Whole genome sequencing (WGS) is a technique to determine every letter of DNA for an individual. The UK 100,000 Genomes Project (100K) performed WGS for NHS patients with rare diseases, including a group of genetic disorders called ciliopathies. Here, Best et al. analysed WGS data from ciliopathy patients in 100K using a reverse phenotyping strategy. This means they first looked for damaging DNA changes, then linked these findings to clinical data about the patients (their phenotype), to see if they could match and provide new genetic diagnoses. Through this approach, they improved diagnosis rates by 41%. (By Prof. Colin A. Johnson, https://jmg.bmj.com/content/early/2022/06/28/jmedgenet-2022-108476 )