Final answer:
Septo-optic dysplasia (SOD) is related to the underdevelopment of the optic nerve and pituitary gland, and the absence of the brain's septum pellucidum, often involving mutations in the HESX1 gene.
Step-by-step explanation:
Septo-optic dysplasia (SOD), also known as de Morsier syndrome, is a disorder characterized by the underdevelopment of the optic nerve, pituitary gland dysfunction, and absence of the septum pellucidum (a membrane in the brain). The reference to the HEX1 gene may be a typo or a misunderstanding, as research suggests that mutations in the HESX1 gene are associated with some cases of septo-optic dysplasia. This condition can lead to vision problems, hormonal deficiencies, and learning difficulties. Diagnosis often involves magnetic resonance imaging (MRI), hormonal studies, and eye examinations.