1 Chapter 43 Inborn Metabolic Defects of Lysosomes, Peroxisomes, Carbohydrates, Fatty Acids and Mitochondria Copyright © 2012, American Society for Neurochemistry

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Chapter 43

Inborn Metabolic Defects of Lysosomes,Peroxisomes, Carbohydrates, Fatty Acids

and Mitochondria

Copyright © 2012, American Society for Neurochemistry. Published by Elsevier Inc. All rights reserved.

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TABLE 43-1: Lysosomal Storage Diseases


3Copyright © 2012, American Society for Neurochemistry. Published by Elsevier Inc. All rights reserved.

TABLE 43-1: Lysosomal Storage Diseases

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TABLE 43-2: Diseases of Peroxisomal Biogenesis


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TABLE 43-3: Single Peroxisomal Enzyme Diseases


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TABLE 43-4: Clinical Features of Mitochondrial Diseases Associated with mtDNA Mutations


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FIGURE 43-1: Electron micrograph of a Twitcher myelinated axon. The cross-section of this sciatic nerve was taken from a sick mutant mouse and shows an axon engulfed by its Schwann cell. The cytoplasm of the myelinating Schwann cell is filled with enlarged vacuoles and membrane structures. Crystallized deposits of undigested material, also known as Krabbe crystals, are clearly visible (arrows). Bar: 500 nm. (Courtesy of Robert P. Becker et al., College of Medicine, University of Illinois at Chicago).


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FIGURE 43-2: Schematic representation of glycogen metabolism and glycolysis. Roman numerals indicate the sites of identified enzyme defects: I, glucose-6-phosphatase; II, acid maltase; III, debrancher enzyme; IV, brancher enzyme; V, muscle phosphorylase; VI, liver phosphorylase; VII, phosphofructokinase; VIII, phosphorylase kinase; IX, phosphoglycerate kinase; X, phosphoglycerate mutase; XI, lactate dehydrogenase; XII, aldolase; XIII, β-enolase. GLUT 1, glucose transporter; P, phosphate; PEP, phosphoenolpyruvate; PLD, phosphorylase-limit dextrin; UDPG, uridine diphosphate glucose.


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FIGURE 43-3: Schematic representation of fatty acid oxidation. This metabolic pathway is divided into the carnitine cycle (A), the inner mitochondrial membrane system (B), and the mitochondrial matrix system (C). The carnitine cycle includes the plasma membrane transporter (Tp), carnitine palmitoyltransferase I (CPT I), the carnitine–acylcarnitine translocase system (Tl) and carnitine palmitoyltransferase II (CPT II). The inner mitochondrial membrane system includes the very-long-chain acyl-CoA dehydrogenase (VLCAD) and the trifunctional protein with three catalytically active sites. Long-chain acylcarnitines enter the mitochondrial matrix by the action of CPT II to yield long-chain acyl-CoAs. These thioesters undergo one or more cycles of chain shortening catalyzed by the membrane-bound system. Chain-shortened acyl-CoAs are degraded further by the matrix β-oxidation system. Medium-chain fatty acids enter the mitochondrial matrix directly and are activated to the medium-chain acyl-CoAs before degradation by the matrix β-oxidation system. AD, acyl-CoA dehydrogenase; AS, acyl-CoA synthetase; CoA, coenzyme A; CPT, carnitine palmitoyltransferase; EH, 2-enoyl-CoA hydratase; HD, 3-hydroxyacyl-CoA dehydrogenase; KT, 3-ketoacyl-CoA thiolase; LC, long chain; MC, medium chain; SC, short chain; TL, carnitine-acylcarnitine translocase; Tp, carnitine transporter; VLC, very long chain. (With permission from reference Platt & Walkley, 2004.)


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FIGURE 43-4: Schematic representation of mitochondrial metabolism. Respiratory chain complexes or components encoded exclusively by the nuclear genome are light orange. Complexes containing some subunits encoded by the nuclear genome and others encoded by mitochondrial DNA are dark orange. CPT, carnitine palmitoyltransferase; PDHC, pyruvate dehydrogenase complex; CoA, coenzyme A; TCA, tricarboxylic acid; CoQ, coenzyme Q; Cyt c, cytochrome c. (Modified from reference (Conradi et al., 1984), with permission of McGraw-Hill, New York).


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1 Chapter 43 Inborn Metabolic Defects of Lysosomes, Peroxisomes, Carbohydrates, Fatty Acids and Mitochondria Copyright © 2012, American Society for Neurochemistry