Human Genetics

Ben Darbro M.D., Ph.D.

Current
Ben
Darbro
M.D., Ph.D.
Assistant Professor, Director of the Shivanand R. Patil Cytogenetics and Molecular Laboratory
Pediatrics
Research area(s): 
Genetic Determinants of Intellectual Disability
Address
Research
Research Focus: 

My primary research interest is in the genetic determinants of intellectual disability (ID), formerly referred to as mental retardation (MR).  I specifically study the roles of copy number variation and somatic structural variation in the context of a “genomic mutational burden” hypothesis of ID.  This hypothesis is investigated using a combination of conventional cytogenetics methods (chromosome analysis and fluorescence in situ hybridization) and new molecular, high throughput, and high data volume, genomic technologies including single nucleotide polymorphism (SNP) arrays, gene expression microarrays, comparative genomic hybridization (CGH) arrays as well as custom targeted, whole exome, and whole genome massively parallel DNA sequencing.  We perform all our own bioinformatics and are actively engaged in the development of new analysis tools to better meet our needs and those of the scientific community.  Drosophila melanogaster and the well-established GAL4/UAS/RNAi system are used to evaluate candidate ID genes with the use of a validated olfaction learning technique (T-Maze).  Candidate genes are derived from our extensive clinical database of patients with ID that have already undergone diagnostic chromosomal microarray testing.

Virginia L. Willour Ph.D.

Current
Virginia
L.
Willour
Ph.D.
Associate Professor
Psychiatry
Research area(s): 
Human Genetics & Neurogenetics
Address
B002J
ML
B002
ML
Research
Research Focus: 

Identifying genetic and epigenetic risk factors for suicidal behavior

The primary goal of our laboratory is to identify genetic and epigenetic risk factors for suicidal behavior.  Family, twin, and adoption studies make clear that suicidal behavior has a substantial heritable component. While there is evidence that this heritability is accounted for in part by a liability to mood disorder, other evidence suggests an independent heritable facet that may cut across multiple psychiatric disorders.  In an effort to better understand the biological basis of this behavior, we have conducted a genome-wide association study (GWAS) using attempted suicide as the phenotype, an effort that identified a promising association signal on 2p25 as well as candidate genes implicating the Wnt signaling pathway and excitatory neurotransmission.  These findings have prompted us to launch a large-scale whole exome sequencing project, with the goal of identifying functional variants associated with suicidal behavior on 2p25 and throughout the genome.  Environmental stressors, such as child abuse and early parental loss, are also known to play important roles in triggering suicidal behavior, likely through interaction with genetic vulnerability factors.  With this in mind, we have begun an epigenetics project that involves assessing genome-wide methylation patterns in post-mortem brains of suicide completers and controls, with the goal of identifying differentially methylated candidate genes and regions associated with suicidal behavior.

Faculty affiliations: 

Robert F Mullins Ph.D.

Current
Robert
F
Mullins
Ph.D.
Professor
Ophthalmology & Visual Sciences
Address
4135E
MERF
4120
MERF
Research
Research Focus: 
  • Biology and pathology of the choroidal microvasculature in aging and macular disease
  • Mechanisms involved in the development of drusen, especially with regard to the role of humoral and cellular immune systems in drusen biogenesis
  • Structural and compositional changes in Bruch's membrane in aging and disease, and their effects on ocular physiology
  • Animal and in vitro models of age-related macular degeneration
  • Cell biology of inherited retinal diseases
Faculty affiliations: 

Markus H Kuehn Ph.D.

