Metabolism, Inborn Errors: Errors in metabolic processes resulting from inborn genetic mutations that are inherited or acquired in utero.Amino Acid Metabolism, Inborn Errors: Disorders affecting amino acid metabolism. The majority of these disorders are inherited and present in the neonatal period with metabolic disturbances (e.g., ACIDOSIS) and neurologic manifestations. They are present at birth, although they may not become symptomatic until later in life.Lipid Metabolism, Inborn Errors: Errors in the metabolism of LIPIDS resulting from inborn genetic MUTATIONS that are heritable.Neonatal Screening: The identification of selected parameters in newborn infants by various tests, examinations, or other procedures. Screening may be performed by clinical or laboratory measures. A screening test is designed to sort out healthy neonates (INFANT, NEWBORN) from those not well, but the screening test is not intended as a diagnostic device, rather instead as epidemiologic.Purine-Pyrimidine Metabolism, Inborn ErrorsSteroid Metabolism, Inborn Errors: Errors in metabolic processing of STEROIDS resulting from inborn genetic mutations that are inherited or acquired in utero.Carbohydrate Metabolism, Inborn ErrorsUrea Cycle Disorders, Inborn: Rare congenital metabolism disorders of the urea cycle. The disorders are due to mutations that result in complete (neonatal onset) or partial (childhood or adult onset) inactivity of an enzyme, involved in the urea cycle. Neonatal onset results in clinical features that include irritability, vomiting, lethargy, seizures, NEONATAL HYPOTONIA; RESPIRATORY ALKALOSIS; HYPERAMMONEMIA; coma, and death. Survivors of the neonatal onset and childhood/adult onset disorders share common risks for ENCEPHALOPATHIES, METABOLIC, INBORN; and RESPIRATORY ALKALOSIS due to HYPERAMMONEMIA.Brain Diseases, Metabolic, Inborn: Brain disorders resulting from inborn metabolic errors, primarily from enzymatic defects which lead to substrate accumulation, product reduction, or increase in toxic metabolites through alternate pathways. The majority of these conditions are familial, however spontaneous mutation may also occur in utero.Argininosuccinic Aciduria: Rare autosomal recessive disorder of the urea cycle which leads to the accumulation of argininosuccinic acid in body fluids and severe HYPERAMMONEMIA. Clinical features of the neonatal onset of the disorder include poor feeding, vomiting, lethargy, seizures, tachypnea, coma, and death. Later onset results in milder set of clinical features including vomiting, failure to thrive, irritability, behavioral problems, or psychomotor retardation. Mutations in the ARGININOSUCCINATE LYASE gene cause the disorder.Hyperammonemia: Elevated level of AMMONIA in the blood. It is a sign of defective CATABOLISM of AMINO ACIDS or ammonia to UREA.Energy Metabolism: The chemical reactions involved in the production and utilization of various forms of energy in cells.Lipid Metabolism: Physiological processes in biosynthesis (anabolism) and degradation (catabolism) of LIPIDS.Phenylketonurias: A group of autosomal recessive disorders marked by a deficiency of the hepatic enzyme PHENYLALANINE HYDROXYLASE or less frequently by reduced activity of DIHYDROPTERIDINE REDUCTASE (i.e., atypical phenylketonuria). Classical phenylketonuria is caused by a severe deficiency of phenylalanine hydroxylase and presents in infancy with developmental delay; SEIZURES; skin HYPOPIGMENTATION; ECZEMA; and demyelination in the central nervous system. (From Adams et al., Principles of Neurology, 6th ed, p952).Smith-Lemli-Opitz Syndrome: An autosomal recessive disorder of CHOLESTEROL metabolism. It is caused by a deficiency of 7-dehydrocholesterol reductase, the enzyme that converts 7-dehydrocholesterol to cholesterol, leading to an abnormally low plasma cholesterol. This syndrome is characterized by multiple CONGENITAL ABNORMALITIES, growth deficiency, and INTELLECTUAL DISABILITY.Refractive Errors: Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.Infant, Newborn: An infant during the first month after birth.Homogentisate 1,2-Dioxygenase: A mononuclear Fe(II)-dependent oxygenase, this enzyme catalyzes the conversion of homogentisate to 4-maleylacetoacetate, the third step in the pathway for the catabolism of TYROSINE. Deficiency in the enzyme causes ALKAPTONURIA, an autosomal recessive disorder, characterized by homogentisic aciduria, OCHRONOSIS and ARTHRITIS. This enzyme was formerly characterized as EC 22.214.171.124 and EC 126.96.36.199.Homocystinuria: Autosomal recessive inborn error of methionine metabolism usually caused by a deficiency of CYSTATHIONINE BETA-SYNTHASE and associated with elevations of homocysteine in plasma and