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A Common Variant in CLDN14 is Associated with Primary Biliary Cirrhosis and Bone Mineral Density. - Scientific reports
Primary biliary cirrhosis (PBC), a chronic autoimmune liver disease, has been associated with increased incidence of osteoporosis. Intriguingly, two PBC susceptibility loci identified through genome-wide association studies are also involved in bone mineral density (BMD). These observations led us to investigate the genetic variants shared between PBC and BMD. We evaluated 72 genome-wide significant BMD SNPs for association with PBC using two European GWAS data sets (nâ€‰=â€‰8392), with replication of significant findings in a Chinese cohort (685 cases, 1152 controls). Our analysis identified a novel variant in the intron of the CLDN14 gene (rs170183, Pfdrâ€‰=â€‰0.015) after multiple testing correction. The three associated variants were followed-up in the Chinese cohort; one SNP rs170183 demonstrated consistent evidence of association in diverse ethnic populations (Pcombinedâ€‰=â€‰2.43â€‰Ã—â€‰10(-5)). Notably, expression quantitative trait loci (eQTL) data revealed that rs170183 was correlated with a decline in CLDN14 expression in both lymphoblastoid cell lines and T cells (Padjâ€‰=â€‰0.003 and 0.016, respectively). In conclusion, our study identified a novel PBC susceptibility variant that has been shown to be strongly associated with BMD, highlighting the potential of pleiotropy to improve gene discovery.
Genome-wide Association Study of Late-Onset Myasthenia Gravis: Confirmation of TNFRSF11A, and Identification of ZBTB10 and Three Distinct HLA Associations. - Molecular medicine (Cambridge, Mass.)
To investigate the genetics of late-onset myasthenia gravis (LOMG), we conducted a genome-wide association study imputation of >6 million SNPs in 532 LOMG cases (anti-acetylcholine receptor (AChR) antibody positive, onset age â‰¥50 years) and 2,128 controls matched for sex and population substructure. The data confirm reported TNFRSF11A associations [rs4574025, P = 3.9Ã—10(-07), odds ratio (OR) = 1.42] and identify a novel candidate gene, ZBTB10, achieving genome-wide significance (rs6998967, P = 8.9Ã—10(-10), OR = 0.53). Several other SNPs showed suggestive significance including rs2476601 (P = 6.5Ã—10(-06), OR =1.62) encoding the PTPN22 R620W variant noted in early-onset MG (EOMG) and other autoimmune diseases. In contrast, EOMG-associated SNPs in TNIP1 showed no association in LOMG, nor did other loci suggested for EOMG. Many SNPs within the major histocompatibility complex (MHC) region showed strong associations in LOMG, but with smaller effect sizes than in EOMG (highest OR ~2 vs. ~6 in EOMG). Moreover, the strongest associations were in opposite directions from EOMG, including an OR of 0.54 for DQA1*05:01 in LOMG (P = 5.9Ã—10(-12)) vs. 2.82 in EOMG (P = 3.86Ã—10(-45)). Association and conditioning studies for the MHC region showed three distinct and largely independent association peaks for LOMG corresponding to i) MHC class II (highest attenuation when conditioning on DQA1), ii) HLA-A and iii) MHC class III SNPs. Conditioning studies of HLA amino acid residues also suggest potential functional correlates. Together, these findings emphasize the value of subgrouping MG patients for clinical and basic investigations, and imply distinct predisposing mechanisms in LOMG.
International genome-wide meta-analysis identifies new primary biliary cirrhosis risk loci and targetable pathogenic pathways. - Nature communications
Primary biliary cirrhosis (PBC) is a classical autoimmune liver disease for which effective immunomodulatory therapy is lacking. Here we perform meta-analyses of discovery data sets from genome-wide association studies of European subjects (n=2,764 cases and 10,475 controls) followed by validation genotyping in an independent cohort (n=3,716 cases and 4,261 controls). We discover and validate six previously unknown risk loci for PBC (Pcombined<5 Ã— 10(-8)) and used pathway analysis to identify JAK-STAT/IL12/IL27 signalling and cytokine-cytokine pathways, for which relevant therapies exist.
The genetics of human autoimmune disease: A perspective on progress in the field and future directions. - Journal of autoimmunity
Progress in defining the genetics of autoimmune disease has been dramatically enhanced by large scale genetic studies. Genome-wide approaches, examining hundreds or for some diseases thousands of cases and controls, have been implemented using high throughput genotyping and appropriate algorithms to provide a wealth of data over the last decade. These studies have identified hundreds of non-HLA loci as well as further defining HLA variations that predispose to different autoimmune diseases. These studies to identify genetic risk loci are also complemented by progress in gene expression studies including definition of expression quantitative trait loci (eQTL), various alterations in chromatin structure including histone marks, DNase I sensitivity, repressed chromatin regions as well as transcript factor binding sites. Integration of this information can partially explain why particular variations can alter proclivity to autoimmune phenotypes. Despite our incomplete knowledge base with only partial definition of hereditary factors and possible functional connections, this progress has and will continue to facilitate a better understanding of critical pathways and critical changes in immunoregulation. Advances in defining and understanding functional variants potentially can lead to both novel therapeutics and personalized medicine in which therapeutic approaches are chosen based on particular molecular phenotypes and genomic alterations.Copyright Â© 2015 Elsevier Ltd. All rights reserved.
