After the first few years of life, most teratomas are gonadal. Familial benign cystic teratoma of the ovary has been described in three generations of a family (Brenner and Wallach 1983). Adult testicular gonadal germ cell Tumours tend to be aneuploid, although infantile gonadal germ cell Tumours may more often be tetraploid or diploid, which suggests that they may have a different etiology (Silver et al. 1994). In fact, most teratomas develop in the sacrococcygeal area and tend to be benign. There may be associated malformations of the sacrum, vertebrae, and gastrointestinal or urogenital tracts. Familial teratoma with an autosomal dominant mode of inheritance has been described, with variable penetrance, and some affected individuals have been described to have anterior sacral meningocoele, sacral defects, or skin dimples without teratoma (Yates et al. 1983). The Currarino triad involves the association of partial sacral agenesis with intact first sacral vertebra (“sickle-shaped sacrum”), a presacral mass, and anorectal malformation. Some cases of the Currarino syndrome may be caused by mutations in the HLXB9 homeobox gene (Kim et al. 2007).