A broad classification for

genetic disorders A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorders ...

that result from an inability of the body to produce or utilize one enzyme that is required to oxidize fatty acids. The

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

can be missing or improperly constructed, resulting in it not working. This leaves the body unable to produce energy within the liver and muscles from fatty acid sources. The body's primary source of energy is glucose; however, when all the glucose in the body has been expended, a normal body digests fats. Individuals with a fatty-acid metabolism disorder are unable to metabolize this fat source for energy, halting bodily processes. Most individuals with a fatty-acid metabolism disorder are able to live a normal active life with simple adjustments to diet and medications. If left undiagnosed many complications can arise. When in need of glucose the body of a person with a fatty-acid metabolism disorder will still send fats to the liver. The fats are broken down to fatty acids. The fatty acids are then transported to the target cells but are unable to be broken down, resulting in a build-up of fatty acids in the liver and other internal organs. Fatty-acid metabolism disorders are sometimes classified with the lipid metabolism disorders, but in other contexts they are considered a distinct category.

Types

Incomplete list of various fatty-acid metabolism disorders. * Carnitine Transport Defect *

Carnitine-acylcarnitine translocase deficiency Carnitine-acylcarnitine translocase deficiency is a rare, autosomal recessive metabolic disorder that prevents the body from converting long-chain fatty acids into energy, particularly during periods without food. Carnitine, a natural substance ...

(CACT) * Carnitine Palmitoyl Transferase I & II ( CPT I deficiency & CPT II deficiency) * 2,4 Dienoyl-CoA Reductase Deficiency * Electron Transfer Flavoprotein (ETF) Dehydrogenase Deficiency ( GAII & MADD) * 3-Hydroxy-3-methylglutaryl-CoA lyase deficiency (HMG deficiency) *

Very long-chain acyl-coenzyme A dehydrogenase deficiency Very long-chain acyl-coenzyme A dehydrogenase deficiency is a fatty-acid metabolism disorder which prevents the body from converting certain fats to energy, particularly during periods without food. Those affected by this disorder have inadequ ...

(VLCAD deficiency) *

Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency is a rare autosomal recessive fatty acid oxidation disorder that prevents the body from converting certain fats into energy. This can become life-threatening, particularly during per ...

(LCHAD deficiency) *

Medium-chain acyl-coenzyme A dehydrogenase deficiency Medium-chain acyl-CoA dehydrogenase deficiency (MCAD deficiency or MCADD) is a disorder of fatty acid oxidation that impairs the body's ability to break down medium-chain fatty acids into acetyl-CoA. The disorder is characterized by hypoglycemia ...

(MCAD deficiency) *

Short-chain acyl-coenzyme A dehydrogenase deficiency Short-chain acyl-coenzyme A dehydrogenase deficiency (SCADD) is an autosomal recessive fatty acid oxidation disorder which affects enzymes required to break down a certain group of fats called short chain fatty acids. Signs and symptoms Short-ch ...

(SCAD deficiency) * 3-hydroxyacyl-coenzyme A dehydrogenase deficiency (M/SCHAD deficiency)

Oxidation

The term fatty acid oxidation disorder (FAOD) is sometimes used, especially when there is an emphasis on the

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

of the

fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, fr ...

. In addition to the fetal complications, they can also cause complications for the mother during pregnancy. Examples include: *

Mitochondrial trifunctional protein deficiency Mitochondrial trifunctional protein deficiency (MTP deficiency or MTPD) is an autosomal recessive fatty acid oxidation disordersubscription needed that prevents the body from converting certain fats to energy, particularly during periods without f ...

(MTPD) * MCADD,

LCHADD Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency is a rare autosomal recessive fatty acid oxidation disorder that prevents the body from converting certain fats into energy. This can become life-threatening, particularly during perio ...

, and

VLCADD Very long-chain acyl-coenzyme A dehydrogenase deficiency is a fatty-acid metabolism disorder which prevents the body from converting certain fats to energy, particularly during periods without food. Those affected by this disorder have inadequ ...

Carnitine/transport

The fatty acids are transported by

carnitine Carnitine is a quaternary ammonium compound involved in metabolism in most mammals, plants, and some bacteria. In support of energy metabolism, carnitine transports long-chain fatty acids into mitochondria to be oxidized for energy production, an ...

, and defects in this process are associated with several disorders. They involve the step immediately before oxidation, and are often grouped with the oxidation disorders.

Symptoms and signs

* Extreme sleepiness * Behavior changes * Irritable mood * Poor appetite * Fever * Nausea * Diarrhea * Vomiting * Hypoglycemia * Enlarged heart * Muscle weakness * Heart failure

Causes

Fatty-acid metabolism disorders result when both parents of the diagnosed subject are carriers of a defective gene. This is known as an autosomal recessive disorder. Two parts of a recessive gene are required to activate the disease. If only one part of the gene is present then the individual is only a carrier and shows no symptoms of the disease. If both mutated genes are present, the individual will be symptomatic. Like most autosomal recessive disorders, when both parents are carriers, there is a 25% chance for each child to inherit the disease.

Diagnosis

Diagnosis of Fatty-acid metabolism disorder requires extensive lab testing. Normally, in cases of hypoglycaemia, triglycerides and fatty acids are metabolised to provide glucose/energy. However, in this process, ketones are also produced and ketotic hypoglycaemia is expected. However, in cases where fatty acid metabolism is impaired, a non-ketotic hypoglycaemia may be the result, due to a break in the metabolic pathways for fatty-acid metabolism.

Treatment

The primary treatment method for fatty-acid metabolism disorders is dietary modification. It is essential that the blood-glucose levels remain at adequate levels to prevent the body from moving fat to the liver for energy. This involves snacking on low-fat, high-carbohydrate nutrients every 2–6 hours. However, some adults and children can sleep for 8–10 hours through the night without snacking.

Drugs

Carnitor Carnitine is a quaternary ammonium compound involved in metabolism in most mammals, plants, and some bacteria. In support of energy metabolism, carnitine transports long-chain fatty acids into mitochondria to be oxidized for energy production, an ...

- an

L-carnitine Carnitine is a quaternary ammonium compound involved in metabolism in most mammals, plants, and some bacteria. In support of energy metabolism, carnitine transports long-chain fatty acids into mitochondria to be oxidized for energy production, an ...

supplement that has shown to improve the body's metabolism in individuals with low L-carnitine levels. It is only useful for Specific fatty-acid metabolism disease.

References

External links

{{Fatty-acid metabolism disorders Fatty-acid metabolism disorders Autosomal recessive disorders