The novel RASGEF1A-RET fusion was detected in an ER−/PR−/HER2− breast cancer and results from an inversion event on chromosome 10 with breakpoints in RASGEF1A intron 1 and RET intron 9 that juxtaposes the 5′UTR of RASGEF1A upstream of the RET kinase domain. This evidence concerns the gene RET and breast cancer.