In the past my research focused on the physical sciences, molecular evolutionary
genetics and methods of analyzing gene expression data. My undergraduate work was done at
UC Davis and I hold a Ph.D. from UC Irvine. Much of my dissertation involved
investigating the patterns of coding region substitution variability (ways of measuring
the variability, empirical studies of the variability in mammals and hypothesis testing)
in an attempt to better understand the nature of population genetic models that might
give rise to such patterns. Interestingly, the dispersion index was found to
significantly increase over time for mammals. (This work was done in collaboration with
John Gillespie, Dick Hudson and Walter Fitch.) I also developed and analyzed stochastic
models of haploid evolution and led a substantial effort to develop computational methods
to address the analysis of shared chromosomal regions in extremely large and complex
extended families with segregating disease variants (collaborators: Ray White, Nori
Matsunami, Veronica Garcia and Hywel Jones). 

I'm currently a tenure-track research scientist at the Marshfield Clinic Research
Foundation at the Center for Human Genetics. My lab focuses on both experimental work
mapping disease genes as well as genetics theory and applied probability. Understanding
the genetics underlying variation in Th17-mediated activity and the causes of aberrant,
pathogenic IL-23/IL-17 signaling is a central aim of my empirical research. With regard
to theory, my lab is currently investigating sequencing analysis methods, large-scale
simulation of disease models in distantly-related individuals, and the decay of linkage
disequilibrium from disease-causing variants. 

Prior to my position at Marshfield, I was a senior staff scientist at Celera, located in
Alameda, CA. My primary interests there centered around applying mathematical and
statistical methods to investigate interesting questions in genetics, better understand
genetic processes, and construct genetics theory. Among the projects I have recently
worked on include disease-gene mapping, whole-genome association mapping methods, fine
mapping approaches, genetic prognostic theory, Bayesian methodology and application of
population genetics to disease mapping. Further, I attempt to keep active in genetics
theory, empirical experiments (particularly those related to disease traits), and
statistical methods, primarily probability-based, connecting the two for it is my view
that a robust interplay between these three aspects of science is the engine behind
robust scientific progress. 

I am also involved in many empirical studies of common-disease genetics, largely
revolving around genome-wide association approaches and extended family linkage studies.
The majority of my work in this area has concentrated on mapping autoimmune and
autoinflammatory diseases. With the collaboration of my colleagues, these efforts have
resulted in several findings including the R620W missense SNP in the protein tyrosine
phosphatase PTPN22 and 9q33.2-linked variants residing in the TNF receptor factor
adaptor-encoding TRAF1 gene being correlated with rheumatoid arthritis; and several
polymorphisms within cytokine-related genes – two missense SNPs (L310P and Q381R) in
IL23R, haplotypes in IL12B, and SNPs in IL13 – being in linkage disequilibrium with
psoriasis vulgaris (collaborators: Joe Catanese, Victoria Carlton, Ann Begovich, Peter
Gregersen, Mike Seldin, Lindsey Criswell, Ellen Beasley, Linda McAllister, Michele
Cargill, Monica Chang, Veronica Garcia, Jerry Krueger, Kristina Callis Duffin, Nori
Matsunami, Mark Leppert, Lineagen, John Sninsky). All of these disease-association
findings have been independently replicated by other investigators. In addition, I have
worked on association studies for neurodegenerative diseases, hepatic fibrosis
progression, and fatty liver diseases (collaborators: Andrew Grupe, Yonghong Li, Anand
Chokkalingam, John Sninsky). Recently I've looked into copy-number variation
(collaborators: Andrew Grupe, Charley Rowland). 

Aside from those topics listed above, I am also interested in other fields including: 

(1) The fundamentals of probability theory and statistical inference 

(2) Anthropological genetics 

(3) The mathematics of self-reproducing systems 

(4) Analytic philosophy, foundations of science and the philosophy of language 

Steve Schrodi 

Associate Research Scientist Center for Human Genetics Marshfield Clinic Research

Principal Investigator University of Wisconsin-Institute for Clinical and Translational

Disease Gene Mapping, Psoriasis, IL12/23


Detailed genetic characterization of the interleukin-23 receptor in psoriasis, Genes & Immunity (2008)

Using a multi-tiered, case-control association design, scanning 25,215 gene-centric SNPs, we previously identified two psoriasis...