Genome-Wide Association and Trans-ethnic Meta-Analysis for Advanced Diabetic Kidney Disease: Family Investigation of Nephropathy and Diabetes (FIND). - PLoS genetics
Diabetic kidney disease (DKD) is the most common etiology of chronic kidney disease (CKD) in the industrialized world and accounts for much of the excess mortality in patients with diabetes mellitus. Approximately 45% of U.S. patients with incident end-stage kidney disease (ESKD) have DKD. Independent of glycemic control, DKD aggregates in families and has higher incidence rates in African, Mexican, and American Indian ancestral groups relative to European populations. The Family Investigation of Nephropathy and Diabetes (FIND) performed a genome-wide association study (GWAS) contrasting 6,197 unrelated individuals with advanced DKD with healthy and diabetic individuals lacking nephropathy of European American, African American, Mexican American, or American Indian ancestry. A large-scale replication and trans-ethnic meta-analysis included 7,539 additional European American, African American and American Indian DKD cases and non-nephropathy controls. Within ethnic group meta-analysis of discovery GWAS and replication set results identified genome-wide significant evidence for association between DKD and rs12523822 on chromosome 6q25.2 in American Indians (P = 5.74x10-9). The strongest signal of association in the trans-ethnic meta-analysis was with a SNP in strong linkage disequilibrium with rs12523822 (rs955333; P = 1.31x10-8), with directionally consistent results across ethnic groups. These 6q25.2 SNPs are located between the SCAF8 and CNKSR3 genes, a region with DKD relevant changes in gene expression and an eQTL with IPCEF1, a gene co-translated with CNKSR3. Several other SNPs demonstrated suggestive evidence of association with DKD, within and across populations. These data identify a novel DKD susceptibility locus with consistent directions of effect across diverse ancestral groups and provide insight into the genetic architecture of DKD.
TYK2 protein-coding variants protect against rheumatoid arthritis and autoimmunity, with no evidence of major pleiotropic effects on non-autoimmune complex traits. - PloS one
Despite the success of genome-wide association studies (GWAS) in detecting a large number of loci for complex phenotypes such as rheumatoid arthritis (RA) susceptibility, the lack of information on the causal genes leaves important challenges to interpret GWAS results in the context of the disease biology. Here, we genetically fine-map the RA risk locus at 19p13 to define causal variants, and explore the pleiotropic effects of these same variants in other complex traits. First, we combined Immunochip dense genotyping (n = 23,092 case/control samples), Exomechip genotyping (n = 18,409 case/control samples) and targeted exon-sequencing (n = 2,236 case/controls samples) to demonstrate that three protein-coding variants in TYK2 (tyrosine kinase 2) independently protect against RA: P1104A (rs34536443, OR = 0.66, P = 2.3 x 10(-21)), A928V (rs35018800, OR = 0.53, P = 1.2 x 10(-9)), and I684S (rs12720356, OR = 0.86, P = 4.6 x 10(-7)). Second, we show that the same three TYK2 variants protect against systemic lupus erythematosus (SLE, Pomnibus = 6 x 10(-18)), and provide suggestive evidence that two of the TYK2 variants (P1104A and A928V) may also protect against inflammatory bowel disease (IBD; P(omnibus) = 0.005). Finally, in a phenome-wide association study (PheWAS) assessing >500 phenotypes using electronic medical records (EMR) in >29,000 subjects, we found no convincing evidence for association of P1104A and A928V with complex phenotypes other than autoimmune diseases such as RA, SLE and IBD. Together, our results demonstrate the role of TYK2 in the pathogenesis of RA, SLE and IBD, and provide supporting evidence for TYK2 as a promising drug target for the treatment of autoimmune diseases.
