Retinal Fundus

iGWAS uses self-supervised contrastive learning (SimCLR-style framework with a CNN encoder backbone) to extract a 128-dimensional phenotype vector directly from retinal fundus images without any manual labels. Trained on 40,000 EyePACS images via instance discrimination, then applied to 130,329 UK Biobank fundus images. GWAS on these 128 learned phenotypes identified 14 genome-wide significant loci. First demonstration of unsupervised deep phenotyping for image-based GWAS — discovering genetic associations without predefined human annotations.

self-supervised contrastive learning, SimCLR, CNN, retinal fundus, deep phenotyping, image-based GWAS, UK Biobank

Existing imaging genetics studies have been mostly limited in scope by using imaging-derived phenotypes defined by human experts. Here, leveraging new breakthroughs in self-supervised deep representation learning, we propose a new approach, image-based genome-wide association study (iGWAS), for identifying genetic factors associated with phenotypes discovered from medical images using contrastive learning. Using retinal fundus photos, our model extracts a 128-dimensional vector representing features of the retina as phenotypes. We identified 14 loci with genome-wide significance.

transferGWAS performs GWAS directly on full medical images using deep transfer learning: (1) a pretrained CNN (ResNet-based architecture, pretrained on ImageNet) extracts feature embeddings from raw images; (2) these learned representations are used as quantitative phenotypes for genetic association testing. Applied to UK Biobank retinal fundus images, identified 60 genomic regions including 7 novel candidate loci for eye-related traits. First demonstration of direct GWAS on whole images without predefined phenotype engineering.

deep transfer learning, pretrained CNN, ResNet, retinal fundus, whole-image GWAS, representation learning, UK Biobank

MOTIVATION: Medical images can provide rich information about diseases and their biology. However, investigating their association with genetic variation requires non-standard methods. We propose transferGWAS, a novel approach to perform genome-wide association studies directly on full medical images. First, we learn semantically meaningful representations of the images based on a transfer learning task, during which a deep neural network is trained on independent but similar data. Then, we perform genetic association tests with these representations. RESULTS: We validate the type I error rates and power of transferGWAS in simulation studies of synthetic images. Then we apply transferGWAS in a genome-wide association study of retinal fundus images from the UK Biobank. This first-of-a-kind GWAS of full imaging data yielded 60 genomic regions associated with retinal fundus images, of which 7 are novel candidate loci for eye-related traits and diseases.