TFCP2L1 is not expressed in normal adult testes, though it is in intratubular germ cell neoplasia unclassified (ITGCN, formerly known as carcinoma in situ, CIS) [24], a non-invasive precursor lesion from which TGCT is widely accepted to originate. The gene discussed is TFCP2L1; the disease is testicular germ cell tumor.