The clinical and endocrinological findings in 24 children with septo-optic dysplasia and/or agenesis of the corpus callosum are described with reference to posterior pituitary function in a report from the Institute of Child Health and The Hospital for Sick Children, London, UK. Congenital optic nerve hypoplasia, absent septum pellucidum, and pituitary deficiency, characteristic of the complete syndrome of septo-optic dysplasia, were present in 8 children, and 13 had incomplete forms. Five had agenesis of the corpus callosum. Growth hormone insufficiency was found in 20 (83%). Nine (38%) had diabetes insipidus, often complicated by hypernatremia. Management of fluid balance was difficult, even with vasopressin treatments, because of blindness, developmental delay, impairment of the sense of thirst, and dependence on the parents for food and water intake. 
COMMENT. The syndrome of septo-optic dysplasia appears to be a mild form of holoprosencephaly with single cerebral ventricle and agenesis of the corpus callosum, among other midline defects. Anterior pituitary deficiency is a frequent feature of the syndrome, whereas posterior pituitary disorders are less well documented. In the present study, diabetes insipidus is shown to be a relatively common complication.