The last decade has seen astonishing advances in understanding the genetic causes of rare diseases. Many novel monogenic disease genes have been discovered and whole exome/genome sequencing (WES/WGS) is now becoming available across many health services, including the UK NHS Genomic Medicine Service (GMS).
However, more than half of rare disease patients remain undiagnosed even after WGS, and the vast majority of their genomic data remains unexplored. Failures in functional genome annotation are preventing robust variant classification, exploration of the non-coding genome, and discovery of new disease-causing loci, resulting in apparently gene-elusive rare diseases. Moreover, most monogenic disease mechanisms remain poorly understood, inhibiting the development of novel therapies.