Septo-Optic Dysplasia

What is septo-optic dysplasia?

Septo-optic dysplasia (also known as optic nerve hypoplasia) is a congenital disorder characterized by underdevelopment (hypoplasia) of the optic nerves. The optic nerves transmit impulses from the retina of the eye to the brain.

What are the symptoms of septo-optic dysplasia?

Although signs and symptoms vary, septo-optic dysplasia is traditionally defined by three characteristic features: 1) underdevelopment (hypoplasia) of the optic nerves, 2) abnormal formation of structures along the midline of the brain, and 3) pituitary hypoplasia.

Optic nerve hypoplasia is the underdevelopment of the optic nerves, which carry visual information from the eyes to the brain. In affected individuals, the optic nerves are abnormally small and make fewer connections than usual between the eyes and the brain. As a result, people with optic nerve hypoplasia have impaired vision in one or both eyes.
- Optic nerve hypoplasia can also be associated with unusual side-to-side eye movements (nystagmus) and other eye abnormalities.
Abnormal development of structures separating the right and left halves of the brain can lead to intellectual disability and other neurological problems
Pituitary hypoplasia; the pituitary is a gland at the base of the brain that produces several hormones. Underdevelopment of the pituitary can lead to a shortage (deficiency) of many essential hormones. Most commonly, pituitary hypoplasia causes growth hormone deficiency, which results in slow growth and unusually short stature.
- Severe cases cause panhypopituitarism, a condition in which the pituitary produces no hormones. Panhypopituitarism is associated with slow growth, low blood sugar (hypoglycemia), genital abnormalities, and problems with sexual development.

What causes septo-optic dysplasia?

Although the exact cause of septo-optic dysplasia is unknown, it is believed that both genetic and environmental factors play a role.

Viruses, medications, and blood flow disruption have all been suggested as possible environmental causes.
Thus far, three genes (HESX1, OTX2, and SOX2) have been associated with septo-optic dysplasia. Typically, people do not have a family history of septo-optic dysplasia, but there have been a few cases in which multiple family members have been diagnosed. Familial cases may follow an autosomal recessive or autosomal dominant pattern of inheritance.

How is septo-optic dysplasia diagnosed?

Septo-optic dysplasia is diagnosed by a complete ophthalmologic examination. Imaging studies such as magnetic resonance imaging (MRI) and computerized tomography (CT) are used to examine the corpus callosum and optic nerves. Abnormal levels of serum cortisol and growth hormone help to confirm the diagnosis.