Current
Markus
H
Kuehn
Ph.D.
Associate Professor
Ophthalmology and Visual Sciences
Research area(s): 
Genetics of Optic Neuropathies
Address
4120F
MERF
4120
MERF
Research
Research Focus: 

My laboratory studies genetic factors that underlie or contribute to optic neuropathies - in particular glaucoma and the neurodegeneration associated with idiopathic intracranial hypertension (IIH).  Data from our studies have shown that components of the complement system are synthesized in the retina in glaucoma and that activation of complement accelerates retinal ganglion cell death.  In addition, variations in certain complement component genes appear to be associated with glaucoma.  A second area of interest is IIH.  The genetics of this condition and the cellular events that result in the degeneration of the retina are poorly understood. We are currently involved in a study designed to determine which genes are involved in the regulation of intracranial pressure and if certain genotypes are correlated with the development of the disease in human patients.

Faculty affiliations: 

Mary E Wilson M.D.

Current
Mary
E
Wilson
M.D.
    Professor
    Internal Medicine and Microbiology
    Research area(s): 
    Molecular Mechanisms of Host-parasite Interactions in Leishmaniasis
    Address
    SW34
    GH
    400
    EMRB
    Research
    Research Focus: 

    The protozoan parasite, Leishmania chagasi, causes the fatal human disease visceral leishmaniasis. L. chagasi express an abundant surface protease GP63, which is important for parasite survival. GP63 is encoded by >18 tandem MSP genes, falling into 3 homologous classes whose expression varies throughout the parasite life cycle. MSPL genes are expressed in logarithmic, whereas MSPS genes are expressed in stationary phase when parasites achieve maximal virulence and express high levels of GP63 protein. Our studies focus on the post-transcriptional mechanisms regulating expression of different MSP gene classes. These include mRNA T½, the efficiency of trans-splicing, and protein T½. Using reporter gene constructs and transfection techniques we are localizing unique sequences in MSP 3'UTRs that interact with regulatory proteins. Additionally, using MALDI-TOF mass spec we are examining products of specific MSP class genes that are expressed in different parasite stages.
    An ongoing epidemic of visceral leishmaniasis in northeast Brazil has led to our studies genetic loci associated with different outcomes of human L. chagasi infection (asymptomatic versus fatal). Using molecular genotyping methods (microsatellites, SSCP, RFLP, sequencing) we are examining polymorphic alleles of candidate genes for their contributions to disease susceptibility, in collaboration with Dr. Selma Jeronimo of Natal, Brazil. These studies will extend to a genome-wide scan and fine mapping of loci linked to different disease outcomes.

    John R Manak Ph.D.

    Current
    John
    R
    Manak
    Ph.D.
    Associate Professor
    Biology
    Research area(s): 
    Genetic basis of human disease using high-throughput genomics methodologies, fruit fly models of human disease and cancer.
    Address
    459A
    BB
    455=9A
    BB
    Research
    Research Focus: 

    Research in my laboratory covers three different but not mutually exclusive areas: 1) high-throughput genomics technologies to identify the genetic basis of human disease, 2) fruit fly models to understand human diseases such as epilepsy and cancer, with an emphasis on chromatin structure, 3) genomic technology development to facilitate identification of important mutations in both humans and model organisms. 

    For the first project, we are utilizing array-based comparative genomic hybridization (aCGH) to identify copy number variants associated with a number of diseases, including cleft lip and palate, spina bifida, and renal agenesis (all relatively common birth defects).  Using this approach, we identify genes whose copy number is altered in affected individuals, and we functionally validate these disease-associated genes in vertebrate animal models such as frogs and fish.  Additionally, we are using exome sequencing to explore the genetic basis of the aforementioned diseases.  This new genomics technology allows enrichment and high-throughput sequencing of the protein-coding exons in the human genome; since roughly 85% of the mutations causing Mendelian disorders are thought to reside in such exons, this strategy eliminates the need for costly whole-genome sequencing.  However, this type of analysis requires careful selection of pedigrees that show strong Mendelian inheritance patterns of the disease, which is turn suggest that high effect loci are at play in the disease process in these families. 

