PROJECT SUMMARY
The overall objective of this proposal is to develop and validate a deep learning analytical framework to integrate
histological traits into systems genetics analysis of complex diseases. Mapping the risk genes for poor health
outcomes is a major focus of biomedical research, and new approaches to improve genetic mapping power can
have a transformative impact on public health. Genetic disease risk manifests through complex interactions
between gene regulation and tissue structure, ultimately influencing organ function. However, quantifying tissue
structure for quantitative genetic mapping has not been widely adopted. This is partly because histological
scoring has traditionally been labor intensive and error prone, and limited to coarse measures (e.g., discrete
categories) that are suboptimal for association testing. In contrast, deep neural networks (DNNs) now routinely
automate laborious image quantification tasks for histopathology, making them an ideal platform for integrating
histology into genetic analysis. Furthermore, unlike human-defined histological scores, DNN readouts enable
objective histological trait discovery as a function of genetic, molecular, and physiological variation. In this
project, histological features will be rigorously and robustly quantified using DNNs and these data will be
integrated into novel multiscale statistical models that will connect genetic, molecular, and histological variation
to physiological outcomes. In particular, novel methods will be developed to integrate histology into three major
classes of systems genetic analysis, i.e., heritable trait inference, causal mediation analysis, and molecular
quantitative trait locus (mQTL) mapping. These methods will be developed and validated using a data set of
genetic, histological, transcriptomic, proteomic, and physiological data from a cohort of Diversity Outbred mice
used for the study of age-related kidney disease. By using a model system, complex genetic effects and causal
mediation hypotheses can be directly tested to validate and refine the analytical framework. The specific aims of
this proposal include: Aim 1: Identify maximally heritable histological traits through deep learning on paired
genotypes and histological images. Aim 2: Genetically map histological mediators of complex physiological traits
using deep learning on histological images. Aim 3: Identify causal paths connecting molecular QTLs (mQTLs) to
outcomes through histological mediators. The outcome of this study will be a validated methodological framework
for histological systems genetics that is modular, enabling a wide range of users to incorporate appropriate
computer vision tools into state-of-the-art systems genetics workflows for any complex disease.