However the BRCA1 murine model, BRCA1-I26A, in which BRCA1 interaction with E2 Ub conjugating enzymes is reduced, is viable and not tumor prone,61,62 and if the fidelity of HR promoted by other regions of BRCA1 remains high this may explain why tumor development is stymied. The gene discussed is BRCA1; the disease is neoplasm.