• Genetics
• rare disease,
• Syndrome
• diagnosis

The 100 000 Genomes Project is a unique, national programme combining research and transformation of clinical care, by undertaking whole genome sequencing (WGS) in patients with rare diseases and cancer. Made possible by technological advances in next-generation sequencing1 and falling costs, this project aims to find the genes which cause a patient's rare disease and identify genetic changes which occur in the tumour of a child or adult with cancer, to understand the mechanism of disease and develop therapies to personalise treatment. Patients are recruited through the National Health Service (NHS) and their medical course is tracked for life through their NHS number with results fed back through routine NHS services. It will also lay the foundations for a new ‘genomic medicine’ service for the NHS.2 The project is coordinated by Genomics England, with participants enrolled through one of 13 NHS Genomic Medicine Centres (figure 1), covering all of England. Unlike genome projects in other countries3 that have yielded information on variants associated with common diseases and ancestry, the scale of the 100 000 Genomes Project is much greater. The ability to track long-term outcomes through the patients' NHS number provides a unique opportunity to link genomic and phenotypic data to hospital admissions (via hospital episode statistics) as well as lifelong response to interventions and treatments.