Acylcarnitine Profile

Fatty Acid Oxidation Disorders

Carnitine/Acylcarnitine Translocase (CACT) Deficiency

Carnitine/Acylcarnitine Translocase (CACT) Deficiency is a disorder of fatty acid oxidation. Fatty acid oxidation generates ATP in the mitochondria and provides acetyl-CoA for gluconeogenesis. CACT normally acts to transport long-chain acylcarnitine across the inner mitochondrial membrane into the mitochondrial matrix where ß-oxidation occurs. CACT also facilitates the export of free carnitine out of the mitochondria where it can be utilized for formation of acylcarnitines. Deficiency of this transport protein results in impaired long-chain fatty acid oxidation and causes the accumulation of long-chain acylcarnitines outside the mitochondria and in plasma. Short- and medium-chain (C8 and less) fatty acids do not require CACT for entry into the mitochondria and are therefore available for energy metabolism.

Carnitine Palmitoyl Trtansferase Deficiency Type 1

Carnitine palmitoyltransferase I deficiency is a condition that prevents the body from converting certain fats called long-chain fatty acids into energy, particularly during periods without food (fasting). Carnitine, a natural substance acquired mostly through the diet, is required by cells to process fats and produce energy. People with this disorder have a faulty enzyme that disrupts carnitine's role in processing long-chain fatty acids.

One of the main signs of this disorder is a low level of ketones, which are products of fat breakdown that are used for energy. Low blood sugar (hypoglycemia) is another major feature. Together these signs are called hypoketotic hypoglycemia, which can result in a loss of consciousness or seizures. People with this disorder typically also have an enlarged liver (hepatomegaly), muscle weakness, nervous system damage, and elevated levels of carnitine in the blood.

This condition is sometimes mistaken for Reye syndrome, a severe disorder that develops in children while they appear to be recovering from viral infections such as chicken pox or flu. Most cases of Reye syndrome are associated with the use of aspirin during these viral infections

This condition is rare; there are fewer than 50 individuals identified with this disorder. This disorder may be more common in the Hutterite populations of the northern United States and Canada, and in the Inuit populations of northern Canada, Alaska, and Greenland.

Disorders Detected By Tandem Mass Spectrometry

With the development of tandem mass spectrometry in the early 1990s, the number of detectable diseases has increased, especially in the categories of Fatty Acid Oxidation Disorders & Organic Acid Disorders. Screening tests for the disorders listed below (and an increasing number of others) are now available, though not universally mandated.

1.  Hemoglobinopathies

 Hemoglobin S-Beta Thalassemia
 Hemoglobin S/C Disease
 Beta Thalassemia Major
 Hemoglobin E Beta Thalassemia
 Sickle Cell Disease

2.  Biochemical Panel

 Biotinidase Deficiency
 Congenital Adrenal Hyperplasia
 Congenital Hypothyroidism
 Cystic Fibrosis

3.  Aminoacidopathies

 Maple Syrup Urine Disease
 Phenylketonuria (biopterin Cofactor defects of regeneration and biosynthesis)
 Tyrosinemia Type I
 Tyrosinemia Type II
 Tyrosinemia Type III

4.  Fatty Acid Oxidation Disorders

 Carnitine/Acylcarnitine Translocase Deficiency
 Carnitine Palmitoyl Transferase Deficiency Type II
 Carnitine Uptake Defect
 2,4 Dienoyl-CoA Reductase Deficiency
 Glutaric Acidemia Type II
 Long Chain 3-Hydroxyacyl-CoA Dehydrogenase
 Medium Chain Acyl-CoA Dehydrogenase Deficiency
 Medium-Short Chain Hydroxyl Acyl-CoA Dehydrogenase Deficiency
 Medium Chain 3-Ketoacyl-CoA Thiolase Deficiency
 Trifunctional Protein Deficiency
 Very Long Chain Acyl-CoA Dehydrogenase Deficiency (VLCHAD)