Forensic DNA Phenotyping: Improving the Prediction of Eye, Hair, and Skin Color through Quantitative Measurement

poster abstractWithout a match in the DNA database or a reference profile, current methods in forensic DNA profiling fail to give any leads to further criminal investigations. Forensic DNA Phenotyping bridges that gap in the investigation by providing ‘intelligence’ through the identification of externally visible characteristics of the unknown individual from their biological sample left at the crime scene. Recent work on eye and hair color prediction using a tool called ‘HIrisPlex’ has allowed accurate predictions of blue or brown eye color with a precision greater than 95%, and of hair color with a precision of approximately 75% for blond, brown, black and red categories. DNA phenotyping is a new and exciting area of DNA profiling, however there are areas that still require improvement. These include the prediction of intermediate eye colors such as green, or the mechanisms and/or genes involved in age-dependent hair color changes. At this time, categorical skin color prediction is still being developed and will soon be included in the HIrisPlex system, however it is not until the day that pigmentation measurements move toward a quantitative color scale that accuracy will be at a maximum. Our research hopes to target this area specifically. While the predication of categorical measurements is helpful, the term “light brown” is subjective and leads to the possibility of error in interpretation. In order to circumvent this interpretation issue, understanding quantitative color prediction is key. To achieve this, we are in the midst of a database collection of approximately 5000 individuals in which we will perform genome-wide association studies (GWAS) to locate additional eye, hair and skin color genes associated with a quantitative pigment scale phenotype. This database will help create a world-wide representative statistical panel from which quantitative predictive measures can be ascertained. Furthermore, in conjunction with computer programming techniques, it will allow the creation of a user-friendly software program that will enable the prediction of pigmentation-related externally visible characteristics such as eye, hair and skin color. This software has the capacity to be a revolutionary intelligence tool to aid law enforcement investigations by producing a color-print out biological mugshot

Pancreatic beta cell autophagy is impaired in type 1 diabetes

Aims/hypothesis Pancreatic beta cells are subjected to exogenous damaging factors such as proinflammatory cytokines or excess glucose that can cause accumulation of damage-inducing reactive oxygen species during the pathogenesis of diabetes. We and others have shown that beta cell autophagy can reduce reactive oxygen species to protect against apoptosis. While impaired islet autophagy has been demonstrated in human type 2 diabetes, it is unknown if islet autophagy is perturbed in the pathogenesis of type 1 diabetes. We hypothesised that beta cell autophagy is dysfunctional in type 1 diabetes, and that there is a progressive loss during early diabetes development. Methods Pancreases were collected from chloroquine-injected and non-injected non-obese diabetes-resistant (NOR) and non-obese diabetic (NOD) mice. Age- and BMI-matched pancreas tissue sections from human organ donors (N = 34) were obtained from the Network for Pancreatic Organ Donors with Diabetes (nPOD). Tissue sections were stained with antibodies against proinsulin or insulin (beta cell markers), microtubule-associated protein 1 light chain 3 A/B (LC3A/B; autophagosome marker), lysosomal-associated membrane protein 1 (LAMP1; lysosome marker) and p62 (autophagy adaptor). Images collected on a scanning laser confocal microscope were analysed with CellProfiler and ImageJ. Secondary lysosomes and telolysosomes were assessed in electron micrographs of human pancreatic tissue sections (n = 12), and energy dispersive x-ray analysis was performed to assess distribution of elements (n = 5). Results We observed increased autophagosome numbers in islets of diabetic NOD mice (p = 0.008) and increased p62 in islets of both non-diabetic and diabetic NOD mice (p < 0.001) vs NOR mice. There was also a reduction in LC3-LAMP1 colocalisation in islets of diabetic NOD mice compared with both non-diabetic NOD (p < 0.001) and NOR mice (p < 0.001). Chloroquine elicited accumulation of autophagosomes in the islets of NOR (p = 0.003) and non-diabetic NOD mice (p < 0.001), but not in islets of diabetic NOD mice; and stimulated accumulation of p62 in NOR (p < 0.001), but not in NOD mice. We observed reduced LC3-LAMP1 colocalisation (p < 0.001) in residual beta cells of human donors with type 1 diabetes vs non-diabetic participants. We also observed reduced colocalisation of proinsulin with LAMP1 in donors with type 1 diabetes (p < 0.001). Electron microscopy also revealed accumulation of telolysosomes with nitrogen-dense rings in beta cells of autoantibody-positive donors (p = 0.002). Conclusions/interpretation We provide evidence of islet macroautophagy/crinophagy impairment in human type 1 diabetes. We also document accumulation of telolysosomes with peripheral nitrogen in beta cells of autoantibody-positive donors, demonstrating altered lysosome content that may be associated with lysosome dysfunction before clinical hyperglycaemia. Similar macroautophagy impairments are present in the NOD mouse model of type 1 diabetes

