OPA3

The OPA3 gene provides instructions for producing a protein that is located in the cell's energy-producing centers (the mitochondria). The function of this protein is currently unknown. Researchers believe that it may play a role in the self-destruction of cells (apoptosis).

3-methylglutaconic aciduria - caused by mutations in the OPA3 gene

At least two mutations in the OPA3 gene have been identified in people with 3-methylglutaconic aciduria type III, also called Costeff optic atrophy syndrome. One of these mutations prevents any OPA3 protein from being made. The other mutation deletes a segment of the OPA3 gene, which leads to the production of an abnormally short OPA3 protein with reduced function. A deficiency of normal OPA3 protein leads to the signs and symptoms of 3-methylglutaconic aciduria type III.

other disorders - caused by mutations in the OPA3 gene

Researchers have identified at least two mutations in the OPA3 gene that cause autosomal dominant optic atrophy and cataract (ADOAC). Autosomal dominant inheritance means that a mutation in one copy of the OPA3 gene in each cell is sufficient to cause this disorder. These mutations most likely impair the normal function of the OPA3 protein. The defective protein leads to optic atrophy, which causes the nerve that carries visual information from the eyes to the brain (the optic nerve) to shrink. People affected by this condition may also develop a clouding of the lens of the eye (cataract), which also affects vision.

Both of the reported mutations change one of the protein building blocks (amino acids) used to make the OPA3 protein. One mutation substitutes the amino acid serine for the amino acid glycine at protein position 93 (written as Gly93Ser or G93S). The other mutation substitutes the amino acid glutamic acid for the amino acid glutamine at protein position 105 (written as Gln105Glu or Q105E).