Next generation sequencing is highly applicable to the diagnosis of Mendelian disorders as many are due to single gene mutations. KCCG developed the southern hemisphere’s first clinically accredited test using Whole Genome Sequencing to diagnose patients with Mendelian Disorders, now offered by Genome.One. Dr Lisa Ewans, with colleagues from KCCG is applying WGS to diagnose patients with Mendelian Disorders, particularly those that have not received a diagnosis from previous genetic testing. By looking beyond the protein coding genome, we aim to better understand the impact of genetic variation upon regulatory, and other high-impact elements in the genome like non-canonical splicing elements. We have developed ClinSV (CNV and SV detection, led by Dr André Minoche), mity (mtDNA characterisation, led by Ms Clare Puttick), ROHmer (ROH detection tool, led by Ms Clare Puttick), and Seave (variant annotation and interpretation, led by Dr Vel Gayevskiy) to facilitate this research. This work is in collaboration with many clinicians, including Dr Tracy Dudding-Byth, Dr Mike Field, Dr Rani Sachdev, Dr Elizabeth (Emma) Palmer.