What is the difference between Septo-Optic Dysplasia and Holoprosencephaly?
Septo-optic dysplasia (SOD) or DeMorsier Syndrome consisists of small optic nerves, absence of the septum pellucidum, and various other midline brain problems (such as pituitary or hypothalamic abnormalities). Most children are missing part or all of the corpus callosum. While there may be some overlapping features with holoprosencephaly (HPE), in SOD there is no problem with the lack of cleavage of the cerebral hemispheres or the deeper structures. Some children with HPE have the equivalent of SOD with some additional features. By “labelling” a child with HPE rather than SOD, physicians are referring to a more extensive brain involvement with lack of cleavage between the two cerebral hemispheres and the midline structures that is seen in HPE. In both disorders children may have problems with regulation of sodium and water (diabetes insipidus). The disorders are thought to have different causes and onset during fetal life.
