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86 result(s) for "Williams, L. Keoki"
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Integrative omics of schizophrenia: from genetic determinants to clinical classification and risk prediction
Schizophrenia (SCZ) is a debilitating neuropsychiatric disorder with high heritability and complex inheritance. In the past decade, successful identification of numerous susceptibility loci has provided useful insights into the molecular etiology of SCZ. However, applications of these findings to clinical classification and diagnosis, risk prediction, or intervention for SCZ have been limited, and elucidating the underlying genomic and molecular mechanisms of SCZ is still challenging. More recently, multiple Omics technologies – genomics, transcriptomics, epigenomics, proteomics, metabolomics, connectomics, and gut microbiomics – have all been applied to examine different aspects of SCZ pathogenesis. Integration of multi-Omics data has thus emerged as an approach to provide a more comprehensive view of biological complexity, which is vital to enable translation into assessments and interventions of clinical benefit to individuals with SCZ. In this review, we provide a broad survey of the single-omics studies of SCZ, summarize the advantages and challenges of different Omics technologies, and then focus on studies in which multiple omics data are integrated to unravel the complex pathophysiology of SCZ. We believe that integration of multi-Omics technologies would provide a roadmap to create a more comprehensive picture of interactions involved in the complex pathogenesis of SCZ, constitute a rich resource for elucidating the potential molecular mechanisms of the illness, and eventually improve clinical assessments and interventions of SCZ to address clinical translational questions from bench to bedside.
Substance use disorders and risk of suicide in a general US population: a case control study
Background Prior research suggests that substance use disorders (SUDs) are associated with risk of suicide mortality, but most previous work has been conducted among Veterans Health Administration patients. Few studies have examined the relationship between SUDs and suicide mortality in general populations. Our study estimates the association of SUDs with suicide mortality in a general US population of men and women who receive care across eight integrated health systems. Methods We conducted a case–control study using electronic health records and claims data from eight integrated health systems of the Mental Health Research Network. Participants were 2674 men and women who died by suicide between 2000–2013 and 267,400 matched controls. The main outcome was suicide mortality, assessed using data from the health systems and confirmed by state death data systems. Demographic and diagnostic data on substance use disorders and other health conditions were obtained from each health system. First, we compared descriptive statistics for cases and controls, including age, gender, income, and education. Next, we compared the rate of each substance use disorder category for cases and controls. Finally, we used conditional logistic regression models to estimate unadjusted and adjusted odds of suicide associated with each substance use disorder category. Results All categories of substance use disorders were associated with increased risk of suicide mortality. Adjusted odds ratios ranged from 2.0 (CI 1.7, 2.3) for patients with tobacco use disorder only to 11.2 (CI 8.0, 15.6) for patients with multiple alcohol, drug, and tobacco use disorders. Substance use disorders were associated with increased relative risk of suicide for both women and men across all categories, but the relative risk was more pronounced in women. Conclusions Substance use disorders are associated with significant risk of suicide mortality, especially for women, even after controlling for other important risk factors. Experiencing multiple substance use disorders is particularly risky. These findings suggest increased suicide risk screening and prevention efforts for individuals with substance use disorders are needed.
Variation in the glucose transporter gene SLC2A2 is associated with glycemic response to metformin
Ewan Pearson, Kathleen Giacomini and the Metformin Genetics Consortium perform a genome-wide association study for glycemic response to the antidiabetic drug metformin. They find an intronic allele of the GLUT2 glucose transporter gene that associates with greater metformin action, an effect that is more pronounced in obese individuals. Metformin is the first-line antidiabetic drug with over 100 million users worldwide, yet its mechanism of action remains unclear 1 . Here the Metformin Genetics (MetGen) Consortium reports a three-stage genome-wide association study (GWAS), consisting of 13,123 participants of different ancestries. The C allele of rs8192675 in the intron of SLC2A2 , which encodes the facilitated glucose transporter GLUT2, was associated with a 0.17% ( P = 6.6 × 10 −14 ) greater metformin-induced reduction in hemoglobin A1c (HbA1c) in 10,577 participants of European ancestry. rs8192675 was the top cis expression quantitative trait locus ( cis -eQTL) for SLC2A2 in 1,226 human liver samples, suggesting a key role for hepatic GLUT2 in regulation of metformin action. Among obese individuals, C-allele homozygotes at rs8192675 had a 0.33% (3.6 mmol/mol) greater absolute HbA1c reduction than T-allele homozygotes. This was about half the effect seen with the addition of a DPP-4 inhibitor, and equated to a dose difference of 550 mg of metformin, suggesting rs8192675 as a potential biomarker for stratified medicine.
