In this multicenter series, information about mutations that might predict response to IST such as BCOR was not consistently available, but the presence of a paroxysmal nocturnal hemoglobinuria (PNH) clone or HLA DR15 status, which had been found to be of value in predicting response in smaller (mostly single-center) series, did not predict IST response. The gene discussed is BCOR; the disease is paroxysmal nocturnal hemoglobinuria.