|Other names||de Morsier syndrome|
|The optic nerve is underdeveloped in this condition|
Septo-optic dysplasia (SOD), known also as de Morsier syndrome, is a rare congenital malformation syndrome that features a combination of the underdevelopment of the optic nerve, pituitary gland dysfunction, and absence of the septum pellucidum (a midline part of the brain). Two or more of these features need to be present for a clinical diagnosis — only 30% of patients have all three. French-Swiss doctor Georges de Morsier first recognized the relation of a rudimentary or absent septum pellucidum with hypoplasia of the optic nerves and chiasm in 1956.
Signs and symptoms
The symptoms of SOD can be divided into those related to optic nerve underdevelopment, pituitary hormone abnormalities, or mid-line brain abnormalities. Symptoms may vary greatly in their severity.
Optic nerve underdevelopment
About one quarter of people with SOD have significant visual impairment in one or both eyes, as a result of optic nerve underdevelopment. There may also be nystagmus (involuntary eye movements, often side-to-side) or other eye abnormalities.
Pituitary hormone abnormalities
Mid-line brain abnormalities
SOD results from an abnormality in the development of the embryonic forebrain at 4-6 weeks of pregnancy. There is no known single cause of SOD, but it is thought that both genetic and environmental factors may be involved.
Rare familial recurrence has been reported, suggesting at least one genetic form (HESX1). In addition to HESX1, mutations in OTX2, SOX2 and PAX6 have been implicated in SOD. Genetic abnormalities are identified in fewer than one per cent of patients.
There have been suggestions that the use of drugs or alcohol during pregnancy may increase the risk of SOD.
A diagnosis of SOD is made when at least two of the following triad are present: optic nerve underdevelopment; pituitary hormone abnormalities; or mid-line brain abnormalities. Diagnosis is usually made at birth or during childhood, and a clinical diagnosis can be confirmed by MRI scans.
There is no cure for SOD. Pituitary insufficiency can be treated with hormones.
A European survey put the prevalence of SOD at somewhere in the region of 1.9 to 2.5 per 100,000 live births, with the United Kingdom having a particularly high rate and with increased risk for younger mothers.
In 1941 Dr David Reeves at the Children's Hospital Los Angeles described an association between underdevelopment of the optic nerve with an absent septum pellucidum. Fifteen years later French doctor Georges de Morsier reported his theory that the two abnormalities were connected and coined the term septo-optic dysplasia. In 1970 American doctor William Hoyt made the connection between the three features of SOD and named the syndrome after de Morsier.
In popular culture
Katie Price's son, Harvey has this condition 
- synd/2548 at Who Named It?
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