Whole-Genome Sequencing of Pharmacogenetic Drug Response in Racially Diverse Children with Asthma
Albuterol, a bronchodilator medication, is the first-line therapy for asthma worldwide. There are significant racial/ethnic differences in albuterol drug response. To identify genetic variants important for bronchodilator drug response (BDR) in racially diverse children. We performed the first whole-genome sequencing pharmacogenetics study from 1,441 children with asthma from the tails of the BDR distribution to identify genetic association with BDR. We identified population-specific and shared genetic variants associated with BDR, including genome-wide significant (P < 3.53 × 10 ) and suggestive (P < 7.06 × 10 ) loci near genes previously associated with lung capacity (DNAH5), immunity (NFKB1 and PLCB1), and β-adrenergic signaling (ADAMTS3 and COX18). Functional analyses of the BDR-associated SNP in NFKB1 revealed potential regulatory function in bronchial smooth muscle cells. The SNP is also an expression quantitative trait locus for a neighboring gene, SLC39A8. The lack of other asthma study populations with BDR and whole-genome sequencing data on minority children makes it impossible to perform replication of our rare variant associations. Minority underrepresentation also poses significant challenges to identify age-matched and population-matched cohorts of sufficient sample size for replication of our common variant findings. The lack of minority data, despite a collaboration of eight universities and 13 individual laboratories, highlights the urgent need for a dedicated national effort to prioritize diversity in research. Our study expands the understanding of pharmacogenetic analyses in racially/ethnically diverse populations and advances the foundation for precision medicine in at-risk and understudied minority populations.
Socioeconomic Status and Childhood Asthma in Urban Minority Youths. The GALA II and SAGE II Studies
The burden of asthma is highest among socioeconomically disadvantaged populations; however, its impact is differentially distributed among racial and ethnic groups. To assess the collective effect of maternal educational attainment, annual household income, and insurance type on childhood asthma among minority, urban youth. We included Mexican American (n = 485), other Latino (n = 217), and African American (n = 1,141) children (aged 8-21 yr) with and without asthma from the San Francisco Bay Area. An index was derived from maternal educational attainment, annual household income, and insurance type to assess the collective effect of socioeconomic status on predicting asthma. Logistic regression stratified by racial and ethnic group was used to estimate adjusted odds ratios (aOR) and their 95% confidence intervals (CI). We further examined whether acculturation explained the socioeconomic-asthma association in our Latino population. In the adjusted analyses, African American children had 23% greater odds of asthma with each decrease in the socioeconomic index (aOR, 1.23; 95% CI, 1.09-1.38). Conversely, Mexican American children have 17% reduced odds of asthma with each decrease in the socioeconomic index (aOR, 0.83; 95% CI, 0.72-0.96) and this relationship was not fully explained by acculturation. This association was not observed in the other Latino group. Socioeconomic status plays an important role in predicting asthma, but has different effects depending on race and ethnicity. Further steps are necessary to better understand the risk factors through which socioeconomic status could operate in these populations to prevent asthma.
