Isobutyryl-coenzyme A dehydrogenase deficiency
Encyclopedia
Isobutyryl-coenzyme A dehydrogenase deficiency, commonly known as IBD deficiency, is a rare metabolic disorder in which the body is unable to process certain amino acid
s properly.
People with this disorder have inadequate levels of an enzyme that helps break down the amino acid valine
, resulting in a build up of valine in the urine, a symptom called valinuria.
), seizures, and low numbers of red blood cells (anemia
). Another feature of this disorder may be very low blood levels of carnitine
(a natural substance that helps convert certain foods into energy).
Isobutyryl-CoA dehydrogenase deficiency may be worsened by long periods without food (fasting) or infections that increase the body's demand for energy. Some individuals with gene mutations that can cause isobutyryl-CoA dehydrogenase deficiency may never experience any signs and symptoms of the disorder.
Defects in the ACAD8
gene cause isobutyryl-coenzyme A dehydrogenase deficiency. The ACAD8 gene provides instructions for making an enzyme that plays an essential role in breaking down proteins from the diet. Specifically, the enzyme is responsible for processing valine, an amino acid that is part of many proteins. If a mutation in the ACAD8 gene reduces or eliminates the activity of this enzyme, the body is unable to break down valine properly. As a result, poor growth and reduced energy production may occur.
This disorder is inherited in an autosomal recessive pattern, which means the defective gene is located on an autosome
, and two copies of the gene - one from each parent - are needed to be born with the disorder. The parents of an individual with an autosomal recessive disorder are carriers of one copy of the defective gene, but do not show signs and symptoms of the disorder.
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s properly.
People with this disorder have inadequate levels of an enzyme that helps break down the amino acid valine
Valine
Valine is an α-amino acid with the chemical formula HO2CCHCH2. L-Valine is one of 20 proteinogenic amino acids. Its codons are GUU, GUC, GUA, and GUG. This essential amino acid is classified as nonpolar...
, resulting in a build up of valine in the urine, a symptom called valinuria.
Diagnosis
Babies with this disorder are usually healthy at birth. The signs and symptoms may not appear until later in infancy or childhood and can include poor feeding and growth (failure to thrive), a weakened and enlarged heart (dilated cardiomyopathyDilated cardiomyopathy
Dilated cardiomyopathy or DCM is a condition in which the heart becomes weakened and enlarged and cannot pump blood efficiently. The decreased heart function can affect the lungs, liver, and other body systems....
), seizures, and low numbers of red blood cells (anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
). Another feature of this disorder may be very low blood levels of carnitine
Carnitine
Carnitine is a quaternary ammonium compound biosynthesized from the amino acids lysine and methionine. In living cells, it is required for the transport of fatty acids from the cytosol into the mitochondria during the breakdown of lipids for the generation of metabolic energy. It is widely...
(a natural substance that helps convert certain foods into energy).
Isobutyryl-CoA dehydrogenase deficiency may be worsened by long periods without food (fasting) or infections that increase the body's demand for energy. Some individuals with gene mutations that can cause isobutyryl-CoA dehydrogenase deficiency may never experience any signs and symptoms of the disorder.
Genetics
ACAD8
Isobutyryl-CoA dehydrogenase, mitochondrial is an enzyme that in humans is encoded by the ACAD8 gene.-Further reading:...
gene cause isobutyryl-coenzyme A dehydrogenase deficiency. The ACAD8 gene provides instructions for making an enzyme that plays an essential role in breaking down proteins from the diet. Specifically, the enzyme is responsible for processing valine, an amino acid that is part of many proteins. If a mutation in the ACAD8 gene reduces or eliminates the activity of this enzyme, the body is unable to break down valine properly. As a result, poor growth and reduced energy production may occur.
This disorder is inherited in an autosomal recessive pattern, which means the defective gene is located on an autosome
Autosome
An autosome is a chromosome that is not a sex chromosome, or allosome; that is to say, there is an equal number of copies of the chromosome in males and females. For example, in humans, there are 22 pairs of autosomes. In addition to autosomes, there are sex chromosomes, to be specific: X and Y...
, and two copies of the gene - one from each parent - are needed to be born with the disorder. The parents of an individual with an autosomal recessive disorder are carriers of one copy of the defective gene, but do not show signs and symptoms of the disorder.