ISG15 and Alzheimer disease: MSMD is caused by germline mutations affecting 16 different genes i.e., 14 autosomal genes [AD or AR inheritance: IFNGR1 (181) and IRF8 (182); AR inheritance: IFNGR2 (183), IL12B (184), IL12RB1 (185), ISG15 (186), TYK2 (187), SPPL2A (188), IL12RB2 (189, 190), IL23R (189, 190), RORC (191), JAK1 (180), IFNG (192); AD inheritance STAT1 (193)] and two X-linked gene [NEMO (194) and CYBB (195)].