Asthma and its relationship to mitochondrial copy number: Results from the Asthma Translational Genomics Collaborative (ATGC) of the Trans-Omics for Precision Medicine (TOPMed) program
Mitochondria support critical cellular functions, such as energy production through oxidative phosphorylation, regulation of reactive oxygen species, apoptosis, and calcium homeostasis. Given the heightened level of cellular activity in patients with asthma, we sought to determine whether mitochondrial DNA (mtDNA) copy number measured in peripheral blood differed between individuals with and without asthma. Whole genome sequence data was generated as part of the Trans-Omics for Precision Medicine (TOPMed) Program on participants from the Study of Asthma Phenotypes and Pharmacogenomic Interactions by Race-ethnicity (SAPPHIRE) and the Study of African Americans, Asthma, Genes, & Environment II (SAGE II). We restricted our analysis to individuals who self-identified as African American (3,651 asthma cases and 1,344 controls). Mitochondrial copy number was estimated using the sequencing read depth ratio for the mitochondrial and nuclear genomes. Respiratory complex expression was assessed using RNA-sequencing. Average mitochondrial copy number was significantly higher among individuals with asthma when compared with controls (SAPPHIRE: 218.60 vs. 200.47, P<0.001; SAGE II: 235.99 vs. 223.07, P<0.001). Asthma status was significantly associated with mitochondrial copy number after accounting for potential explanatory variables, such as participant age, sex, leukocyte counts, and mitochondrial haplogroup. Despite the consistent relationship between asthma status and mitochondrial copy number, the latter was not associated with time-to-exacerbation or patient-reported asthma control. Mitochondrial respiratory complex gene expression was disproportionately lower in individuals with asthma when compared with individuals without asthma and other protein-encoding genes. We observed a robust association between asthma and higher mitochondrial copy number. Asthma having an effect on mitochondria function was also supported by lower respiratory complex gene expression in this group.
Identifying Pleiotropic Genes in Genome-Wide Association Studies for Multivariate Phenotypes with Mixed Measurement Scales
We propose a multivariate genome-wide association test for mixed continuous, binary, and ordinal phenotypes. A latent response model is used to estimate the correlation between phenotypes with different measurement scales so that the empirical distribution of the Fisher's combination statistic under the null hypothesis is estimated efficiently. The simulation study shows that our proposed correlation estimation methods have high levels of accuracy. More importantly, our approach conservatively estimates the variance of the test statistic so that the type I error rate is controlled. The simulation also shows that the proposed test maintains the power at the level very close to that of the ideal analysis based on known latent phenotypes while controlling the type I error. In contrast, conventional approaches-dichotomizing all observed phenotypes or treating them as continuous variables-could either reduce the power or employ a linear regression model unfit for the data. Furthermore, the statistical analysis on the database of the Study of Addiction: Genetics and Environment (SAGE) demonstrates that conducting a multivariate test on multiple phenotypes can increase the power of identifying markers that may not be, otherwise, chosen using marginal tests. The proposed method also offers a new approach to analyzing the Fagerström Test for Nicotine Dependence as multivariate phenotypes in genome-wide association studies.
A genome-wide association and admixture mapping study of bronchodilator drug response in African Americans with asthma
Short-acting β2-adrenergic receptor agonists (SABAs) are the most commonly prescribed asthma medications worldwide. Response to SABAs is measured as bronchodilator drug response (BDR), which varies among racial/ethnic groups in the United States. However, the genetic variation that contributes to BDR is largely undefined in African Americans with asthma. To identify genetic variants that may contribute to differences in BDR in African Americans with asthma, we performed a genome-wide association study (GWAS) of BDR in 949 African-American children with asthma, genotyped with the Axiom World Array 4 (Affymetrix, Santa Clara, CA) followed by imputation using 1000 Genomes phase III genotypes. We used linear regression models adjusting for age, sex, body mass index (BMI) and genetic ancestry to test for an association between BDR and genotype at single-nucleotide polymorphisms (SNPs). To increase power and distinguish between shared vs. population-specific associations with BDR in children with asthma, we performed a meta-analysis across 949 African Americans and 1830 Latinos (total = 2779). Finally, we performed genome-wide admixture mapping to identify regions whereby local African or European ancestry is associated with BDR in African Americans. We identified a population-specific association with an intergenic SNP on chromosome 9q21 that was significantly associated with BDR (rs73650726, p = 7.69 × 10−9). A trans-ethnic meta-analysis across African Americans and Latinos identified three additional SNPs within the intron of PRKG1 that were significantly associated with BDR (rs7903366, rs7070958 and rs7081864, p ≤ 5 × 10−8). Our results failed to replicate in three additional populations of 416 Latinos and 1615 African Americans. Our findings indicate that both population-specific and shared genetic variation contributes to differences in BDR in minority children with asthma, and that the genetic underpinnings of BDR may differ between racial/ethnic groups.
