Developing strategies to functionally annotate and precisely target genetic variants

Genome sequencing has identified recurrently mutated genes driving cancer, yet our interpretation of individual variants remains limited. Moreover, we lack targeted therapies for most cancer-driving mutations. Here, we annotate genetic variants at scale and develop molecular tools for variant targeting. Using pooled functional screens, we profiled nearly all protein-coding variants in the tumour-suppressor gene SMAD4. This revealed both known and novel loss- and gain-of-function mutations that can be used to inform clinical diagnoses. In parallel, we optimised CRISPR-Cas13 for targeted RNA knockdown in human cells, identifying DUSP11 as a key regulator of activity and enhancing Cas13-based RNA targeting approaches.