Fluorescently conjugated annular fibrin clot for multiplexed real-time digestion analysis

Impaired fibrinolysis has long been considered as a risk factor for venous thromboembolism. Fibrin clots formed at physiological concentrations are promising substrates for monitoring fibrinolytic performance as they offer clot microstructures resembling in vivo. Here we introduce a fluorescently labeled fibrin clot lysis assay which leverages a unique annular clot geometry assayed using a microplate reader. A physiologically relevant fibrin clotting formulation was explored to achieve high assay sensitivity while minimizing labeling impact as fluorescence isothiocyanate (FITC)-fibrin(ogen) conjugations significantly affect both fibrin polymerization and fibrinolysis. Clot characteristics were examined using thromboelastography (TEG), turbidity, scanning electron microscopy, and confocal microscopy. Sample fibrinolytic activities at varying plasmin, plasminogen, and tissue plasminogen activator (tPA) concentrations were assessed in the present study and results were compared to an S2251 chromogenic assay. The optimized physiologically relevant clot substrate showed minimal reporter-conjugation impact with nearly physiological clot properties. The assay demonstrated good reproducibility, wide working range, kinetic read ability, low limit of detection, and the capability to distinguish fibrin binding-related lytic performance. In combination with its ease for multiplexing, it also has applications as a convenient platform for assessing patient fibrinolytic potential and screening thrombolytic drug activities in personalized medical applications

Global skin colour prediction from DNA

Human skin colour is highly heritable and externally visible with relevance in medical, forensic, and anthropological genetics. Although eye and hair colour can already be predicted with high accuracies from small sets of carefully selected DNA markers, knowledge about the genetic predictability of skin colour is limited. Here, we investigate the skin colour predictive value of 77 single-nucleotide polymorphisms (SNPs) from 37 genetic loci previously associated with human pigmentation using 2025 individuals from 31 global populations. We identified a minimal set of 36 highly informative skin colour predictive SNPs and developed a statistical prediction model capable of skin colour prediction on a global scale. Average cross-validated prediction accuracies expressed as area under the receiver-operating characteristic curve (AUC) ± standard deviation were 0.97 ± 0.02 for Light, 0.83 ± 0.11 for Dark, and 0.96 ± 0.03 for Dark-Black. When using a 5-category, this resulted in 0.74 ± 0.05 for Very Pale, 0.72 ± 0.03 for Pale, 0.73 ± 0.03 for Intermediate, 0.87±0.1 for Dark, and 0.97 ± 0.03 for Dark-Black. A comparative analysis in 194 independent samples from 17 populations demonstrated that our model outperformed a previously proposed 10-SNP-classifier approach with AUCs rising from 0.79 to 0.82 for White, comparable at the intermediate level of 0.63 and 0.62, respectively, and a large increase from 0.64 to 0.92 for Black. Overall, this study demonstrates that the chosen DNA markers and prediction model, particularly the 5-category level; allow skin colour predictions within and between continental regions for the first time, which will serve as a valuable resource for future applications in forensic and anthropologic genetics

Optimizing differential identifiability improves connectome predictive modeling of cognitive deficits from functional connectivity in Alzheimer's disease

Functional connectivity, as estimated using resting state functional MRI, has shown potential in bridging the gap between pathophysiology and cognition. However, clinical use of functional connectivity biomarkers is impeded by unreliable estimates of individual functional connectomes and lack of generalizability of models predicting cognitive outcomes from connectivity. To address these issues, we combine the frameworks of connectome predictive modeling and differential identifiability. Using the combined framework, we show that enhancing the individual fingerprint of resting state functional connectomes leads to robust identification of functional networks associated to cognitive outcomes and also improves prediction of cognitive outcomes from functional connectomes. Using a comprehensive spectrum of cognitive outcomes associated to Alzheimer's disease (AD), we identify and characterize functional networks associated to specific cognitive deficits exhibited in AD. This combined framework is an important step in making individual level predictions of cognition from resting state functional connectomes and in understanding the relationship between cognition and connectivity

Meta-analysis of genome-wide association studies identifies 8 novel loci involved in shape variation of human head hair

Shape variation of human head hair shows striking variation within and between human populations, while its genetic basis is far from being understood. We performed a series of genome-wide association studies (GWASs) and replication studies in a total of 28 964 subjects from 9 cohorts from multiple geographic origins. A meta-analysis of three European GWASs identified 8 novel loci (1p36.23

