Xanthomatosis: A condition marked by the development of widespread xanthomas, yellow tumor-like structures filled with lipid deposits. Xanthomas can be found in a variety of tissues including the SKIN; TENDONS; joints of KNEES and ELBOWS. Xanthomatosis is associated with disturbance of LIPID METABOLISM and formation of FOAM CELLS.Xanthomatosis, Cerebrotendinous: An autosomal recessive lipid storage disorder due to mutation of the gene CYP27A1 encoding a CHOLESTANETRIOL 26-MONOOXYGENASE. It is characterized by large deposits of CHOLESTEROL and CHOLESTANOL in various tissues resulting in xanthomatous swelling of tendons, early CATARACT, and progressive neurological symptoms.Cholestanol: A cholesterol derivative found in human feces, gallstones, eggs, and other biological matter.Cholestanetriol 26-Monooxygenase: An NAPH-dependent cytochrome P450 enzyme that catalyzes the oxidation of the side chain of sterol intermediates such as the 27-hydroxylation of 5-beta-cholestane-3-alpha,7-alpha,12-alpha-triol.Cholestanols: Cholestanes substituted in any position with one or more hydroxy groups. They are found in feces and bile. In contrast to bile acids and salts, they are not reabsorbed.Brain Diseases, Metabolic: Acquired or inborn metabolic diseases that produce brain dysfunction or damage. These include primary (i.e., disorders intrinsic to the brain) and secondary (i.e., extracranial) metabolic conditions that adversely affect cerebral function.Sitosterols: A family of sterols commonly found in plants and plant oils. Alpha-, beta-, and gamma-isomers have been characterized.Steroid Hydroxylases: Cytochrome P-450 monooxygenases (MIXED FUNCTION OXYGENASES) that are important in steroid biosynthesis and metabolism.Chenodeoxycholic Acid: A bile acid, usually conjugated with either glycine or taurine. It acts as a detergent to solubilize fats for intestinal absorption and is reabsorbed by the small intestine. It is used as cholagogue, a choleretic laxative, and to prevent or dissolve gallstones.Lipid Metabolism, Inborn Errors: Errors in the metabolism of LIPIDS resulting from inborn genetic MUTATIONS that are heritable.Brain Diseases: Pathologic conditions affecting the BRAIN, which is composed of the intracranial components of the CENTRAL NERVOUS SYSTEM. This includes (but is not limited to) the CEREBRAL CORTEX; intracranial white matter; BASAL GANGLIA; THALAMUS; HYPOTHALAMUS; BRAIN STEM; and CEREBELLUM.Cholestanes: Derivatives of the saturated steroid cholestane with methyl groups at C-18 and C-19 and an iso-octyl side chain at C-17.Hydroxysteroids: Steroids in which one or more hydroxy groups have been substituted for hydrogen atoms either within the ring skeleton or on any of the side chains.Bile Acids and Salts: Steroid acids and salts. The primary bile acids are derived from cholesterol in the liver and usually conjugated with glycine or taurine. The secondary bile acids are further modified by bacteria in the intestine. They play an important role in the digestion and absorption of fat. They have also been used pharmacologically, especially in the treatment of gallstones.Cholestenones: CHOLESTENES with one or more double bonds and substituted by any number of keto groups.Skin Diseases, Metabolic: Diseases of the skin associated with underlying metabolic disorders.Tendons: Fibrous bands or cords of CONNECTIVE TISSUE at the ends of SKELETAL MUSCLE FIBERS that serve to attach the MUSCLES to bones and other structures.Cholestyramine Resin: A strongly basic anion exchange resin whose main constituent is polystyrene trimethylbenzylammonium Cl(-) anion.Cholic Acids: The 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholanic acid family of bile acids in man, usually conjugated with glycine or taurine. They act as detergents to solubilize fats for intestinal absorption, are reabsorbed by the small intestine, and are used as cholagogues and choleretics.Wolman Disease: The severe infantile form of inherited lysosomal lipid storage diseases due to deficiency of