Background

Aberrant DNA methylation has been implicated in the etiology of multiple types of cancer, and has the poten-tial to be especially relevant in germ cell tumors (GCTs) due to extensive epigenetic reprogramming that occurs in the germ line and early embryo during normal development. Histologically, GCTs can be divided into germinomas and non-germinomas. Germinomas (GERs; also called seminomas in the testis and dysgerminomas in the ovary) are tumors of undifferentiated germ cells that retain markers of pluripotency. In contrast, non-germinomas undergo differentiation to resemble somatic-type tissues (teratomas) or extra-embryonic structures (yolk sac tumor (YST) and choriocarcinoma). Studies of testicular GCTs have suggested that global methylation patterns differentiate the main histologi