Multiple genetic variants associated with primary biliary cirrhosis in a Han Chinese population. - Clinical reviews in allergy & immunology
Multiple genome-wide association studies of primary biliary cirrhosis (PBC) in both European and Japanese ancestries have shown significant associations of many genetic loci contributing to the susceptibility to PBC. Major differences in susceptibility loci between these two population groups were observed. In this study, we examined whether the most significant loci observed in either European and/or Japanese cohorts are associated with PBC in a Han Chinese population. In 1070 PBC patients and 1198 controls, we observed highly significant associations at CD80 (rs2293370, Pâ€‰=â€‰2.67â€‰Ã—â€‰10(-8)) and TNFSF15 (rs4979462, Pâ€‰=â€‰3.86â€‰Ã—â€‰10(-8)) and significant associations at 17q12-21 (rs9303277), PDGFB (rs715505), NF-ÎºB1 (rs7665090), IL12RB2 (rs11209050), and STAT4 (rs7574865; all corrected P values <0.01). However, no association was observed for POU2AF1 (rs4938534), IL12A (rs485499 and rs2366408), IL7R (rs6897932), CXCR5 (rs715412), SOCS1 (rs725613), and TNFRSF1A (rs1800693). STAT4 (rs7574865) was strongly associated after additional control samples were analyzed. Our study is the first large-scale genetic analysis in a Han Chinese PBC cohort. These results do not only reflect that Han Chinese PBC patients share common genetic susceptibility genes with both their Japanese and European counterparts but also suggest a distinctly different genetic susceptibility profile.
Relationship between glaucoma and admixture in postmenopausal African American women. - Ethnicity & disease
To investigate the association between African admixture and glaucoma prevalence among African American women.Participants included 11616 African American women from the Women's Health Initiative Study (WHI) for whom admixture information was available and included 2548 who self-reported a diagnosis of glaucoma.Glaucoma.Significant association was observed between self-identified glaucoma status and admixture. However, this association was not significant in a model that included neighborhood socioeconomic status (NSES), hypertension, diabetes and body mass index (BMI). Self-identified glaucoma status was associated with diabetes that persisted after adjustment for admixture, NSES, hypertension, and BMI. Lower NSES was also associated with higher glaucoma risk but this association was marginal in the fully adjusted model and neither hypertension nor BMI showed association. When glaucoma status was limited to those reporting use or no use of appropriate ophthalmologic medication, no associations were observed in any of the models.This study failed to find an independent association of glaucoma status and African admixture and these findings suggest that the higher frequency glaucoma in African Americans may be largely due to other factors.
Genome-wide analysis of DNA methylation, copy number variation, and gene expression in monozygotic twins discordant for primary biliary cirrhosis. - Frontiers in immunology
Primary biliary cirrhosis (PBC) is an uncommon autoimmune disease with a homogeneous clinical phenotype that reflects incomplete disease concordance in monozygotic (MZ) twins. We have taken advantage of a unique collection consisting of genomic DNA and mRNA from peripheral blood cells of female MZ twins (nâ€‰=â€‰3 sets) and sisters of similar age (nâ€‰=â€‰8 pairs) discordant for disease. We performed a genome-wide study to investigate differences in (i) DNA methylation (using a custom tiled four-plex array containing tiled 50-mers 19,084 randomly chosen methylation sites), (ii) copy number variation (CNV) (with a chip including markers derived from the 1000 Genomes Project, all three HapMap phases, and recently published studies), and/or (iii) gene expression (by whole-genome expression arrays). Based on the results obtained from these three approaches we utilized quantitative PCR to compare the expression of candidate genes. Importantly, our data support consistent differences in discordant twins and siblings for the (i) methylation profiles of 60 gene regions, (ii) CNV of 10 genes, and (iii) the expression of 2 interferon-dependent genes. Quantitative PCR analysis showed that 17 of these genes are differentially expressed in discordant sibling pairs. In conclusion, we report that MZ twins and sisters discordant for PBC manifest particular epigenetic differences and highlight the value of the epigenetic study of twins.
Socioeconomic status and lung cancer: unraveling the contribution of genetic admixture. - American journal of public health
We examined the relationship between genetic ancestry, socioeconomic status (SES), and lung cancer among African Americans and Latinos.We evaluated SES and genetic ancestry in a Northern California lung cancer case-control study (1998-2003) of African Americans and Latinos. Lung cancer case and control participants were frequency matched on age, gender, and race/ethnicity. We assessed case-control differences in individual admixture proportions using the 2-sample t test and analysis of covariance. Logistic regression models examined associations among genetic ancestry, socioeconomic characteristics, and lung cancer.Decreased Amerindian ancestry was associated with higher education among Latino control participants and greater African ancestry was associated with decreased education among African lung cancer case participants. Education was associated with lung cancer among both Latinos and African Americans, independent of smoking, ancestry, age, and gender. Genetic ancestry was not associated with lung cancer among African Americans.Findings suggest that socioeconomic factors may have a greater impact than genetic ancestry on lung cancer among African Americans. The genetic heterogeneity and recent dynamic migration and acculturation of Latinos complicate recruitment; thus, epidemiological analyses and findings should be interpreted cautiously.
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