What are the genetic changes related to optic atrophy type 1 ?
Optic atrophy type 1 is caused by mutations in the OPA1 gene. The protein produced from this gene is made in many types of cells and tissues throughout the body. The OPA1 protein is found inside mitochondria, which are the energy-producing centers of cells. The OPA1 protein plays a key role in the organization of the shape and structure of the mitochondria and in the self-destruction of cells (apoptosis). The OPA1 protein is also involved in a process called oxidative phosphorylation, from which cells derive much of their energy. Additionally, the protein plays a role in the maintenance of the small amount of DNA within mitochondria, called mitochondrial DNA (mtDNA).  Mutations in the OPA1 gene lead to overall dysfunction of mitochondria. The structure of the mitochondria become disorganized and cells are more susceptible to self-destruction. OPA1 gene mutations lead to mitochondria with reduced energy-producing capabilities. The maintenance of mtDNA is also sometimes impaired, resulting in mtDNA mutations.  The vision problems experienced by people with optic atrophy type 1 are due to mitochondrial dysfunction, leading to the breakdown of structures that transmit visual information from the eyes to the brain. Affected individuals first experience a progressive loss of nerve cells within the retina, called retinal ganglion cells. The loss of these cells is followed by the degeneration (atrophy) of the optic nerve. The optic nerve is partly made up of specialized extensions of retinal ganglion cells called axons; when the retinal ganglion cells die, the optic nerve cannot transmit visual information to the brain normally.  It is unclear why the OPA1 gene mutations that cause optic atrophy type 1 only affect the eyes. Retinal ganglion cells have many mitochondria and especially high energy requirements, which researchers believe may make them particularly vulnerable to mitochondrial dysfunction and decreases in energy production.  Some individuals with optic atrophy type 1 do not have identified mutations in the OPA1 gene. In these cases, the cause of the condition is unknown.