Browsing by Subject "Pigment"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Enhancing Our Genetic Knowledge of Human Iris Pigmentation and Facial Morphology
    (2019-12) Eller, Ryan; Walsh, Susan; Berbari, Nicolas; Lapish, Christopher; Picard, Christine; Roper, Randall
    The biological underpinnings that control iris pigmentation and facial morphology are two areas of research that over the last decade are becoming more thoroughly investigated due to the increased affordability of genotyping and advances in technology allowing for more advanced analysis techniques. Despite the ease of access to the data and the tools required to perform iris pigmentation and facial morphological studies, there are still numerous challenges researchers must overcome when exploring the genetics of these complex phenotypes. Some of these challenges include difficulty in working with the bioinformatic programs designed to analyze genetic associations, the inability to define a phenotype that captures the true nature of these traits, and analysis techniques that fail to model complex gene-gene interactions and their effect on a phenotype or phenotypes of interest. In this body of work, I attempted to address these challenges by designing a bioinformatic pipeline, Odyssey, that bridges the communication gaps between various data preparation programs and the programs that analyze genomic data. With this program, genome-wide association studies (GWAS) could be conducted in a quicker, more efficient, and easier manner. I also redefined iris color as a quantitative measurement of pre-defined color classes. In this way it is possible to define and quantify the unique and intricate mixtures of color, which allows for the identification of known and novel variants that affect individual iris color. I also improved upon current prediction models by developing a neural network model capable of predicting a quantitative output to four pre-defined classes; blue/grey, light brown (hazel), perceived green, and dark brown. I examined the effects of defining a simple facial morphology phenotype that more accurately captures the lower face and jaw shape. I then analyzed this phenotype via a GWAS and found several novel variants that may be associated with a square and diamond shaped face. Lastly, I demonstrated that structural equation modeling can be used in combination with traditional GWAS to examine interactions amongst associated variants, which unearths potential biological relationships that impact the multifaceted phenotype of facial morphology.
  • Thumbnail Image
    Item
    Staining and Identification of Pigments and Minerals in Tissue
    (2010) Wood, Debra M.
    A variety of pigments and minerals occur in the body naturally or when pathologic conditions present. Proper classification, identification, and demonstration of common pigments and minerals encountered in the histology laboratory are necessary to achieve the correct diagnosis and to assure the highest quality patient care. Classification and staining methods for artifact pigment, endogenous hematogenous & non-hematogenous, exogenous pigments and minerals will be discussed. The attendee will gain tips and troubleshooting techniques for the prevention and/or removal of artifact pigments as well as staining procedures for the demonstration of: • ferric & ferrous iron • bile • lipofuscins • melanin • asbestos • calcium • urates • copper The focus will be on the identification of common problems, how to avoid, recognize and correct them efficiently and accurately without risk of wasting patient sample. Knowledge of the basic fundamentals of general staining techniques and tissue identification is recommended but not required.