3-Methylglutaconic aciduria type 3
Type of disease: Rare conditions
Costeff syndrome is a rare genetic disorder more common in the Iraqi-Jewish population. It is caused by a mutation (change) in the OPA3 gene. This gene makes OPA3 protein, which may help shape the mitochondria (small parts of each cell that make energy). When the mitochondria are oddly shaped, they can’t make enough energy. The optic nerve (involved in vision) and movement center of the brain are affected the most. Vision loss begins in infancy or early childhood and gets worse over time (progressive). The child may also have involuntary eye movements and their eyes may not look in the same direction. Movement symptoms begin in late childhood and include stiffening muscles, jerky movements and decreased ability to coordinate muscle movement. Some children have mild to moderate intellectual delays. Progression seems to stop in early adulthood. The effect on life expectancy is unknown.
Costeff is both a mitochondrial and organic acid disorder because the oddly shaped mitochondria can’t break down organic acids well. Organic acids (such as 3MGA) are made as our body breaks down extra protein. Although Costeff is grouped with other 3MGA disorders, the level of acid build up is not enough to cause the severe symptoms seen in the other 3MGA disorders. Costeff is an autosomal recessive disorder, meaning both copies of OPA3 must be mutated.
A diagnosis of Costeff is confirmed by genetic testing. Although there is currently no cure, there are resources to help manage the disorder. Many babies are screened for 3MGA disorders at birth, but the disorders included in newborn screening vary from state to state. For more information, visit Baby’s First Test. Research is ongoing so talk with your child’s doctor about current treatment options. Genetic counselors and support groups are also good sources of information.