Elucidating the mechanisms or interactions involved in differing hair color follicles

Forensic DNA phenotyping is an up and coming area in forensic DNA analyses that enables the prediction of physical appearance of an individual from DNA left at a crime scene. At present, there has been substantial work performed in understanding what genes/markers are required to produce a reliable prediction of categorical eye and hair color from the DNA of an individual of interest. These pigmentation markers (variants from HERC2, OCA2, TYR, SLC24A4, SLC45A2, IRF4 to name a few) are at the core of several prediction systems for eye and hair color such as IrisPlex, HIrisPlex, and the Snipper 2.5 suite. The contribution of these markers towards prediction in most cases however, only factors in an independent effect and do not take into account potential interactions or epistasis in the production of the final phenotypic color. Epistasis is a phenomenon that occurs when a gene’s effect relies on the presence of ‘modifier genes’, and can display different effects (enhance/repress a particular color) in genotype combinations rather than individually. In an effort to detect such epistatic interactions and their influence on hair color prediction models, for this current study, 872 individuals were genotyped at 61 associative and predictive pigmentation markers from several diverse population subsets. Individuals were phenotypically evaluated for eye and hair color by three separate independent assessments. Several analyses were performed using statistical approaches such as multifactor dimensionality reduction (MDR) for example, in an effort to detect if there are any SNP- SNP epistatic interactions present that could potentially enhance eye and hair color prediction model performances. The ultimate goal of this study was to assess what SNP-SNP combinations amongst these known pigmentation genes should be included as an additional variable in future prediction models and how much they can potentially enhance overall pigmentation prediction model performance. The second part of the project involved the analyses of several differentially expressed candidate genes between different hair color follicles of the same individual using quantitative Real Time PCR. We looked at 26 different genes identified through a concurrent non-human primate study being performed in the laboratory. The purpose of this study was to gain more insight on the level of differentially expressed mRNA between different hair color follicles within the same human individual. Data generated from this part of the project will act as a pilot study or ‘proof of principle’ on the mRNA expression of several pigmentation associated genes on individual beard hair of varying phenotypic colors. This analysis gives a first glimpse at expression levels that remain constant or differentiate between hairs of the same individual, therefore limiting the contribution of individual variation

β-Cell Autophagy in the Pathogenesis of Type 1 Diabetes

Indiana University-Purdue University Indianapolis (IUPUI)Type 1 diabetes (T1D) is a multifactorial disease involving genetic and environmental factors. One of the factors implicated in disease pathogenesis is early life viral infection. A typical immune response to viral infection includes production of type 1 interferons (IFN), such as IFN-α, which can induce stress in the pancreatic β-cells. Reactive oxygen species (ROS) accumulation occurs after exposure to other inflammatory cytokines, causing oxidative stress that may be linked to T1D pathogenesis. Therefore, we hypothesized that IFN-α may also elicit β-cell ROS accumulation. Our in vivo and in vitro experiments with human islets showed rapid and heterogenous ROS accumulation with IFN-α. Although T1D is characterized by autoimmune destruction of β-cells, some cells survive this persistent attack. We hypothesized that survival/ death of β-cells could be attributed to the ability to effectively mitigate ROS accumulation. One mechanism to mitigate ROS is autophagy, which degrades and recycles cellular components to promote cellular homeostasis. We observed an impairment in autophagy in β-cells of donors with T1D as well as in islets of diabetic non-obese diabetic (NOD) mouse model of autoimmune diabetes. Autophagic flux was also impaired in diabetic NOD mouse islets, further confirming impairment of autophagy. Interestingly, we observed an induction of autophagy after acute treatment with IFN-α both in vitro and in vivo, suggesting compensatory upregulation of autophagy to restore homeostasis. Similarly, we observed an increase in autophagosomes and telolysosomes in β-cells of normoglycemic autoantibody positive organ donors compared to nondiabetic organ donors. Together, these data implicate a defect in the final degradation step of autophagy involving lysosomes. Therefore, we analyzed the activity and expression of lysosomal cysteine protease Cathepsin H (CTSH, a T1D susceptibility locus), and found both to be increased in islets of pre-diabetic NOD mice. Together, these data support compensatory hyperactivation of lysosomal enzymes prior to overt diabetes, potentially to rid the cell of ROS and degradation-resistant oxidized proteins and lipids. We also observed that C57Bl/6J mice lacking a key autophagy enzyme, ATG7, in their β-cells, spontaneously developed hyperglycemia. Collectively, these data highlight the importance of -phagic degradation process in the pathogenesis of T1D.2022-12-2