Moreover, HMGA1 and HMGA2 represent valuable diagnostic markers as they are differently expressed depending upon the states of differentiation of TGCTs, with overexpression of HMGA1 in SEs, overexpression of both proteins in pluri-potential embryonal carcinoma cells, loss of expression of HMGA1 in YSTs and of both proteins in mature adult tissue teratoma areas [33–37]. This evidence concerns the gene HMGA1 and embryonal carcinoma.