$Unique_ID{BRK03983} $Pretitle{} $Title{Medium-Chain Acyl CoA Dehydrogenase Deficiency} $Subject{Medium-Chain Acyl CoA Dehydrogenase Deficiency Acyl CoA Dehydrogenase Deficiency, Medium-Chain Nonketotic Carnitine Deficiency Carnitine Deficiency MCAD Deficiency MCADH Deficiency Dicarboxylicaciduria Glutaricaciduria II Reye Syndrome } $Volume{} $Log{} Copyright (C) 1988, 1989 National Organization for Rare Disorders, Inc. 585: Medium-Chain Acyl CoA Dehydrogenase Deficiency ** IMPORTANT ** It is possible that the main title of this article (Medium-Chain Acyl CoA Dehydrogenase Deficiency) is not the name you expected. Please check the SYNONYM list to find the alternate names and disorder subdivisions covered by this article. Synonyms Acyl CoA Dehydrogenase Deficiency, Medium-Chain Nonketotic Carnitine Deficiency Carnitine Deficiency MCAD Deficiency MCADH Deficiency Dicarboxylicaciduria Information on the following disorders can be found in the Related Disorders section of this report: Glutaricaciduria II Reye Syndrome General Discussion ** REMINDER ** The information contained in the Rare Disease Database is provided for educational purposes only. It should not be used for diagnostic or treatment purposes. If you wish to obtain more information about this disorder, please contact your physician and/or the agencies listed in the "Resources" section of this report. Medium-Chain Acyl CoA Dehydrogenase Deficiency (MCAD) is a metabolic disorder characterized by a deficiency of the enzyme medium chain CoA dehydrogenase which is needed for the breakdown of medium chain fatty acids. This enzyme plays a central role in the metabolism of fats. Low blood sugar (hypoglycemia), lack of energy (lethargy) and possibly coma, as well as fatty changes in the liver, may also occur. During hypoglycemic periods, tests usually show massive amounts of dicarboxylic acid in the urine. Symptoms Medium-Chain Acyl CoA Dehydrogenase Deficiency is a form of organic acidemia. It is characterized by intermittent low blood sugar levels (hypoglycemia) after fasting, as well as fatigue, and sometimes coma. During periods of hypoglycemia, tests usually show excessive amounts of dicarboxylic acids in the urine of 6 to 8 carbon atoms in length. The chemical compound suberylglycine appears to be diagnostic for this condition. Fatty changes in the liver may also occur. Symptoms first appear during childhood or early adolescence. Causes CoA Dehydrogenase Deficiency is a hereditary disorder transmitted through autosomal recessive genes. (Human traits, including the classic genetic diseases, are the product of the interaction of two genes for that condition, one received from the father and one from the mother. In recessive disorders, the condition does not appear unless a person inherits the defective gene for the same trait from each parent. If a person receives one normal gene and one gene for the disease, he or she will be a carrier for the disease, but usually will show no symptoms. The risk of transmitting the disease to the children of a couple, both of whom are carriers for a recessive disorder, is 25 percent. Fifty percent of their children will be carriers, but healthy as described above. Twenty-five percent of their children will receive both normal genes, one from each parent, and will be genetically normal.) Affected Population Medium-Chain Acyl CoA Dehydrogenase Deficiency has an incidence of about 1 in 10,000 live births. It first appears during infancy and early childhood and males and females are affected in equal numbers. Related Disorders Symptoms of the following disorders are similar to those of Medium-Chain Acyl CoA Dehydrogenase Deficiency. Comparisons may be useful for a differential diagnosis: Glutaricaciduria II: There are two forms of this disorder which occur during different stages of life. They are both forms of organic acidemias which are a group of metabolic disorders characterized by excess acid in the blood and urine. 