A major problem in the care of patients with FA is managing the known risk of leukemia. As techniques for genetic analysis have exponentially improved in recent years, we now have the capability of finding very rare DNA mutations in the bone marrow suggestive of possible eventual development of leukemia. Finding such mutations often leads to the decision to recommend that FA patients undergo bone marrow transplantation, resulting in exposure to the short- and long-term side effects of transplant. This proposal aims to understand the consequences of mutations recurrently found in FA patient blood stem cells with the long-term goal of informing surveillance approaches and the decision to use bone marrow transplantation.