acid lipase (STEROL ESTERASE). It is characterized by the accumulation of neutral lipids, particularly CHOLESTEROL ESTERS in leukocytes, fibroblasts, and hepatocytes. It is also known as Wolman's xanthomatosis and is an allelic variant of CHOLESTEROL ESTER STORAGE DISEASE.Cholesterol: The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.Sterols: Steroids with a hydroxyl group at C-3 and most of the skeleton of cholestane. Additional carbon atoms may be present in the side chain. (IUPAC Steroid Nomenclature, 1987)Tabes Dorsalis: Parenchymatous NEUROSYPHILIS marked by slowly progressive degeneration of the posterior columns, posterior roots, and ganglia of the spinal cord. The condition tends to present 15 to 20 years after the initial infection and is characterized by lightening-like pains in the lower extremities, URINARY INCONTINENCE; ATAXIA; severely impaired position and vibratory sense, abnormal gait (see GAIT DISORDERS, NEUROLOGIC), OPTIC ATROPHY; Argyll-Robertson pupils, hypotonia, hyperreflexia, and trophic joint degeneration (Charcot's Joint; see ARTHROPATHY, NEUROGENIC). (From Adams et al., Principles of Neurology, 6th ed, p726)Cholic Acid: A major primary bile acid produced in the liver and usually conjugated with glycine or taurine. It facilitates fat absorption and cholesterol excretion.Bile: An emulsifying agent produced in the LIVER and secreted into the DUODENUM. Its composition includes BILE ACIDS AND SALTS; CHOLESTEROL; and ELECTROLYTES. It aids DIGESTION of fats in the duodenum.Neuromuscular Junction Diseases: Conditions characterized by impaired transmission of impulses at the NEUROMUSCULAR JUNCTION. This may result from disorders that affect receptor function, pre- or postsynaptic membrane function, or ACETYLCHOLINESTERASE activity. The majority of diseases in this category are associated with autoimmune, toxic, or inherited conditions.Achilles Tendon: A fibrous cord that connects the muscles in the back of the calf to the HEEL BONE.Phytosterols: A class of organic compounds known as STEROLS or STEROIDS derived from plants.Cytochrome P-450 Enzyme System: A superfamily of hundreds of closely related HEMEPROTEINS found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (MIXED FUNCTION OXYGENASES). In animals, these P-450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (BIOTRANSFORMATION). They are classified, according to their sequence similarities rather than functions, into CYP gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the CYP1, CYP2, and CYP3 gene families are responsible for most drug metabolism.Tendinopathy: Clinical syndrome describing overuse tendon injuries characterized by a combination of PAIN, diffuse or localized swelling, and impaired performance. Distinguishing tendinosis from tendinitis is clinically difficult and can be made only after histopathological examination.Hydroxycholesterols: Cholesterol which is substituted by a hydroxy group in any position.Chromatography, Gas: Fractionation of a vaporized sample as a consequence of partition between a mobile gaseous phase and a stationary phase held in a column. Two types are gas-solid chromatography, where the fixed phase is a solid, and gas-liquid, in which the stationary phase is a nonvolatile liquid supported on an inert solid matrix.Hydroxylation: Placing of a hydroxyl group on a compound in a position where one did not exist before. (Stedman, 26th ed)Spinocerebellar Degenerations: A heterogenous group of degenerative syndromes marked by progressive cerebellar dysfunction either in isolation or combined with other neurologic manifestations. Sporadic and inherited subtypes occur. Inheritance patterns include autosomal dominant, autosomal recessive, and X-linked.Gas Chromatography-Mass Spectrometry: A microanalytical technique combining mass spectrometry and gas chromatography for the qualitative as well as quantitative determinations of compounds.Muscular Diseases: Acquired, familial, and congenital disorders of SKELETAL MUSCLE and SMOOTH MUSCLE.