Replication of ZNF804A gene variant associations with risk of heroin addiction.

Heroin addiction is heritable, but few specific genetic variants have been reproducibly associated with this disease. The zinc finger protein 804A (ZNF804A) gene is a biologically plausible susceptibility gene for heroin addiction, given its function as a transcription factor in human brain. Novel associations of two common ZNF804A single nucleotide polymorphisms (SNPs), rs7597593 and rs1344706, with heroin addiction have been reported in Han Chinese. Both SNPs have also been implicated for regulating ZNF804A expression in human brain, including the addiction-relevant dorsolateral prefrontal cortex. In this independent replication study, we tested the rs7597593 and rs1344706 SNP genotypes and their corresponding haplotypes for association with heroin addiction using cases drawn from the Urban Health Study and population controls: total N = 10 757 [7095 European Americans (EAs) and 3662 African Americans (AAs)]. We independently replicated both ZNF804A SNP associations in EAs: the rs7597593-T (P = 0.016) and rs1344706-A (P = 0.029) alleles both being associated with increased risk of heroin addiction, consistent with the prior report. Neither SNP was associated in AAs alone, but meta-analysis across both ancestry groups resulted in significant associations for rs1344706-A [P = 0.016, odds ratio (95% confidence interval) = 1.13 (1.02-1.25)] and its haplotype with rs7597593-T [P = 0.0067, odds ratio (95% confidence interval) = 1.16 (1.04-1.29)]. By showing consistent associations across independent studies and diverse ancestry groups, our study provides evidence that these two ZNF804A SNPs and their risk haplotype are among the few replicable genetic associations with heroin addiction.

Dynamics of global transcriptome in bovine matured oocytes and preimplantation embryos.

Global activation of the embryonic genome is the most critical event in early mammalian development. After fertilization, a rich supply of maternal proteins and RNAs support development whereas a number of zygotic and embryonic genes are expressed in a stage-specific manner leading to embryonic genome activation (EGA). However, the identities of embryonic genes expressed and the mechanism(s) of EGA are poorly defined in the bovine. Using the Affymetrix bovine-specific DNA microarray as the biggest available array at present, we analyzed gene expression at two key stages of bovine development, matured oocytes (MII) and 8-cell-stage embryos, constituting the ultimate reservoir for life and a stage during which EGA takes place, respectively. Key genes in regulation of transcription, chromatin-structure cell adhesion, and signal transduction were up-regulated at the 8-cell stage as compared with 8-cell embryos treated with alpha-amanitin and MII. Genes controlling DNA methylation and metabolism were up-regulated in MII. These changes in gene expression, related to transcriptional machinery, chromatin structure, and the other cellular functions occurring during several cleavage stages, are expected to result in a unique chromatin structure capable of maintaining totipotency during embryogenesis and leading to differentiation during postimplantation development. Dramatic reprogramming of gene expression at the onset of development also has implications for cell plasticity in somatic cell nuclear transfer, genomic imprinting, and cancer.

Microarray profiling of isolated abdominal subcutaneous adipocytes from obese vs non-obese Pima Indians: increased expression of inflammation-related genes.

AIMS/HYPOTHESIS: Obesity increases the risk of developing major diseases such as diabetes and cardiovascular disease. Adipose tissue, particularly adipocytes, may play a major role in the development of obesity and its comorbidities. The aim of this study was to characterise, in adipocytes from obese people, the most differentially expressed genes that might be relevant to the development of obesity. METHODS: We carried out microarray gene profiling of isolated abdominal subcutaneous adipocytes from 20 non-obese (BMI 25+/-3 kg/m2) and 19 obese (BMI 55+/-8 kg/m2) non-diabetic Pima Indians using Affymetrix HG-U95 GeneChip arrays. After data analyses, we measured the transcript levels of selected genes based on their biological functions and chromosomal positions using quantitative real-time PCR. RESULTS: The most differentially expressed genes in adipocytes of obese individuals consisted of 433 upregulated and 244 downregulated genes. Of these, 410 genes could be classified into 20 functional Gene Ontology categories. The analyses indicated that the inflammation/immune response category was over-represented, and that most inflammation-related genes were upregulated in adipocytes of obese subjects. Quantitative real-time PCR confirmed the transcriptional upregulation of representative inflammation-related genes (CCL2 and CCL3) encoding the chemokines monocyte chemoattractant protein-1 and macrophage inflammatory protein 1alpha. The differential expression levels of eight positional candidate genes, including inflammation-related THY1 and C1QTNF5, were also confirmed. These genes are located on chromosome 11q22-q24, a region with linkage to obesity in the Pima Indians. CONCLUSIONS/INTERPRETATION: This study provides evidence supporting the active role of mature adipocytes in obesity-related inflammation. It also provides potential candidate genes for susceptibility to obesity.

