![]() ![]() It can be tested to screen newborns for MSUD.ĭialysis -A method of artificial kidney function used to remove waste products or other substances from the patient’s body fluids. MSUD is an autosomal recessive disorder.īranched-chain alpha-keto acid dehydrogenase (BCKD) -The chemical name of the enzyme that is missing or partially inactivated in patients with MSUD.Ĭarrier -A person who harbors an infectious agent or a defective gene without showing clinical signs of disease themselves and who can transmit the infection to others or the defective gene to their children.Ĭerumen -The waxy substance secreted by glands in the external ear canal. ![]() The three amino acids involved in MSUD are called branched-chain amino acids or BCAAs because their chemical structures have side chains of carbon atoms that form a branch rather than a straight line.Īutosomal recessive -A term used to describe a pattern of genetic inheritance in which a child receives two copies of a defective gene, one from each parent, on an autosome (a nonsex chromosome). KEY TERMSĪmino acid -One of 20 organic acids used as the building blocks of proteins in humans and other animals. In the classical (most severe) form of the disease, a baby born with MSUD develops a severe acidosis (abnormally high levels of acid in the blood) during the first week of life, followed by seizures and coma caused by swelling of the brain tissue, and finally death. In all three cases, the three BCAAs and their byproducts, which are called ketoacids, build up in the urine, blood, and other body tissues. The patient may lack the enzyme complex entirely, it may be inactivated, or it may be only partially active. A person diagnosed with MSUD lacks the enzyme complex that is needed to break down the three BCAA s. MSUD is an inborn metabolic disorder ( IMD ), which means that it is a heritable disease characterized by the body’s inability to process one or more specific substances essential to health. Description Maple syrup urine disease (MSUD) The MSUD diet of the early 2000s as modified for different age groups is described in further detail below. Dietary therapy of MSUD thus consists of a combination of protein substitutes containing amino acids without any BCAAs, and enough low-protein or protein-free foods to meet the patient’s daily caloric requirements. Most protein-rich foods, such as meat, dairy products, and eggs, however, contain high levels of BCAA s. Snyderman and his colleagues reported on the first successful dietary therapy for MSUD in 1964, which they accomplished by restricting the patients’ intake of foods containing high levels of branched-chain amino acids. ![]() The deficient enzyme, now known as branched-chain alpha-keto acid dehydrogenase complex, or BCKD, was purified and defined in 1978.įollowing Dancis’s work, S. (Illustration by GGS Information Services/Thomson Gale.)īreak down three branched-chain amino acids-leucine, isoleucine, and valine-during the process of digestion. In 1960, a researcher named Dancis established that the metabolic block in MSUD is caused by an insufficient supply of an enzyme that helps to An effective treatment, however, had to await further biochemical analysis of the metabolic dysfunction underlying the disease. The urine of these infants smelled like maple syrup or burned sugar, whence the disease got its name of maple syrup urine disease or MSUD. The family in Menkes’s case study had lost four infants within the first 3 months of life to a previously undescribed degenerative disorder of the nervous system. Menkes, a pediatrician, and his colleagues. Strict adherence to this diet is necessary to prevent developmental delays, mental retardation, and recurrent metabolic crises leading to respiratory failure and death. ![]() The special diet associated with MSUD is a low-protein diet characterized by restriction of a specific amino acid known as leu-cine the use of high-calorie liquid or gel formulas that are free of branched-chain amino acids ( BCAA s) and frequent monitoring of the BCAA levels in the patient’s blood plasma. Maple syrup urine disease ( MSUD ), which is also known as branched-chain ketoaciduria, branched-chain alpha-keto acid dehydrogenase deficiency, or BCKD deficiency, is a rare but potentially fatal inherited metabolic disorder ( IMD ) passed down in an autosomal recessive pattern. ![]()
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