What is isovaleric acidemia?
Isovaleric acidemia (IVA)
is a type of organic acid disorder
in which affected individuals have problems breaking down an amino acid
from the food they eat.
Signs and symptoms may range from very mild to life-threatening. In severe cases, symptoms begin within a few days of birth and include poor feeding, vomiting, seizures, and lack of energy (lethargy); these may progress to more serious medical problems including seizures, coma, and possibly death.
In other cases, signs and symptoms appear during childhood and may come and go over time. A characteristic sign of IVA is a distinctive odor of sweaty feet during acute illness. Other features may include failure to thrive or delayed development.
IVA is caused by mutations
in the IVD
gene and is inherited in an autosomal recessive
Treatment involves moderate restriction of proteins in the diet and oral administration of glycine
which helps to rid the body of excess isovaleric acid.
Last updated: 3/30/2012
What are the signs and symptoms of isovaleric acidemia?
Health problems related to isovaleric acidemia range from very mild to life-threatening. In severe cases, the features of isovaleric acidemia become apparent within a few days after birth. The initial symptoms include poor feeding, vomiting, seizures, and lack of energy (lethargy). These symptoms sometimes progress to more serious medical problems, including seizures, coma, and possibly death. A characteristic sign of isovaleric acidemia is a distinctive odor of sweaty feet during acute illness. This odor is caused by the buildup of a compound called isovaleric acid in affected individuals.
In other cases, the signs and symptoms of isovaleric acidemia appear during childhood and may come and go over time. Children with this condition may fail to gain weight and grow at the expected rate (failure to thrive) and often have delayed development. In these children, episodes of more serious health problems can be triggered by prolonged periods without food (fasting), infections, or eating an increased amount of protein-rich foods.
Some people with gene mutations that cause isovaleric acidemia are asymptomatic, which means they never experience any signs or symptoms of the condition.
Last updated: 12/5/2011
What causes isovaleric acidemia?
Isovaleric acidemia is caused by mutations in the IVD
gene. The IVD
gene provides instructions for making an enzyme that plays an essential role in breaking down proteins from the diet. Specifically, this enzyme helps process the amino acid leucine, which is part of many proteins. If a mutation in the IVD
gene reduces or eliminates the activity of this enzyme, the body is unable to break down leucine properly. As a result, an organic acid called isovaleric acid and related compounds build up to harmful levels in the body. This buildup damages the brain and nervous system, causing serious health problems.
Last updated: 6/8/2011
How is isovaleric acidemia inherited?
Isovaleric acidemia is inherited in an autosomal recessive
pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
Last updated: 5/9/2011
How might isovaleric acidemia be treated?
There is currently no cure for isovaleric acidemia (IVA). Upon diagnosis, immediate treatment is typically necessary in order to prevent metabolic crises and complications that may follow. It is often recommended that affected individuals have a low-leucine / low-protein diet and use medical foods (such as special low-protein flours, pastas, and rice that are made especially for people with organic acid disorders) and leucine-free medical formula. A dietician with knowledge of IVA can help parents create a food plan that contains the right amount of protein, nutrients, and energy to keep the child healthy. Any diet changes should be under the guidance of a dietician. Medications that may be recommended include glycine
, which help rid the body of unwanted isovaleric acid and other harmful substances. No medication or supplement should be used without checking with a metabolic doctor. Children with symptoms of a metabolic crisis need medical treatment right away and may be given bicarbonate
, and other medications by IV.
With prompt and careful treatment, children with IVA have a good chance to live healthy lives with normal growth and development. However, some children, even when treated, may have repeated metabolic crises which can lead to life-long learning problems or mental retardation.
Last updated: 3/30/2012