A chromosome 14 risk locus for simple phobia: results from a genomewide linkage scan.

We conducted a 10 centimorgan (cM) linkage genome scan in a set of American extended pedigrees ascertained through probands with panic disorder. Several anxiety disorders segregate in these families. In this article, we describe results for simple phobia from 14 of these families (including 129 subjects of whom 57 are affected). A total of 422 markers were genotyped. Multipoint lod score analyses (fully parametric and simple parametric models) and nonparametric analyses were completed using ALLEGRO. We observed significant linkage of simple phobia to chromosome 14 markers. The highest lod score under a fully parametric model was 3.17, at marker D14S75, under a dominant model. Under a fully parametric recessive model, the maximum lod score, also at D14S75, was 2.86. Analysis under a simple parametric model resulted in lod scores of 3.70 (dominant model) or 3.30 (recessive model). The highest Zlr score observed was 3.93 (P = 4.1 x 10(-5)). The Zlr score was >1 for an extensive region, >77 cM. In all, 12 of the 14 families studied provided positive or zero lod scores at marker D14S75 (dominant model). The homologous genomic region has been implicated by studies mapping quantitative trait loci for a mouse model of fear. The linkage peak may be regarded as highly promising, owing to the breadth of the peak, the convergence of results under different models of inheritance and different analysis methods, and the support from an animal model. This is the first genome scan linkage study for simple phobia, a common disorder that causes high morbidity in the US population.

Evidence for linkage and association with reading disability on 6p21.3-22.

Reading disability (RD), or dyslexia, is a common heterogeneous syndrome with a large genetic component. Several studies have consistently found evidence for a quantitative-trait locus (QTL) within the 17 Mb (14.9 cM) that span D6S109 and D6S291 on chromosome 6p21.3-22. To characterize further linkage to the QTL, to define more accurately the location and the effect size, and to identify a peak of association, we performed Haseman-Elston and DeFries-Fulker linkage analyses, as well as transmission/disequilibrium, total-association, and variance-components analyses, on 11 quantitative reading and language phenotypes. One hundred four families with RD were genotyped with a new panel of 29 markers that spans 9 Mb of this region. Linkage results varied widely in degree of statistical significance for the different linkage tests, but multipoint analysis suggested a peak near D6S461. The average 6p QTL heritability for the 11 reading and language phenotypes was 0.27, with a maximum of 0.66 for orthographic choice. Consistent with the region of linkage described by these studies and others, there was a peak of transmission disequilibrium with a QTL centered at JA04 (chi2=9.48; empirical P=.0033; orthographic choice), and there was strong evidence for total association at this same marker (chi2=11.49; P=.0007; orthographic choice). Although the boundaries of the peak could not be precisely defined, the most likely location of the QTL is within a 4-Mb region surrounding JA04.

A role for the Agouti-Related Protein promoter in obesity and type 2 diabetes.

The murine Agouti-Related Protein (mAGRP) is upregulated in obese and diabetic mice and can stimulate hyperphagia when overexpressed in transgenic models. Here we report upstream nucleotide sequences of the human hAGRP gene with putative recognition sites for transcription factors including a site for the STAT transactivators. A polymorphism (-38C-->T) was identified in the promoter region and the C/C genotype had significantly higher promoter activity and affinity for transcription factors as tested in periphery- and hypothalamus-derived cell lines. The polymorphic site could affect the expression levels of hAGRP and the high expressing C/C genotype was significantly associated with high BMI and type 2 diabetes in Africans.

Anti-fibrillin-1 autoantibodies in systemic sclerosis are GM and KM allotype-restricted.

