He is best known for his work on the clinico-pathological features of hereditary breast cancer and for his discovery and characterization of cancer predisposing founder mutations in Montreal populations, including a germline pathogenic missense variant in MSH2 in the Ashkenazim and disease-causing variants in PALB2 and RAD51D in French Canadians. In collaboration with Jacek Majewski, he identified biallelic variants in SMARCA4 as the sole cause of small cell carcinoma of the ovary, hypercalcemic type. He collaborates extensively with medical professionals and researchers around the world to better understand the genetics of various cancers. For the past 10 years, with nearly fifty publications his team extensively defined the phenotypes linked to the DICER1 pleiotropic tumor predisposition syndrome and is now exploring the functional impact of inherited mutations in DICER1. Another recent research focus involves genome-wide characterization of patients with multiples primary tumors to identify the genetic predisposing factors at work in these individuals.