Effectiveness of beta blockers in patients with and without a history of myocardial infarction
PurposeStudies demonstrating mortality benefit of beta blockers (BB) after myocardial infarction (MI) were conducted before the era of percutaneous intervention and widespread use of statins. Recent retrospective studies show inconsistent results regarding which subgroups of coronary artery disease (CAD) patients’ benefit. Most studies did not account for medication changes over time. We evaluated the association of time-varying BB exposure with death in CAD patients with or without a history of MI.MethodsThis retrospective cohort study included all patients with MI and those with coronary disease but no MI at a single health care system who also had health insurance from January 1, 1997, to June 30, 2011. Pharmacy claims data were used to estimate BB exposure over 6-month rolling windows. The primary endpoint was all-cause death. The effect of BB exposure was tested using time-updated Cox proportional hazards models.ResultsWe identified 6220 patients with MI and 21,285 patients with CAD but no MI. Among patients who suffered MI, BB exposure was associated with a 31% relative risk reduction in all-cause death (hazard ratio [HR] 0.69, P = 0.001). Among subjects who survived 3 years after MI, BB retained a protective association (HR 0.71, P = 0.001). Among CAD-only patients, BB exposure was also associated with risk reduction (HR 0.85, P = 0.001).ConclusionAmong patients with CAD, BB exposure is associated with reduced risk of death. The association is strongest among those who have suffered MI. This favorable association appears durable beyond 3 years.
Clinical Outcomes and Adherence to Medications Measured by Claims Data in Patients With Diabetes
Clinical Outcomes and Adherence to Medications Measured by Claims Data in Patients With Diabetes Manel Pladevall , MD, MS 1 , L. Keoki Williams , MD, MPH 1 , Lisa Ann Potts , PHARMD 2 , George Divine , PHD 3 , Hugo Xi , MD 1 and Jennifer Elston Lafata , PHD 1 1 Center for Health Services Research, Henry Ford Health System, Detroit, Michigan 2 College of Pharmacy, University of Michigan, Ann Arbor, Michigan 3 Department of Biostatistics and Research Epidemiology, Henry Ford Health System, Detroit, Michigan Address correspondence and reprint requests to Dr. Manel Pladevall, MD, MS, Center for Health Services Research, Henry Ford Health System, One Ford Place, Suite 3A, Detroit, Michigan 48202. E-mail: mpladev1{at}hfhs.org Abstract OBJECTIVE —Although poor medication adherence may contribute to inadequate diabetes control, ways to feasibly measure adherence in routine clinical practice have yet to be established. The present study was conducted to determine whether pharmacy claims-based measures of medication adherence are associated with clinical outcomes in patients with diabetes. RESEARCH DESIGN AND METHODS —The study setting was a large, integrated delivery and financial system serving the residents of southeastern Michigan. The study population consisted of 677 randomly selected patients aged ≥18 years with a diagnosis of diabetes, hypercholesterolemia, and hypertension and who filled at least one prescription for either an antidiabetic, lipid-lowering, or antihypertensive drug in each of the 3 study years (1999–2001). The main outcome measures were HbA 1c , LDL cholesterol levels, and blood pressure. RESULTS —Nonadherent patients had both statistically and clinically worse outcomes than adherent patients. Even after adjusting for demographic and clinical characteristics, nonadherence was significantly associated with HbA 1c and LDL cholesterol levels. A 10% increase in nonadherence to metformin and statins was associated with an increase of 0.14% in HbA 1c and an increase of 4.9 mg/dl in LDL cholesterol levels. Nonadherence to ACE inhibitors was not significantly associated with blood pressure. CONCLUSIONS —Claims-based measures of medication adherence are associated with clinical outcomes in patients with diabetes and may therefore prove to be useful in clinical practice. More research is needed on methods to introduce claims-based adherence measurements into routine clinical practice and how to use these measurements to effectively improve adherence and health outcomes in chronic care management. CMG, continuous measure of medication gaps SBP, systolic blood pressure Footnotes A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances. Accepted August 10, 2004. Received April 17, 2004. DIABETES CARE