Detailed genetic characterization of the psoriasis-associated gene IL12B to further define the causal variant(s), Society for Investigative Dermatology (2007)

A multi-tiered, case-control association study using a collection of over 25,000 gene-centric SNPs, identified association...



Genetic characterization of the psoriasis-associated gene IL23R, Society of Investigative Dermatology (2007)

Using a multi-tiered, case-control association design, scanning over 25,000 gene-centric SNPs, we recently identified two...



A large-scale genetic association study confirms IL12B and leads to the identification of IL23R as psoriasis risk genes (with Michele Cargill, Monica Chang, Veronica E. Garcia, Rhonda Brandon, Kristina P. Callis, Nori Matsunami, Kristin G. Ardlie, Lee A. Honigberg, Daniel Civello, Joseph J. Catanese, Diane U. Leong, Jackie M. Panko, Linda B. McAllister, Christopher B. Hansen, Jason Papenfuss, Stephen M. Prescott, Thomas J. White, Mark F. Leppert, Gerald G. Krueger, and Ann B. Begovich), American Journal of Human Genetics (2006)

We performed a multi-tiered, case-control association study of psoriasis in three independent, white North American...


Disease Gene Mapping, Psoriasis, IL13


Association between IL13 polymorphisms and psoriatic arthritis is modified by smoking, J Invest Dermatol (2009)

Genetic and environmental factors influence the development of psoriasis (Ps) and psoriatic arthritis (PsA). Recently,...



The 5q31 variants associated with psoriasis and Crohn's disease are distinct, Human Molecular Genetics (2008)

Predisposition to psoriasis is known to be affected by genetic variation in HLA-C, IL12B and...



Variants in the 5q31 cytokine gene cluster are associated with psoriasis, Genes and Immunity (2007)

Following a staged functional SNP scan involving 25,215 markers, we report the findings of three...


Disease Gene Mapping, Psoriasis, Other loci


Multiple Loci within the Major Histocompatibility Complex Confer Risk of Psoriasis (with Bing-Jian Feng, Liang-Dan Sun, Razieh Soltani-Arabshahi, Anne M. Bowcock, Rajan P. Nair, Philip Stuart, James T. Elder, Ann B. Begovich, Goncalo R. Abecasis, Xue-Jun Zhang, Kristina P. Callis Duffin, Gerald G. Krueger, and David E. Goldgar), PLoS Genetics (2009)

Psoriasis is a common inflammatory skin disease characterized by thickened scaly red plaques. Previously we...



Genome-wide scan reveals association of psoriasis with IL-23 and NF-B pathways (with Rajan P. Nair, Kristina C. Duffin, Cynthia Helms, Jun Ding, Philip E. Stuart, David Goldgar, Johann E. Gudjonsson, Yun Li, Trilokraj Tejasvi, Bing-Jiag Feng, Andreas Ruether, Stefan Schreiber, Michael Weichenthal, Dafna Gladman, Proton Rahman, Sampath Prahalad, Stephen L. Guthery, Judith Fischer, Wilson Liao, Pui-Yan Kwok, Alan Menter, G Mark Lathrop, Carol A. Wise, Ann B. Begovich, John J. Voorhees, James T. Elder, Gerald G. Krueger, Anne M. Bowcock, and Goncalo R. Abecasis), Nature Genetics (2009)

Psoriasis is a common immune-mediated disorder that affects the skin, nails and joints. To identify...



Further Genetic Evidence for Three Psoriasis-Risk Genes: ADAM33, CDKAL1, and PTPN22 (with Yonghong Li, Wilson Liao, Monica Chang, Nam Bui, Joseph J. Catanese, Annie Poon, Nori Matsunami, Kristina P. Callis-Duffin, Mark F. Leppert, Anne M. Bowcock, Pui-Yan Kwok, Gerald G. Krueger, and Ann B. Begovich), Journal Investigative Dermatology (2008)

Predisposition to psoriasis is known to be affected by genetic variation in HLA-C, IL12B, and...



Genome-wide Association Scan in Psoriasis: New Insights into Chronic Inflammatory Disease Biology, Expert Reviews in Clinical Immunology (2008)

Evaluation of: Liu Y, Helms C, Liao W et al. A genome-wide association study of...