    For the second project, we are studying the Drosophila homolog of the c-Myb proto-oncogene (which causes leukemia and lymphoma in birds and mammals).  In particular, we are exploring the role of Drosophila Myb (Dm-Myb) in modulating chromatin structure and controlling gene expression.  Our recent results demonstrate that the Myb protein is controlling gene expression through its interaction with other chromatin-modulating factors, and that Myb is regulating different targets in different cell types.  Most interestingly, in contrast to the dogma in the field, Myb is a potent repressor of large numbers of genes in certain specialized cell types.

    Additionally, we are using the Drosophila system to model another human disease, myoclonic epilepsy.  We have shown for the first time that the same gene mutated in flies, mice and humans causes this form of epilepsy, and that the epileptic flies can be successfully treated with human anti-epileptic medications (Am J Hum Genet, 2011).  Intriguingly, the mutated gene is prickle, a gene that has been shown to be involved in establishing planar cell polarity.  A number of laboratories have worked on this gene over the course of many years with regard to its involvement in planar polarity; however, up until now the epileptic behavioral phenotype had been missed.        

    For the third project, we are developing a novel mutation mapping technology (in collaboration with my colleague in the dept, Josep Comeron) in order to efficiently and cost-effectively map both human disease-causing mutations as well as mutations of interest in a variety of model organisms, including mice and flies.  Currently, our technology can correctly identify known SNPs with an accuracy of 99% and we are now using the technology to identify novel mutations in several human diseases.    

    Faculty affiliations: 

    Thomas H Wassink M.D.

    Current
    Thomas
    H
    Wassink
    M.D.
    Professor
    Psychiatry
    Research area(s): 
    Human Genetics
    Address
    Research
    Research Focus: 

    My laboratory's goal is to identify genes that underlie susceptibility to a variety of psychiatric disorders, with our primary focus being autism. We use a variety of approaches in this endeavor, including positional cloning, sophisticated cytogenetic analyses, and candidate disease gene screening. We perform these studies in DNA obtained from numerous independent samples of families with multiple autistic individuals. We are also equipped to assess the function and expression of identified disease genes using an array of molecular and animal model techniques. Extensive additional resources and expertise are available to us here at Iowa through our collaborations with the Center for Statistical Genetics, the UIHC Cytogenetics laboratory, and the Center for Bioinformatics and Computational Biology. We are also actively investigating the genetics of panic disorder and schizophrenia. The panic disorder work uses traditional positional cloning methods and a sample of moderate to large panic disorder pedigrees. The schizophrenia genetics research is performed in association with the Department of Psychiatry's Mental Health Clinical Research Center. We collect DNA from individuals with schizophrenia, their families, and psychiatrically normal control subjects. All of these individuals participate in protocols that gather data from a wide variety of research domains, including functional and structural brain imaging, cognitive testing, disease phenomenology, longitudinal progression of disease, etc. The goal with the schizophrenia sample, therefore, is to investigate relationships between genetic information and these other types of data.

    Faculty affiliations: 

    Richard J Smith M.D.

    Current
    Richard
    J
    Smith
    M.D.
    Professor and Vice Chair
    Otolaryngology
    Research area(s): 
    Human Genetics
    Address
    Research
    Research Focus: 

    My laboratory is studying the genetic basis of deafness and membranoproliferative glomerulonephritis type 2 (MPGN 2). Hereditary deafness is common. It affects 1:2,000 newborns and accounts for greater than 50% of severe-to-profound childhood deafness. It also affects the elderly. Nearly 50% of octogenarians have difficulty communicating without the use of amplification, and in many, the cause is genetic. Inherited hearing impairment can occur with other co-inherited clinical features to form a recognized phenotype (syndromic hearing loss) or appear in isolation (non-syndromic hearing loss). Non-syndromic hearing loss accounts for approximately 70% of genetic deafness. It is almost exclusively monogenic and is highly heterogeneous, with some estimates of the number of deafness-causing genes exceeding 100. We are studying both syndromic and non-syndromic types of deafness. Projects include gene localization by linkage analysis and homozygosity mapping, mutation screening and detection, a variety of functional studies, and hearing-related research on mouse mutants targeting specific genes by RNAi. Membranoproliferative glomerulonephritis type 2 is also called Dense Deposit Disease (MPGN II/DDD). It causes chronic renal dysfunction that leads to kidney failure and a retinal disease similar to age-related macular degeneration, which is the most common cause of blindness in the elderly. Deficiency of and mutations in complement Factor H (CFH) are associated with development of MPGN II/DDD. Changes in CFH are also associated with another renal disease, atypical hemolytic uremic syndrome, and with age-related macular degeneration. We are studying relationships between the alternative pathway of the complement cascade, the structure of the glomerular basement membrane, and MPGN II/DDD to better understanding the pathophysiology of this disease.

