Over the last few years, several scientific advances have contributed to the approval of breakthrough therapies for rare disease conditions. The better understanding of human genetics has helped pharmaceutical companies embrace gene therapy technology to develop tools which help repair genetic mutations and treat the underlying cause of the disease. Gene therapy by gene addition took decades to reach clinical trials, whereas gene therapy by genome editing does not. Gene editing merely requires certainty about the causative mutation and suddenly we move from proof of concept to trial within 3 years. Since their first application to eukaryotic cells in 2013, the proliferation and refinement in particular of tools based on CRISPR has prompted a landslide of therapy-development studies for rare diseases. An estimated thousands of orphan diseases can now be tackled with the required legislative, entrepreneurial and research initiatives. A new wave of treatments based on gene editing technology are expected to be made available over the next few years.