Characterizing susceptibility to phenotypic variations of psoriasis by comparing allelic association signals on chromosome 6 (with J Panko, B Wong, K Callis, N Matsunami, M A. Cargill, and G G. Krueger), Genes to Clinic Conference (2005)

Though the existence of a genetic component of psoriasis can be easily observed, the genes...


Disease Gene Mapping, Neurodegeneration, Parkinsons


Neither replication nor simulation supports a role for the axon guidance pathway in the genetics of Parkinson's disease (with Yonghong Li, Charles Rowland, Georgia Xiromerisiou, Robert J. Lagier, Efthimios Dradiotis, David Ross, Nam Bui, Joseph Catanese, Konstantinos Aggelakis, Andrew Grupe, and Georgios Hadjigeorgiou), PLoS ONE (2008)

Susceptibility to sporadic Parkinson’s disease (PD) is thought to be influenced by both genetic and...



Genetic evidence for ubiquitin-specific proteases USP24 and USP40 as candidate genes for late-onset Parkinson disease (with Yonghong Li, Charles Rowland, Kristina Tacey, Joseph Catanese, and Andrew Grupe), Human Mutation (2006)

Linkage studies have defined susceptibility regions for late-onset Parkinson disease (PD) on chromosomes 1 and...



A case-control association study of the 12 single-nucleotide polymorphisms implicated in Parkinson disease by a recent genome scan (with Yonghong Li, Charles Rowland, Walter Laird, Kristina Tacey, David Ross, Diane Leong, Joseph Catanese, John Sninsky, and Andrew Grupe), American Journal of Human Genetics (2006)

Disease Gene Mapping, Neurodegeneration, Alzheimers


Association of late-onset Alzheimer's disease with genetic variation in multiple members of the GAPD gene family (with Yonghong Li, Petra Nowotny, Peter Holmans, Scott Smemo, John S. K. Kauwe, Anthony L. Hinrichs, Kristina Tacey, Lisa Doil, Ryan van Luchene, Veronica Garcia, Charles Rowland, Diane Leong, Goran Gogic, Joanne Chan, Anibal Cravchik, David Ross, Kit Lau, Shirley Kwok, Sheng-Yung Chang, Joe Catanese, John Sninsky, Thomas J. White, John Hardy, John Powell, Simon Lovestone, John C. Morris, Leon Thal, Michael Owen, Julie Williams, Alison Goate, and Andrew Grupe), Proc Natl Acad Sci USA (2004)

Although several genes have been implicated in the development of the early-onset autosomal dominant form...



Association of ABCA1 with late-onset Alzheimer's disease is not observed in a case-control study, Neuroscience Letters (2004)

Genetic association of ABCA1 or the ATP-binding cassette A1 transporter with late-onset Alzheimer’s disease (LOAD)...


Disease Gene Mapping, Rheumatoid Arthritis PTPN22


PTPN22 genetic variation: evidence for multiple variants associated with rheumatoid arthritis (with Victoria E. H. Carlton, Xiaolan Hu, Anand P. Chokkalingam, Rhonda Brandon, Heather C. Alexander, Monica Chang, Joseph J. Catanese, Diane U. Leong, Kristin G. Ardlie, Daniel L. Kastner, Michael F. Seldin, Lindsey A. Criswell, Peter K. Gregersen, Ellen Beasley, Glenys Thomson, Christopher I. Amos, and Ann B. Begovich), American Jounral of Human Genetics (2005)

The minor allele of the R620W missense single-nucleotide polymorphism (SNP) (rs2476601) in the hematopoietic-specific protein...



A missense single-nucleotide polymorphism in a gene encoding a protein tyrosine phosphatase (PTPN22) is associated with rheumatoid arthritis (with Ann B. Begovich, Victoria E. H. Carlton, Lee A. Honigberg, Anand P. Chokkalingam, Heather C. Alexander, Kirstin G. Ardlie, Qiqing Huang, Ashley M. Smith, Jill M. Spoerke, Marion T. Conn, Monica Chang, Sheng-Yung P. Chang, Randall K. Saiki, Joseph J. Catanese, Diane U. Leong, Veronica E. Garcia, Linda B. McAllister, Douglas A. Jeffery, Annette T. Lee, Franak Batliwalla, Elaine Remmers, Lindsey A. Criswell, Michael F. Seldin, Daniel L. Kastner, Christopher I. Amos, John J. Sninsky, and Peter K. Gregersen), American Journal of Human Genetics (2004)

Rheumatoid arthritis (RA) is the most common systemic autoimmune disease, affecting approximately 1% of the...