urine. Clinical features include a tall slender habitus, SCOLIOSIS, arachnodactyly, MUSCLE WEAKNESS, genu varus, thin blond hair, malar flush, lens dislocations, an increased incidence of MENTAL RETARDATION, and a tendency to develop fibrosis of arteries, frequently complicated by CEREBROVASCULAR ACCIDENTS and MYOCARDIAL INFARCTION. (From Adams et al., Principles of Neurology, 6th ed, p979)Candidiasis, Chronic Mucocutaneous: A clinical syndrome characterized by development, usually in infancy or childhood, of a chronic, often widespread candidiasis of skin, nails, and mucous membranes. It may be secondary to one of the immunodeficiency syndromes, inherited as an autosomal recessive trait, or associated with defects in cell-mediated immunity, endocrine disorders, dental stomatitis, or malignancy.Pyruvate Metabolism, Inborn Errors: Hereditary disorders of pyruvate metabolism. They are difficult to diagnose and describe because pyruvate is a key intermediate in glycolysis, gluconeogenesis, and the tricarboxylic acid cycle. Some inherited metabolic disorders may alter pyruvate metabolism indirectly. Disorders in pyruvate metabolism appear to lead to deficiencies in neurotransmitter synthesis and, consequently, to nervous system disorders.alpha-Galactosidase: An enzyme that catalyzes the hydrolysis of terminal, non-reducing alpha-D-galactose residues in alpha-galactosides including galactose oligosaccharides, galactomannans, and galactolipids.Fabry Disease: An X-linked inherited metabolic disease caused by a deficiency of lysosomal ALPHA-GALACTOSIDASE A. It is characterized by intralysosomal accumulation of globotriaosylceramide and other GLYCOSPHINGOLIPIDS in blood vessels throughout the body leading to multi-system complications including renal, cardiac, cerebrovascular, and skin disorders.Australian Capital Territory: A territory of Australia consisting of Canberra, the national capital and surrounding land. It lies geographically within NEW SOUTH WALES and was established by law in 1988.Ornithine Carbamoyltransferase Deficiency Disease: An inherited urea cycle disorder associated with deficiency of the enzyme ORNITHINE CARBAMOYLTRANSFERASE, transmitted as an X-linked trait and featuring elevations of amino acids and ammonia in the serum. Clinical features, which are more prominent in males, include seizures, behavioral alterations, episodic vomiting, lethargy, and coma. (Menkes, Textbook of Child Neurology, 5th ed, pp49-50)Argininosuccinic Acid: This amino acid is formed during the urea cycle from citrulline, aspartate and ATP. This reaction is catalyzed by argininosuccinic acid synthetase.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Isovaleryl-CoA Dehydrogenase: A mitochondrial flavoprotein, this enzyme catalyzes the oxidation of 3-methylbutanoyl-CoA to 3-methylbut-2-enoyl-CoA using FAD as a cofactor. Defects in the enzyme, is associated with isovaleric acidemia (IVA).Hypophosphatasia: A genetic metabolic disorder resulting from serum and bone alkaline phosphatase deficiency leading to hypercalcemia, ethanolamine phosphatemia, and ethanolamine phosphaturia. Clinical manifestations include severe skeletal defects resembling vitamin D-resistant rickets, failure of the calvarium to calcify, dyspnea, cyanosis, vomiting, constipation, renal calcinosis, failure to thrive, disorders of movement, beading of the costochondral junction, and rachitic bone changes. (From Dorland, 27th ed)Methylmalonic Acid: A malonic acid derivative which is a vital intermediate in the metabolism of fat and protein. Abnormalities in methylmalonic acid metabolism lead to methylmalonic aciduria. This metabolic disease is attributed to a block in the enzymatic conversion of methylmalonyl CoA to succinyl CoA.Diagnostic Errors: Incorrect diagnoses after clinical examination or technical diagnostic procedures.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.Hydroxocobalamin: Injectable form of VITAMIN B 12 that has been used therapeutically to treat VITAMIN B 12 DEFICIENCY.Pentanoic AcidsMethylmalonyl-CoA Mutase: An enzyme that catalyzes the conversion of methylmalonyl-CoA to succinyl-CoA by transfer of the carbonyl group. It requires a cobamide coenzyme. A block in this enzymatic conversion leads to the metabolic disease, methylmalonic aciduria. EC 188.8.131.52.Oxidoreductases Acting on CH-CH Group Donors: A subclass of enzymes which includes all dehydrogenases acting on carbon-carbon bonds. This enzyme group includes all the enzymes that introduce double bonds into substrates by direct dehydrogenation of carbon-carbon single bonds.Carnitine: A constituent of STRIATED MUSCLE and LIVER. It is an amino acid derivative and an essential cofactor for fatty acid metabolism.Metal