3-methylglutaconic aciduria type 1 (3MGA1) is a genetic disorder in which the body cannot get energy from a substance called leucine. Leucine is one of the amino acids, which are the building blocks of proteins in our bodies. Because people with 3MGA1 can’t break down leucine for energy to support muscle function and growth, they have a variety of symptoms that are present at birth. These symptoms may include developmental delays, seizures, muscle twitches (dystonia), and muscle weakness.
3MGA1 is caused by a mutation (change) to the AUH gene, which produces a protein to break down leucine. When there is a mutation to the AUH gene, this protein either isn’t produced or isn’t functional, so the body can’t get energy from leucine. Under normal conditions, the protein is present in the part of the cell that produces energy (the mitochondria), so 3MGA1 is a type of mitochondrial disease. 3MGA1 is also an organic acid condition because it causes harmful 3-methylglutaconic acid build up in the body.
3MGA1 is an autosomal recessive disease, meaning that an affected person has two mutated copies of the AUH gene. People with only one mutated copy of the gene are called carriers. Any child of two carriers has a one in four chance of having 3MGA1. To diagnose 3MGA, a doctor will test a urine sample because the level of organic acid is higher in 3MGA1 than any of the other types of 3MGA. Treatment options depend on the symptoms but may include lowering dietary leucine intake. Many babies are screened for 3MGA disorders at birth so that treatment can begin early, but the conditions included in newborn screening differ from state to state. For more information, visit Baby’s First Test. Talk with baby’s doctor about the most current treatment options. Genetic counselors and support groups are also a good source of information.