Summary
Genome sequencing has led to rapid advances in the diagnosis of pediatric rare diseases, but current
approaches fail to diagnose 60-70% of all cases. Efforts toward the interpretation of disease variants has
tended to focus on a relatively small set of rare or de novo coding variants implicated in Mendelian rare
disease; in this proposal, we outline approaches to substantially expand variant interpretation methods beyond
the exome and encompassing complex, non-Mendelian disease processes. We have previously provided
integrated functional genomic resources and computational tools to connect variants to rare disease
phenotypes. Our large-scale i2QTL induced Pluripotent Stem Cell (iPSC) resource provides a map of
developmental gene regulation across 1,490 cell lines, uncovering differential isoform expression, novel
splicing and regulatory effects in known rare disease genes, including in those not expressed in somatic
tissues. Furthermore, we recently released the IOGC model for connecting rare variants to function through
genomewide assays of multiple molecular phenotypes, providing a systematic method to uncover large-effect
rare variants in both coding and non-coding regions. Integrated with population-scale disease biobanks, we
have shown how these variants provide a powerful system to map the combined downstream consequences
on both cis- and trans-regulatory networks, identifying dysregulated core disease gene modules associated
with extreme effects on disease risk. In this proposal, we will conduct a comprehensive genomic and functional
assessment of pediatric patients from across the Midwest enrolled in the Genomic Answers for Kids (GA4K)
initiative at Children’s Mercy Hospital who have a suspected rare disease not explained by exome sequencing
(N=1,860). We have already embarked on generating functional profiles across disease tissues and patient-
derived iPSCs using multiple molecular assays, currently consisting of WGS (N=1,860), PacBio Long-Read
HiFi WGS (N=384), single-cell ATAC-seq (N=433) and single-cell RNA-seq (N=528). These assays will allow
us to systematically evaluate their use in identifying rare variants associated with downstream molecular
dysregulation in rare disease. We will then develop new statistical approaches integrating our pediatric rare
disease variant-to-function maps to uncover causal diagnostic variation explaining complex rare disease
phenotypes. This proposal builds on the PI’s previous contributions in integrated functional genomics research
within the NIH Undiagnosed Diseases Network and GTEx consortiums. Now, within the diverse, large-scale
GA4K initiative, the PI is leading efforts to catalyze next-generation diagnostics in pediatric rare disease
genomics in collaboration with research and clinical teams. Overall, we expect our research program will lead
to the improved diagnosis of pediatric rare diseases through the precise identification of underlying causal
genetic disease processes.