their ecological circumstances induce physiological changes that leave a signature in profiles of gene expression. We illustrate this concept in a comparison of free range and confined North American red wolves (Canis rufus). Transcription profiling of peripheral blood samples from 13 red wolf individuals in the Alligator River region of North Carolina revealed a strong signal of differentiation. Four hundred eighty-two out of 2980 transcripts detected on Illumina HumanRef8 oligonucleotide bead arrays were found to differentiate free range and confined wolves at a false discovery rate of 12.8% and P < 0.05. Over-representation of genes in focal adhesion, insulin signalling, proteasomal, and tryptophan metabolism pathways suggests the activation of pro-inflammatory and stress responses in confined animals. Consequently, characterization of differential transcript abundance in an accessible tissue such as peripheral blood identifies biomarkers that could be useful in animal management practices and for evaluating the impact of habitat changes on population health, particularly as attention turns to the impact of climate change on physiology and in turn species distributions.

Refinement of 2q and 7p loci in a large multiplex NTD family.

Abstract: BACKGROUND: NTDs are considered complex disorders that arise from an interaction between genetic and environmental factors. NTD family 8776 is a large multigenerational Caucasian family that provides a unique resource for the genetic analysis of NTDs. Previous linkage analysis using a genome-wide SNP screen in family 8776 with multipoint nonparametric mapping methods identified maximum LOD* scores of ∼3.0 mapping to 2q33.1–q35 and 7p21.1–pter. METHODS: We ascertained an additional nuclear branch of 8776 and conducted additional linkage analysis, fine mapping, and haplotyping. Expression data from lymphoblast cell lines were used to prioritize candidate genes within the minimum candidate intervals. Genomic copy number changes were evaluated using BAC tiling arrays and subtelomeric fluorescent in situ hybridization probes. RESULTS: Increased evidence for linkage was observed with LOD* scores of ∼3.3 for both regions. Haplotype analyses narrowed the minimum candidate intervals to a 20.3 Mb region in 2q33.1–q35 between markers rs1050347 and D2S434, and an 8.3 Mb region in 7p21.1–21.3 between a novel marker 7M0547 and rs28177. Within these candidate regions, 16 genes were screened for mutations; however, no obvious causative NTD mutation was identified. Evaluation of chromosomal aberrations using comparative genomic hybridization arrays, subtelomeric fluorescent in situ hybridization, and copy number variant detection techniques within the 2q and 7p regions did not detect any chromosomal abnormalities. CONCLUSIONS: This large NTD family has identified two genomic regions that may harbor NTD susceptibility genes. Ascertainment of another branch of family 8776 and additional fine mapping permitted a 9.1 Mb reduction of the NTD candidate interval on chromosome 7 and 37.3 Mb on chromosome 2 from previously published data. Identification of one or more NTD susceptibility genes in this family could provide insight into genes that may affect other NTD families. Birth Defects Research (Part A), 2008. © 2008 Wiley-Liss, Inc.