maple syrup urine disease
- maple syrup urine disease
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inherited metabolic disorder involving
leucine,
isoleucine, and
valine (a group of branch chain amino acids). Normally, these amino acids are metabolized, step by step, by a number of enzymes, each of which is specific for each step in the metabolism of each amino acid. One of the metabolic steps consists of the decarboxylation of the
α-keto acids of leucine, isoleucine, and valine, respectively. In maple syrup disease, this particular step is blocked because of defective decarboxylating enzymes. As a result, leucine, isoleucine, and valine are found to increase in concentration in the blood plasma and to overflow, together with their respective
α-keto acids, into the urine, which takes on a distinctive odour resembling that of maple syrup. Other signs of the disorder that are evident during the first few weeks of life include: poor feeding, irregular respiration, heightened muscular tension, and rigid arching of the back; the nervous system is also severely impaired. Affected infants die within several weeks unless treated. Effective treatment depends upon a diet low in leucine, isoleucine, and valine.
Two other inborn errors of metabolism involving branch chain amino acids are isovaleric acidemia and hypervalinemia. In the former, the metabolism of leucine alone is blocked at one specific step by a defect in an enzyme called isovaleryl coenzyme A dehydrogenase. As a result, the level of isovaleric acid rises markedly in body fluids, and the affected individual suffers from episodic acidosis, or decrease in alkalinity of the blood and tissues, and from slight mental impairment. In hypervalinemia, the enzyme affected is valine transaminase, and the metabolism of valine alone is abnormal. The affected infant vomits shortly after birth, fails to gain weight, and appears mentally retarded.
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Universalium.
2010.
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Maple syrup urine disease — Classification and external resources Isoleucine (pictured above), leucine, and valine are the branched chain amino acids that build up in MSUD. ICD … Wikipedia
maple syrup urine disease — ma·ple syr·up urine disease mā pəl sər əp , sir əp n a hereditary aminoaciduria caused by a deficiency of decarboxylase leading to high concentrations of valine, leucine, isoleucine, and alloisoleucine in the blood, urine, and cerebrospinal fluid … Medical dictionary
maple syrup urine disease — noun an inherited disorder of metabolism in which the urine has a odor characteristic of maple syrup; if untreated it can lead to mental retardation and death in early childhood • Syn: ↑branched chain ketoaciduria • Hypernyms: ↑ketonuria,… … Useful english dictionary
maple syrup urine disease — (aminoacidopathy) an inborn defect of amino acid metabolism causing an excess of valine, leucine, isoleucine, and alloisoleucine in the urine, which has an odour like maple syrup. Treatment is dietary; if untreated, the condition leads to mental… … Medical dictionary
maple syrup urine disease — aminoacidopathy an inborn defect of amino acid metabolism causing an excess of valine, leucine, isoleucine, and alloisoleucine in the urine, which has an odour like maple syrup. Treatment is dietary; if untreated, the condition leads to mental… … The new mediacal dictionary
Maple syrup urine disease (MSUD) — Hereditary disease due to deficiency of an enzyme involved in amino acid metabolism, characterized by urine that smells like maple syrup … Medical dictionary
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Urine — Liquid waste. The urine is a clear, transparent fluid. It normally has an amber color. The average amount of urine excreted in 24 hours is from 40 to 60 ounces (about 1,200 cubic centimeters). Chemically, the urine is mainly an aqueous (watery)… … Medical dictionary
metabolic disease — ▪ pathology Introduction any of the diseases or disorders that disrupt normal metabolism, the process of converting food to energy on a cellular (cell) level. Thousands of enzymes participating in numerous interdependent metabolic pathways… … Universalium