Mitochondrial disorders are a genetically diverse group of individually rare, but severe human diseases for which no causal treatments are available so far. The GENOMIT consortium assembles the national networks from Germany, Italy, UK and Japan and the main centers for mitochondrial diseases in Austria and France, collectively following more than 6,000 patients. GENOMIT acts in close collaboration with the national patient organizations to improve diagnosis and care of mitochondrial disease patients. GENOMIT will i) further develop its global mitochondrial patient registry and establish disease- specific outcome measures and natural history data to prepare for clinical trials, ii) boost genome-wide diagnostics and optimize interpretation of genomic data by aggregating >3,000 exome and RNA sequencing datasets, iii) extend functional studies on novel variants, genes and pathways involved in the pathophysiology of mitochondrial diseases. GENOMIT partners are established national hubs for molecular diagnosis and state-of-the-art care for patients with mitochondrial disease. They leverage on national networks collaborating on a global registry and the largest collection of genomic data pertaining to mitochondrial disease world-wide. Each partner has also developed unique expertise that will be shared synergistically within the network. GENOMIT will thus create the critical mass to expand knowledge on the natural history, to identify novel mitochondrial disease genes, to gain insight into disease mechanisms and will be an invaluable resource for clinical trials.