Causes of death in 12 patients with MBL levels < 1000 ng/mL , were: 6 patients died due to an infection (2 pulmonary aspergillosis,  2 Pseudomonas aeruginosa bacteremia, 1 Klebsiella pneumoniae bacteremia and 1 Pneumocystis jiroveci pneumonia), 2 patients because of graft versus host disease (GVHD), 2 patients due to a progression of the disease and 1 patient died due to a hemorrhage. The gene discussed is MBL2; the disease is graft versus host disease.