In 1996, Dr. Brenda Gallie identified the cause of drug-resistant childhood cancer of the retina, leading to an effective chemotherapy modification.

Gallie determined that somatic inactivation of the RB1 gene initiated retinoblastoma tumors, pointing to the role of tumor suppressor genes in cancer. If the first mutant RB1 allele (M1) arises in the germline, it predisposes to bilateral retinoblastoma and multiple other cancers, when the second allele (M2) undergoes somatic inactivation in embryonic retina and other tissues.

Today, Gallie is Professor in Medical Biophysics, Molecular Genetics, and Ophthalmology. She directs the Retinoblastoma Program at the Hospital for Sick Children. She received The Order of Ontario and Membership, Order of Canada for delivering personalized medicine and predictive genomic studies to families.