Section 11-C(3): Normal tension glaucoma

Most cases of normal tension glaucoma (NTG) are sporadic with no clear family history. However, rare cases of families with many affected members have been reported. In these families, NTG is inherited as an autosomal dominant trait. Genetic studies have shown that mutations in a gene known as optineurin (OPTN) are responsible for a significant fraction of familial NTG cases. A single optineurin mutation has been associated with glaucoma in several large NTG families. The role of the optineurin gene in sporadic cases of NTG has not been clearly defined.

More is known about the optineurin gene than the myocilin gene. The optineurin gene produces a protein that appears to have many functions. Some studies suggest that optineurin is involved in apoptosis, which is a process by which cells self-destruct or “commit suicide”. It is possible that the optineurin gene may cause optic nerve damage and glaucoma by promoting apoptosis of this tissue. Current studies are exploring the precise mechanism by which defects in the optineurin gene lead to glaucoma.

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