Metabolism, Inborn ErrorsMetabolism: The chemical reactions that occur within the cells, tissues, or an organism. These processes include both the biosynthesis (ANABOLISM) and the breakdown (CATABOLISM) of organic materials utilized by the living organism.Fructose Metabolism, Inborn Errors: Inherited abnormalities of fructose metabolism, which include three known autosomal recessive types: hepatic fructokinase deficiency (essential fructosuria), hereditary fructose intolerance, and hereditary fructose-1,6-diphosphatase deficiency. Essential fructosuria is a benign asymptomatic metabolic disorder caused by deficiency in fructokinase, leading to decreased conversion of fructose to fructose-1-phosphate and alimentary hyperfructosemia, but with no clinical dysfunction; may produce a false-positive diabetes test.GlutaratesMaple Syrup Urine Disease: An autosomal recessive inherited disorder with multiple forms of phenotypic expression, caused by a defect in the oxidative decarboxylation of branched-chain amino acids (AMINO ACIDS, BRANCHED-CHAIN). These metabolites accumulate in body fluids and render a "maple syrup" odor. The disease is divided into classic, intermediate, intermittent, and thiamine responsive subtypes. The classic form presents in the first week of life with ketoacidosis, hypoglycemia, emesis, neonatal seizures, and hypertonia. The intermediate and intermittent forms present in childhood or later with acute episodes of ataxia and vomiting. (From Adams et al., Principles of Neurology, 6th ed, p936)Amidinotransferases: Enzymes of a subclass of TRANSFERASES that catalyze the transfer of an amidino group from donor to acceptor. EC 2.1.4.Metabolic Diseases: Generic term for diseases caused by an abnormal metabolic process. It can be congenital due to inherited enzyme abnormality (METABOLISM, INBORN ERRORS) or acquired due to disease of an endocrine organ or failure of a metabolically important organ such as the liver. (Stedman, 26th ed)Glucose: A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.Porphyria, Erythropoietic: An autosomal recessive porphyria that is due to a deficiency of UROPORPHYRINOGEN III SYNTHASE in the BONE MARROW; also known as congenital erythropoietic porphyria. This disease is characterized by SPLENOMEGALY; ANEMIA; photosensitivity; cutaneous lesions; accumulation of hydroxymethylbilane; and increased excretion of UROPORPHYRINS and COPROPORPHYRINS.Glutaryl-CoA Dehydrogenase: A flavoprotein enzyme that is responsible for the catabolism of LYSINE; HYDROXYLYSINE; and TRYPTOPHAN. It catalyzes the oxidation of GLUTARYL-CoA to crotonoyl-CoA using FAD as a cofactor. Glutaric aciduria type I is an inborn error of metabolism due to the deficiency of glutaryl-CoA dehydrogenase.Hyperargininemia: A rare autosomal recessive disorder of the urea cycle. It is caused by a deficiency of the hepatic enzyme ARGINASE. Arginine is elevated in the blood and cerebrospinal fluid, and periodic HYPERAMMONEMIA may occur. Disease onset is usually in infancy or early childhood. Clinical manifestations include seizures, microcephaly, progressive mental impairment, hypotonia, ataxia, spastic diplegia, and quadriparesis. (From Hum Genet 1993 Mar;91(1):1-5; Menkes, Textbook of Child Neurology, 5th ed, p51)Failure to Thrive: A condition of substandard growth or diminished capacity to maintain normal function.Iron Metabolism Disorders: Disorders in the processing of iron in the body: its absorption, transport, storage, and utilization. (From Mosby's Medical, Nursing, & Allied Health Dictionary, 4th ed)Metabolic Networks and Pathways: Complex sets of enzymatic reactions connected to each other via their product and substrate metabolites.Long-Chain-3-Hydroxyacyl-CoA Dehydrogenase: An NAD-dependent 3-hydroxyacyl CoA dehydrogenase that has specificity for acyl chains containing 8 and 10 carbons.Alkaptonuria: An inborn error of amino acid metabolism resulting from a defect in the enzyme HOMOGENTISATE 1,2-DIOXYGENASE, an enzyme involved in the breakdown of PHENYLALANINE and TYROSINE. It is characterized by accumulation of HOMOGENTISIC ACID in the urine, OCHRONOSIS in various tissues, and ARTHRITIS.Rare Diseases: A large group of diseases which are characterized by a low prevalence in the population. They frequently are associated with problems in diagnosis and treatment.Citrullinemia: A group of diseases related to a deficiency of the enzyme ARGININOSUCCINATE SYNTHASE which causes an elevation of serum levels of CITRULLINE. In neonates, clinical manifestations include lethargy, hypotonia, and SEIZURES. Milder forms also occur. Childhood and adult forms may present with recurrent episodes of intermittent weakness, lethargy, ATAXIA, behavioral changes, and