This project will be validating a test, called EpiSign, a proprietary machine learning algorithm built on rare genetic disease datasets (EpiSign Knowledge Database) which analyzes data obtained from wholegenome methylation arrays. This approach is expected to increase diagnostic yield above that of current genetic analyses. This project will validate the conditions for maximizing patient and health system impact and assess the evidence for first-visit and reflex scenarios for adoption of genome-wide DNA methylation testing within Canada. Future clinical adaption would see EpiSign implemented as a bioinformatics service with tertiary genetic centres engaging with their patients and performing the wet lab methylation array data production locally. These centres would then utilize a secure web-based portal to have their data interpreted by the EpiSign Knowledge Database. Expected benefits to Canada include improved quality of life to patients and families who will receive a long-awaited definitive diagnosis. Providing patients with a diagnosis sooner will also have cost benefits, as many tests will be avoided in addition to reducing the reliance on out-of-country commercial laboratories.