Welcome to the Rare Classroom, a new series from Patient Worthy. Rare Classroom is designed for the curious reader who wants to get informed on some of the rarest, most mysterious diseases and conditions. There are thousands of rare diseases out there, but only a very small number of them have viable treatments and regularly make the news. This series is an opportunity to learn the basics about some of the diseases that almost no one hears much about or that we otherwise haven’t been able to report on very often.

Eyes front and ears open. Class is now in session.

The disease that we will be learning about today is:

Septo-Optic Dysplasia

Also known as de Morsier syndrome.

What is Septo-Optic Dysplasia?

• Septo-optic dysplasia is a rare congenital malformation which is characterized by a trio of complications, including absence or underdevelopment of midline of the brain, dysfunction of the pituitary gland, and underdeveloped optic nerve.
  • Only two of these features are required for a diagnosis, and only about 30% of patients actually present with all three of them
  • Diagnosis is usually made at birth or in early childhood
• Prevalence is estimated at 1.9 to 2.5 births per 100,000
  • The UK, however, seems to have a higher-than-average rate
• The alternate name, de Morsier syndrome, is named in recognition of Georges de Morsier, a French-Swiss physician that recognized the disorder for the first time in 1956.

How Do You Get It?

• Septo-optic dysplasia has been linked to an abnormality in the development of the embryo’s forebrain relatively early in its development, typically around 4-6 weeks.
• While there isn’t a single explanation for all cases, a combination of genetic and environmental factors likely contribute
• Risk factors include family history and young age of motherhood
  • A mutation impacting a gene called HESX1 has been identified in some familial cases
  • Other genes that have been linked to septo-optic dysplasia include OTX2, PAX6, and SOX2

What Are the Symptoms?

• Septo-optic dysplasia is defined by three principal features:
  • Midline brain abnormalities
    • Certain midline structures don’t develop normally, such as the septum pellucidum and corpus callosum. Symptoms include seizures, developmental delays, cortical dysplasia, spastic quadriplegia, schizencephaly, and polymicrogyria
  • Underdevelopment of the optic nerve
    • Vision impairment is present in around 25% of patients. Other symptoms include strabismus and nystagmus.
  • Abnormalities in pituitary hormones
    • The pituitary gland is underdeveloped, triggering growth hormone deficiency, hypopituitarism, and panhypopituitarism

How Is It Treated?

• No cure is available for septo-optic dysplasia
• Generally treatment is symptomatic and supportive, and a multidisciplinary care team is typically necessary for proper treatment of the disease
• Hormone replacement therapy is often used to address pituitary dysfunction, but vision problems are generally untreatable.

Where Can I Learn More???

• Check out our cornerstone on the disease here.
• Learn more about this illness from the MAGIC Foundation.