Disease Gene Mapping, Rheumatoid Arthritis 9q33


A large-scale rheumatoid arthritis genetic study identifies association at chromosome 9q33.2, PLoS Genetics (2008)

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease affecting both joints and extra-articular tissues....



A Candidate Gene Approach Identifies the TRAF1/C5 Region as a Risk Factor for Rheumatoid Arthritis (with Fina A.S. Kurreeman, Leonid Padyukov, Rute B. Marques, Maria Seddighzadeh, Gerrie Stoeken-Rijsbergen, Annette H.M. van der Helm-van Mil, Cornelia F. Allaart, Willem Verduyn, Jeanine Houwing-Duistermaat, Ann B. Begovich, Lars Klareskog, Tom W. J. Huizinga, and Rene E. M. Toes), PLoS Medicine (2007)

Disease Gene Mapping, Rheumatoid Arthritis, Other loci


Meta-analysis evidence of a differential risk of the FCRL3 -169T->C polymorphism in white and East Asian rheumatoid arthritis patients (with Begovich Ann and Chang Monica), Arthritis & Rheumatism (2007)

Association between a functional promoter polymorphism (rs7528684) in the Fc receptor-like gene, FCRL3, and rheumatoid...


Disease Gene Mapping, HCV Hepatic fibrosis


Identification of two gene variants associated with risk of advanced fibrosis in patients with chronic hepatitis C (with Hongin Huang, M L. Shiffman, R C. Cheung, T J. Layden, S Friedman, O T. Abar, L Yee, Anand Chokkalingam, Jason Chan, Joseph J. Catanese, Diane U. Leong, David Ross, Xiaolan Hu, A Monto, Linda B. McAllister, Sam Broder, Tom White, John J. Sninsky, and T L. Wright), Gastroenterology (2006)

BACKGROUND & AIMS: Previously identified clinical risk factors such as sex, alcohol consumption, and age...



Association of Fibrosis Risk in HCV Patients with a Missense SNP in Gene CPT1A (with H Huang, T L. Wright, R C. Cheung, T J. Layden, O Tuason, L Yee, A P. Chakkalingam, J Chan, J J. Catanese, D U. Leong, R Emerson, A Monto, L B. McAllister, J J. Sninsky, and M L. Shiffman), EASL (2005)

Disease Gene Mapping, Non-alcoholic Steatohepatitis

Probability, Statistics and Analysis Methods

A Probabilistic Approach to Large-Scale Association Scans: A Semi-Bayesian Method to Detect Disease-Predisposing Alleles, Statistical Applications in Genetics and Molecular Biology (2005)

Recent analytic and technological breakthroughs have set the stage for genome-wide linkage disequilibrium studies to...



Selecting Tagging SNPs for Association Studies Using Power Calculations from Genotype Data (with Xiaolan Hu, David A. Ross, and Michele Cargill), Human Heredity (2004)

Recent studies have indicated that linkage disequilibrium (LD) between single nucleotide polymorphism (SNP) markers can...



Calculating exact P-values for the Transmission/Disequilibrium Test (with Hywel B. Jones) (2003)

The transmission/disequilibrium test (TDT) has become a popular method for analyzing genetic association studies. It...


Genetics Theory


Pairwise linkage disequilibrium under disease models (with Veronica E. Garcia, Charles Rowland, and Hywel B. Jones), European Journal of Human Genetics (2006)

Many genetic studies of disease association rely heavily on linkage disequilibrium (LD) patterns between pairs...



Population Genetics


Genome wide survey for common polymorphisms in human genes, Cold Spring Harbor Conference (2003)

The completion of the human genome sequence allows an opportunity for focused exploration of particular...



A modification to the standard model of haploid population genetics for small population sizes , UMI (2001)

This dialogue is concerned with improving the standard model of haploid population genetics. It is...


Planetary Geology


Influence of electrostatic charges on the movement of dust by wind (with Rodman N. Leach and Ronald Greeley) (1992)

No subject area