3-methylglutaconic aciduria, type III

Everyone has spelling differences in their genes. That's what makes us all different! A "variant" is a genetic spelling difference that has never been seen before or is not understood very well. If you have inherited a "variant" in OPA3, it means that there is a difference in how your OPA3 gene is spelled, but that we don't yet know if this difference makes the gene work less or if it is just the way your OPA3 gene is normally spelled.

Since the 3-methylglutaconic aciduria type 3 is caused by spelling changes in both of a person's OPA3 genes, it is possible to see someone who has one variant and one known mutation, or even someone with 2 variants. If this person is having symptoms of 3-methylglutaconic aciduria type 3, it more likely that the variants are spelling differences that make the gene work less. If they are not having symptoms, it makes it more likely that this is just a normal spelling difference.

If you already have a child with 3-methylglutaconic aciduria type 3, this means that both parents are "carriers" for a change in OPA3. A "carrier" is someone who has a change in 1 of the 2 copies of OPA3. Since they still have 1 working copy, they don't have the disease but they can pass on the genetic change to their child. The chance of 2 carriers having a child with 3-methylglutaconic aciduria type 3 is 1 in 4, or 25%. There is a 1 in 2, or 50%, chance that their child will be a carrier like them. Finally, there is a 1 in 4, or 25%, chance that the child will have both working copies of OPA3.