In addition to established recurrent copy number alterations (CNAs), including chromosome arm-level gains spanning KRAS (12p), amplifications involving KIT (4q12; 19% cases) and MDS2 (1p36.32; 17% cases), and deletions spanning DMRT1 (9p24.3; 37% cases), which is associated with testicular germ cell tumour susceptibility25, we identified 26 additional novel events. Here, MDS2 is linked to childhood testicular germ cell tumor.