DYSARTHRIA. (From Menkes, Textbook of Child Neurology, 5th ed, p49)Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Multiple Acyl Coenzyme A Dehydrogenase Deficiency: An autosomal recessive disorder of fatty acid oxidation, and branched chain amino acids (AMINO ACIDS, BRANCHED-CHAIN); LYSINE; and CHOLINE catabolism, that is due to defects in either subunit of ELECTRON TRANSFER FLAVOPROTEIN or its dehydrogenase, electron transfer flavoprotein-ubiquinone oxidoreductase (EC 184.108.40.206).Mucopolysaccharidoses: Group of lysosomal storage diseases each caused by an inherited deficiency of an enzyme involved in the degradation of glycosaminoglycans (mucopolysaccharides). The diseases are progressive and often display a wide spectrum of clinical severity within one enzyme deficiency.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Adenylosuccinate Lyase: An enzyme that, in the course of purine ribonucleotide biosynthesis, catalyzes the conversion of 5'-phosphoribosyl-4-(N-succinocarboxamide)-5-aminoimidazole to 5'-phosphoribosyl-4-carboxamide-5-aminoimidazole and the conversion of adenylosuccinic acid to AMP. EC 220.127.116.11.Acyl-CoA Dehydrogenase: A flavoprotein oxidoreductase that has specificity for medium-chain fatty acids. It forms a complex with ELECTRON TRANSFERRING FLAVOPROTEINS and conveys reducing equivalents to UBIQUINONE.Pyruvate Dehydrogenase Complex Deficiency Disease: An inherited metabolic disorder caused by deficient enzyme activity in the PYRUVATE DEHYDROGENASE COMPLEX, resulting in deficiency of acetyl CoA and reduced synthesis of acetylcholine. Two clinical forms are recognized: neonatal and juvenile. The neonatal form is a relatively common cause of lactic acidosis in the first weeks of life and may also feature an erythematous rash. The juvenile form presents with lactic acidosis, alopecia, intermittent ATAXIA; SEIZURES; and an erythematous rash. (From J Inherit Metab Dis 1996;19(4):452-62) Autosomal recessive and X-linked forms are caused by mutations in the genes for the three different enzyme components of this multisubunit pyruvate dehydrogenase complex. One of the mutations at Xp22.2-p22.1 in the gene for the E1 alpha component of the complex leads to LEIGH DISEASE.Lysosomal Storage Diseases: Inborn errors of metabolism characterized by defects in specific lysosomal hydrolases and resulting in intracellular accumulation of unmetabolized substrates.Ornithine-Oxo-Acid Transaminase: A pyridoxal phosphate enzyme that catalyzes the formation of glutamate gamma-semialdehyde and an L-amino acid from L-ornithine and a 2-keto-acid. EC 18.104.22.168.Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Neuroaxonal Dystrophies: A nonspecific term referring both to the pathologic finding of swelling of distal portions of axons in the brain and to disorders which feature this finding. Neuroaxonal dystrophy is seen in various genetic diseases, vitamin deficiencies, and aging. Infantile neuroaxonal dystrophy is an autosomal recessive disease characterized by arrested psychomotor development at 6 months to 2 years of age, ataxia, brain stem dysfunction, and quadriparesis. Juvenile and adult forms also occur. Pathologic findings include brain atrophy and widespread accumulation of axonal spheroids throughout the neuroaxis, peripheral nerves, and dental pulp. (From Davis & Robertson, Textbook of Neuropathology, 2nd ed, p927)Hyperoxaluria, Primary: A genetic disorder characterized by excretion of large amounts of OXALATES in urine; NEPHROLITHIASIS; NEPHROCALCINOSIS; early onset of RENAL FAILURE; and often a generalized deposit of CALCIUM OXALATE. There are subtypes classified by the enzyme defects in glyoxylate metabolism.Genetic Diseases, Inborn: Diseases that are caused by genetic mutations present during embryo or fetal development, although they may be observed later in life. The mutations may be inherited from a parent's genome or they may be acquired in utero.Fatty Acids: Organic, monobasic acids derived from hydrocarbons by the equivalent of oxidation of a methyl group to an alcohol, aldehyde, and then acid. Fatty acids are saturated and unsaturated (FATTY ACIDS, UNSATURATED). (Grant & Hackh's Chemical Dictionary, 5th ed)Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.Mass Spectrometry: An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.Homozygote: An individual in which both alleles at a given locus are identical.Pedigree: The record of descent or ancestry, particularly of a particular condition or trait, indicating individual family members, their relationships, and their status with respect to the trait or condition.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Renal Tubular Transport, Inborn Errors: Genetic defects in the selective or non-selective transport functions of the KIDNEY TUBULES.