of them developed features of the occipital horn syndrome in adolescence. [11). ⢠Occipital Horn Syndrome. Occipital horn syndrome (OHS), formerly called ...
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Disorders of Copper, Zinc and Iron Metabolism KuRT BAERLOCHER, MARC
Souoz
33.1 Introduction Copper, zinc and iron are essential cationic trace elements. They are transferred and utilized as inorganic ions and transported by specific carriers across membranes. They also require carriers to maintain their solubility within the intra- and extracellular compartments. Their homeostasis is controlled primarily by the gastrointestinal tract and the liver. Each of these elements has its own specific function and metabolic control [l]. The diagnosis of deficiencies or excesses of copper and zinc can be difficult, since no single test reliably indicates whether an individual is at risk. The clinical state, homeostatic mechanisms, metabolism and tissue distribution all have to be considered for the interpretation of data [I]. Copper is a component of many biologically important enzymes, such as cytochrome oxidase, superoxide dismutase, tyrosinase, dopamine-betahydroxylase, lysyl o:xidase and ceruloplasmin. Zinc plays a key role in biological functions. It stabilizes organic polymers, participates in hormone binding to nuclear and cell membrane receptors, gene transcription factors and has a regulatory and catalytic role in enzyme function. Numerous zinc metalloproteins have been identified: alkaline phosphatase, superoxide dismutasc, aminopcptidascs, angiotcnsin converting enzymes, endopeptidase, collagenase, carboxyl-peptidases and others [I ]. Iron is essential for oxygen transport and utilization and for many oxidation-reduction reactions within the cell, especially for electron transfer in mitochondria. Hemoglobin, myoglobin, cytochromes, catalase or hydroxylases are iron-containing proteins involved in oxygen binding, transport or detoxification. Transferrin and lactoferrin are iron-transporting proteins and ferritin is the iron storage protein. Both, excess or deficiency of iron may be harmful [ l ]. The inborn errors of copper, zinc and iron metabolism are related to their transport across membranes and within the cells.
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Disorders of Copper, Zinc and Iron Metabolism
• Wilson's Disease Wilson's disease (WD, hepatolenticular degeneration) is a systemic copper intoxication with a defective copper binding P-type ATPase (WND, ATP 7B). It is an autosomal recessive disorder. The gene for ATB 7B is on chromosome 13q 14.1. A large number of mutations (>60) are known [2]. Copper accumulates initially in the liver due to a reduction in biliary excretion and subsequently becomes dispersed throughout the body, especially in brain. The onset of symptoms is variable, generally between 6 and SO years of age. In childhood the hepatic form of the disease is prevalent. Later, the disease may initially present clinically with neuropsychologicaJ manifestations; however, there is always liver involvement. A Kayser-Fleischer ring is a clue for diagnosing Wilson's disease in addition to pathological liver func tion [3-S]. Biochemically, WD is defined by a low ceruloplasmin and a low serum copper (
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