    Faculty affiliations: 

    Jeff C Murray M.D.

    Current
    Jeff
    C
    Murray
    M.D.
    Professor
    Pediatrics
    Research area(s): 
    Developmental Genetics; Human Genetics
    Address
    2182
    ML
    2182
    ML
    Research
    Research Focus: 

    Advances in molecular biology, epidemiology, quantitative analysis and developmental biology have made it possible to identify genes involved in common complex traits in humans. Our laboratory applies these tools to study birth defects and prematurity. One project includes strategies to identify and characterize genes involved in cleft lip and palate, an inherited human birth defect. We have identified several genes involved in facial development and are studying their environmental covariates and clinical impact. For prematurity, a condition that causes 3 million deaths worldwide each year, we are using large sample collections and genome wide linkage and association to study thousands of individuals for millions of gene variants to generate enormous power for gene detection. Many of our studies are carried out using large population and epidemiologic studies of children , particularly from the Philippines, Japan, Denmark and Brazil, and we work in close collaboration with investigators in these countries. The studies of prematurity require clinical, biological and bioinformatic collaboration. We are also involved in studies of the prevention and better treatment of children with these disorders. Combining our molecular and developmental expertise with studies of epidemiology and environmental causes, holds out the promise for developing a better understanding of both rare disorders and common conditions. We are now developing strategies for prevention that include manipulation of genes or gene-environment interactions to prevent the primary occurrence of these tragic disorders. Graduate students serve in leadership roles for these projects and have primary responsibility for project design, implementation and publication. We are strongly committed to providing opportunities for students in the classroom, the laboratory and in fieldwork to develop their interests and expertise in the application of genetic tools to an understanding of human disease.

    Faculty affiliations: 

    Paul B McCray M.D.

    Current
    Paul
    B
    McCray
    M.D.
    Professor
    Pediatrics
    Research area(s): 
    Human Genetics; Molecular and Biochemical Genetics
    Address
    6320
    PBDB
    6320
    PBDB
    Research
    Research Focus: 

    Dr. McCray has a long-standing interest in the pathogenesis and treatment of cystic fibrosis. His laboratory has two main areas of investigation: 1) innate mucosal immunity in the lung and how this is altered in disease states, and 2) gene transfer for the treatment of inherited diseases.

    Studies of the anti-microbial properties of the airway surface liquid have stimulated interest in the anti-microbial proteins and peptides secreted by epithelia. Dr. McCray's lab is currently defining the tissue specific expression, regulation and anti-microbial activity of epithelial defensins and other proteins in model systems. These molecules may play a role in the innate mucosal immunity of the lung and other mucosal surfaces. A major effort is directed towards identifying novel host defense genes using genomics and large scale expression profiling.

    Another area of investigation is the development of integrating viral vectors for the treatment of inherited diseases. Current projects include gene transfer to airway epithelia for cystic fibrosis and gene transfer to the hepatocytes for the treatment of hemophilia A. The focus of these studies is on the development and optimization of retrovirus-derived vectors. A long-term goal is to develop strategies with integrating vector systems that could be successfully used to treat genetic diseases.

    Faculty affiliations: 

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