Autosomal dominant optic atrophy and cataract is one form of autosomal dominant optic atrophy, a group of conditions that are estimated to affect 1 in 30,000 people worldwide, and approximately 1 in 10,000 people in Denmark. A form of optic atrophy called optic atrophy type 1 accounts for most cases, while autosomal dominant optic atrophy and cataract is thought to represent only a few percent of autosomal dominant optic atrophy cases.

Autosomal dominant optic atrophy and cataract is caused by mutations in a gene called OPA3. The protein produced from this gene is made in cells and tissues throughout the body. The OPA3 protein is found within mitochondria, which are the energy-producing centers of cells. While the exact function of the protein is unknown, it is thought to play a role in the organization of the shape and structure of the mitochondria and in controlled cell death (apoptosis).

Mutations in the OPA3 gene lead to abnormal mitochondrial function. The mitochondria become misshapen and disorganized and have reduced energy-producing capabilities. Cells that contain these poorly functioning mitochondria seem to be more susceptible to apoptosis. In particular, affected cells that have high energy demands, such as retinal ganglion cells, are likely to die prematurely. Specialized extensions of retinal ganglion cells, called axons, form the optic nerves, so when retinal ganglion cells die, the optic nerves atrophy and cannot transmit visual information to the brain. Together, these effects reduce vision in affected individuals. It is likely that nerve cells in other parts of the body are similarly affected by dysfunctional mitochondria, resulting in the signs and symptoms of neuropathy in individuals with autosomal dominant optic atrophy and cataract. It is unclear how OPA3 gene mutations lead to cataracts and other eye problems that can occur in autosomal dominant optic atrophy and cataracts.