1) Glutaricaciduria IIA (GA IIA). This neonatal form of Glutaricaciduria II is a very rare, sex-linked hereditary disorder characterized by large amounts of glutaric and other acids in blood and urine. Some researchers believe the disorder is caused by a defect in the breakdown of acyl-CoA compounds. 2) Glutaricaciduria IIB (GA IIB; Ethylmalonic Adipicaciduria) is the milder, adult form of Glutaricaciduria II. This disorder, inherited through autosomal recessive genes, is characterized by acidity of the body tissues (metabolic acidosis), and a low blood sugar level (hypoglycemia) without an elevated level of ketones in body tissues (ketosis). Large amounts of glutaric acid in the blood and urine are caused by a deficiency of the enzyme "Multiple acyl-CoA dehydrogenase". (For more information, choose "Glutaricaciduria II" as your search term in the Rare Disease Database.) Reye Syndrome is a combination of acute brain disease (encephalopathy) and fatty degeneration of the abdominal organs. This disorder tends to follow some acute viral infections such as flu or chicken pox in combination with certain toxic substances such as aspirin. In addition to these viruses and toxins, deficiencies of the enzymes needed in the breakdown of ammonia to urine appear to be a contributing factor. Symptoms occur suddenly and progress quickly, leading to coma. (For more information, choose "Reye" as your search term in the Rare Disease Database.) Therapies: Standard Symptoms of Medium-Chain Acyl CoA Dehydrogenase Deficiency may be prevented by not allowing children with this deficiency to fast for prolonged periods of time. Sometimes children have to be awakened at night for feedings. Others may be fed intravenously or parenterally overnight. The usefulness of restricting the amino acids lysine, hydroxylysine and tryptophan (which generate glutaric acid when they are metabolized) is not established at the present time. Acute episodes of acidity in blood and body tissues (acidosis) and dehydration are treated with fluids and bicarbonate. Many of the adverse effects of organic acidemias are due to secondary carnitine depletion. Such patients should have plasma carnitine measured and, if deficient, begin a supplement of 100-300 mg/kg/day of oral l-carnitine. Other treatment is symptomatic and supportive. Therapies: Investigational This disease entry is based upon medical information available through December 1989. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder. Resources For more information on medium Chain Acyl CoA Dehydrogenase Deficiency, please contact: National Organization for Rare Disorders (NORD) P.O. Box 8923 New Fairfield, CT 06812-1783 (203) 746-6518 Support Group for Medium Chain Acyl CoA Dehydrogenase Deficiency (MCAD) 805 Montrose Dr. Greensboro, NC 27410 (919) 547-0196 Organic Acidemia Association 522 Lander St. Reno, NV 89512 (702) 322-5542 British Organic Acidemia Association 5 Saxon Rd. Ashford, Middlesex TW15 1QL England National Digestive Diseases Information Clearinghouse Box NDDIC Bethesda, MD 20892 (301) 468-6344 Research Trust for Metabolic Diseases in Children Golden Gates Lodge, Weston Rd. Crewe CW1 1XN, England Telephone: (0270) 250244 For information on genetics and genetic counseling referrals, please contact: March of Dimes Birth Defects Foundation 1275 Mamaroneck Avenue White Plains, NY 10605 (914) 428-7100 Alliance of Genetic Support Groups 35 Wisconsin Circle, Suite 440 Chevy Chase, MD 20815 (800) 336-GENE (301) 652-5553 References MENDELIAN INHERITANCE IN MAN, 7th ed.: Victor A. McKusick; Johns Hopkins University Press, 1986. Pp. 800-801. THE METABOLIC BASIS OF INHERITED DISEASE, 5th ed.: John B. Stanbury, et al., eds; McGraw Hill, 1983. P. 238. CATALYTIC DEFECT OF MEDIUM-CHAIN ACYL COENZYME A DEHYDROGENASE DEFICIENCY: LACK OF BOTH COFACTOR RESPONSIVENESS AND BIOCHEMICAL HETEROGENEITY IN EIGHT PATIENTS: B.A. Amendt, et al.; J Clin Investi (1985: issue 76). Pp. 963-969. DICARBOXYLIC ACIDURIA: DEFICIENT 1-(14)C-OCTANOATE OXIDATION AND MEDIUM- CHAIN ACYL-CoA DEHYDROGENASE IN FIBROBLASTS: W.J. Rhead, et al.; Science (1983: issue 221). Pp. 73-75.