GM and KM allotypes--genetic markers of immunoglobulin (Ig) gamma and kappa chains, respectively--have been shown to play an important role in genetic predisposition to some autoimmune diseases. To determine their role in susceptibility to systemic sclerosis (SSc; scleroderma) and in the generation of anti-fibrillin-1 antibodies, 148 SSc patients and 191 controls were typed for several GM and KM allotypes by a standard hemagglutination inhibition method. IgG and IgM antibodies to fibrillin-1 were measured by radioimmunoassay. GM and KM phenotypes were not significantly associated with SSc. However, these determinants significantly influenced the production of anti-fibrillin-1 antibodies in SSc patients. In Caucasians, GM1,3,17 23 5,13,21 and GM3 23 5,13 phenotypes were associated with the presence and absence of IgG autoantibodies, respectively. The production of these autoantibodies was also associated with KM allotypes, KM1,3 heterozygosity being associated with response and homozygosity for the KM3 allele with nonresponse to fibrillin-1. In African-Americans, the KM1 homozygotes were associated with the absence of anti-fibrillin-1 antibodies and the KM3 homozygotes with the presence of autoantibodies. In this ethnic group, the GM1,17 5,13 phenotype was associated with the absence of IgM autoantibodies. This represents the first description of genetic control of autoimmunity to fibrillin-1 in scleroderma.

Comparison of the QTDT analysis for IgE in the CSGA data set.

Over the past few years at least 13 transmission/disequilibrium test (TDT)-based tests have been developed for quantitative (Q) traits for the assessment of association or linkage in the presence of the other. A total of six of these QTDT methods were used to analyze log10IgE in the Collaborative Study on the Genetics of Asthma data set. Only moderate agreement was found between the tests. The results of the QTDT analyses were only slightly affected by the use of gender and age as covariates. Results from analysis of IgE and log10IgE were inconsistent. Our conclusion is that there is only modest agreement among the QTDT methods examined, covariates should be used even if they have a small effect, and that data should be normalized before analysis.

Epidemiology of lung cancer with special reference to genetics, bioassays, women, and developing countries.

The twentieth century may be looked back upon as the century of lung cancer. At the beginning of the century lung cancer was quite rare, but this century the rates have increased approximately 10-fold and it is the second most common type of cancer and has become the leading cause of death due to cancer in the United States. The rate of lung cancer among U.S. women continues to rise, in contrast rates in U.S. men have been declining since about 1990. Cigarette smoking accounts for 85-90% of lung cancer deaths in the United States. However, only 10-15% of smokers eventually develop lung cancer. In the past 25 years, since the U.S. Surgeon General's ground breaking report in 1964, overall smoking rates have been declining, but smoking still remains a significant behavior. More troubling, the rates of smoking continue to increase in many parts of the world. Advances in molecular biology and early diagnosis have increased the understanding of lung cancer etiology and may be effective in uncovering more efficient detection and treatment regimens. These advances will hopefully make lung cancer as uncommon at the end of the twenty-first century, as it was at the beginning of the twentieth century.

Assessing linkage of monoamine oxidase B in a genome-wide scan using a univariate variance components approach.

We report results when one alcoholism related quantitative trait, monoamine oxidase B (MAOB), is analyzed by the variance components approach for linkage [Amos, 1994; Amos et al., 1996] using the Collaborative Study on the Genetics of Alcoholism data set provided for the Genetic Analysis Workshop 11. We used two different covariate models, one with age at interview, sex, ethnicity, and smoking status and the other with age at interview, sex, and ethnicity. The univariate analysis showed 24 markers on four different chromosomes (1, 4, 9, and 12) to have evidence for linkage with the quantitative trait (single-point and multipoint linkage). However, when outliers for MAOB were removed, the significant evidence for linkage disappeared.

Familial analysis of event related potentials.

This report summarizes our analysis of the auditory and visual event related evoked potentials. These data were collected as a component of the Collaborative Study on the Genetics of Alcoholism and distributed as a part of the data available for the Genetic Analysis Workshop 11. For this analysis, we collapsed the data collected from eight leads using principal components methods. Using four collapsed variables derived from the principal components, we used regression analysis to adjust for environmental and demographic variables. We then fit the best fitting regression model and calculated the residuals. Using the residuals, we performed segregation analysis using S.A.G.E. Finally, we applied Markov chain Monte Carlo reverse jump methods to identify areas with potential quantitative trait loci. Our findings indicate that there may be an underlying genetic component to the potentials.

Genome scans for genetic predisposition to alcoholism by use of transmission disequilibrium test analyses.

We report the results of the analysis of three measures of alcoholism and six associated symptoms using transmission disequilibrium (TDT) analysis on data from the Collaborative Study on the Genetics of Alcoholism data set. Implementation of identity-by-state (IBS) routines for error checking revealed 10 reported full siblings that were rejected as a full sibling to all of their purported full siblings with p < 0.05. TDT analysis revealed two loci with significant transmission disequilibrium (p < 0.001) on chromosomes 1 and 7. Analysis by parental origin found alleles at three loci displaying significant disequilibrium in the transmission of the paternal alleles for at least three of the nine tested traits. These loci are on chromosomes 6, 9, and 13. Analyses of Caucasian families alone and the use of a single affected individual from each family also yielded significant results for the loci on chromosomes 6, 9, and 13.

