A congenital optic nerve disease that resembles normal tension glaucoma (NTG)
Cavitary optic disc anomaly (CODA) is a congenital disease in which the optic nerve is deeply excavated at birth much like cupping that occurs in severe cases of glaucoma.
In rare cases many members of a family have CODA and the disease is passed down from generation to generation as a dominant trait as a shown in the pedigree below.
This is a pedigree or family tree of a family affected with CODA. The squares represent male family members while the circles represent females. The family members with black symbols have CODA while those with white symbols don’t have CODA. It is unknown whether those with grey symbols have CODA.
We have collected DNA samples from those with CODA in the family above. Using a research technique called linkage analysis, we compared the inheritance of genetic markers in the family with the transmission of CODA from generation to generation in the family. With these investigations we were able to show that the gene that causes CODA is located within a segment of chromosome 12 – a region that corresponds to less than 0.5% of the genome.
Currently, we are systematically testing each of the genes in the segment of chromosome 12 to find the one that is responsible for causing CODA. Discovery of the gene that causes CODA will help researchers to better understand the disease and may lead to the development of better treatments.
Patients that have CODA develop abnormal optic nerves in the absence of high pressure in the eyes, much like the damage that occurs in normal tension glaucoma. Consequently, it is likely that discovery of the gene that causes CODA may also provide some insights into the causes of normal tension glaucoma.