Our study also included cases of HO following astrocytoma, the most frequent cerebral tumor in the pediatric age, occurring in subjects with septo-optic dysplasia, a rare condition defined by variable combination of dysgenesis of midline brain structures including optic nerve hypoplasia and hypothalamic-pituitary dysfunction often associated with a wide variety of cerebral malformations of cortical development, and a child with causative mutation in the LHX3 gene. The gene discussed is LHX3; the disease is neoplasm of cerebral hemisphere.