A genome-wide search for susceptibility genes linked to alcohol dependence.

We performed two-point linkage analysis during a genome-wide search for susceptibility genes that predispose to alcohol dependence with the Collaborative Study on the Genetics on Alcoholism (COGA) data made available for the Genetic Analysis Workshop 11 (GAW11). For chromosomes 1 and 4 our findings supported results reported by Reich et al. [1998] based on the same data. We found similarity between our findings in regions on chromosomes 8 and 10 and reported results for schizophrenia linkage studies. Differences between our results with COGA data and those obtained by Reich et al. [1998] are due to our use of a lod score method versus their use of the affected relative pair (sib pair) method.

Comparison of linkage-disequilibrium methods for localization of genes influencing quantitative traits in humans.

Linkage disequilibrium has been used to help in the identification of genes predisposing to certain qualitative diseases. Although several linkage-disequilibrium tests have been developed for localization of genes influencing quantitative traits, these tests have not been thoroughly compared with one another. In this report we compare, under a variety of conditions, several different linkage-disequilibrium tests for identification of loci affecting quantitative traits. These tests use either single individuals or parent-child trios. When we compared tests with equal samples, we found that the truncated measured allele (TMA) test was the most powerful. The trait allele frequencies, the stringency of sample ascertainment, the number of marker alleles, and the linked genetic variance affected the power, but the presence of polygenes did not. When there were more than two trait alleles at a locus in the population, power to detect disequilibrium was greatly diminished. The presence of unlinked disequilibrium (D'*) increased the false-positive error rates of disequilibrium tests involving single individuals but did not affect the error rates of tests using family trios. The increase in error rates was affected by the stringency of selection, the trait allele frequency, and the linked genetic variance but not by polygenic factors. In an equilibrium population, the TMA test is most powerful, but, when adjusted for the presence of admixture, Allison test 3 becomes the most powerful whenever D'*>.15.

The quantitative LOD score: test statistic and sample size for exclusion and linkage of quantitative traits in human sibships.

We present a test statistic, the quantitative LOD (QLOD) score, for the testing of both linkage and exclusion of quantitative-trait loci in randomly selected human sibships. As with the traditional LOD score, the boundary values of 3, for linkage, and -2, for exclusion, can be used for the QLOD score. We investigated the sample sizes required for inferring exclusion and linkage, for various combinations of linked genetic variance, total heritability, recombination distance, and sibship size, using fixed-size sampling. The sample sizes required for both linkage and exclusion were not qualitatively different and depended on the percentage of variance being linked or excluded and on the total genetic variance. Information regarding linkage and exclusion in sibships larger than size 2 increased as approximately all possible pairs n(n-1)/2 up to sibships of size 6. Increasing the recombination (theta) distance between the marker and the trait loci reduced empirically the power for both linkage and exclusion, as a function of approximately (1-2theta)4.

Polymorphic markers in apolipoprotein C-III gene flanking regions and hypertriglyceridemia.

Hypertriglyceridemia and hyperlipidemia are common disorders associated with coronary artery disease and premature death. The proteins encoded by the apolipoprotein (apo) A-I/C-III/A-IV gene cluster are involved in the metabolism of both triglycerides and cholesterol. In a large sample of individuals from the ARIC study, six polymorphic markers were typed and plasma lipid values were measured to determine whether the well-established association between the Sst I S2 allele in the 3'-untranslated region of the apo C-III gene and hypertriglyceridemia was due to disequilibrium with variation in the 5' regulatory region of the apo C-III gene. The Sst I polymorphism was significantly associated with hypertriglyceridemia (P = .006) but not with carotid artery wall thickness, plasma apo C-III levels, or elevated cholesterol. The frequency of the S2 allele was 0.14 in those with high triglyceride levels and 0.05 in those with low triglyceride levels. None of the 5' flanking polymorphisms were significantly associated with any of the plasma lipids studied. There was substantial linkage disequilibrium between the Sst I polymorphism and each of the 5' apo C-III polymorphisms; however, the significant association between the apo C-III haplotypes and hypertriglyceridemia (odds ratio, 4.0; P < .0001) was solely attributable to the effects of the Sst I polymorphism (odds ratio, 3.96). As a part of these analyses, we also defined a unique haplotype that is inversely associated with the occurrence of hypertriglyceridemia, suggesting further molecular analyses of this important gene region.