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Argininosuccinate Lyase: An enzyme of the urea cycle which splits argininosuccinate to fumarate plus arginine. Its absence leads to the metabolic disease ARGININOSUCCINIC ACIDURIA in man. EC 22.214.171.124.Biotransformation: The chemical alteration of an exogenous substance by or in a biological system. The alteration may inactivate the compound or it may result in the production of an active metabolite of an inactive parent compound. The alterations may be divided into METABOLIC DETOXICATION, PHASE I and METABOLIC DETOXICATION, PHASE II.Gas Chromatography-Mass Spectrometry: A microanalytical technique combining mass spectrometry and gas chromatography for the qualitative as well as quantitative determinations of compounds.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Fibroblasts: Connective tissue cells which secrete an extracellular matrix rich in collagen and other macromolecules.Uroporphyrinogen III Synthetase: An enzyme that catalyzes the cyclization of hydroxymethylbilane to yield UROPORPHYRINOGEN III and water. It is the fourth enzyme in the 8-enzyme biosynthetic pathway of HEME, and is encoded by UROS gene. Mutations of UROS gene result in CONGENITAL ERYTHROPOIETIC PORPHYRIA.Oxidoreductases: The class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used in cases where O2 is the acceptor. (Enzyme Nomenclature, 1992, p9)Tandem Mass Spectrometry: A mass spectrometry technique using two (MS/MS) or more mass analyzers. With two in tandem, the precursor ions are mass-selected by a first mass analyzer, and focused into a collision region where they are then fragmented into product ions which are then characterized by a second mass analyzer. A variety of techniques are used to separate the compounds, ionize them, and introduce them to the first mass analyzer. For example, for in GC-MS/MS, GAS CHROMATOGRAPHY-MASS SPECTROMETRY is involved in separating relatively small compounds by GAS CHROMATOGRAPHY prior to injecting them into an ionization chamber for the mass selection.Ornithine: An amino acid produced in the urea cycle by the splitting off of urea from arginine.Ammonia: A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.Microsomes, Liver: Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough.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.Reference Values: The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.Phlebotomy: The techniques used to draw blood from a vein for diagnostic purposes or for treatment of certain blood disorders such as erythrocytosis, hemochromatosis, polycythemia vera, and porphyria cutanea tarda.Critical Pathways: Schedules of medical and nursing procedures, including diagnostic tests, medications, and consultations designed to effect an efficient, coordinated program of treatment. (From Mosby's Medical, Nursing & Allied Health Dictionary, 4th ed)Oxidation-Reduction: A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).Blood Specimen Collection: The taking of a blood sample to determine its character as a whole, to identify levels of its component cells, chemicals, gases, or other constituents, to perform pathological examination, etc.Reproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.Diet, Protein-Restricted: A diet that contains limited amounts of protein. It is prescribed in some cases to slow the progression of renal failure. (From Segen, Dictionary of Modern Medicine, 1992)Cholesterol: The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.Urea: A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.Phenylalanine Hydroxylase: An enzyme of the oxidoreductase class that catalyzes the formation of L-TYROSINE, dihydrobiopterin, and water from L-PHENYLALANINE, tetrahydrobiopterin, and oxygen. Deficiency of this enzyme may cause PHENYLKETONURIAS and PHENYLKETONURIA, MATERNAL. EC 126.96.36.199.Consanguinity: The magnitude of INBREEDING in humans.Glycolysis: A metabolic process that converts GLUCOSE into two molecules of PYRUVIC ACID through a series of enzymatic reactions. Energy generated by this process is conserved in two molecules of ATP. Glycolysis is the universal catabolic pathway for glucose, free glucose, or glucose derived from complex CARBOHYDRATES, such as GLYCOGEN and STARCH.Acyl-CoA Dehydrogenases: Enzymes that catalyze the first step in the beta-oxidation of FATTY ACIDS.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.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Technology Assessment, Biomedical: Evaluation of biomedical technology in relation to cost, efficacy, utilization, etc., and its future impact on social, ethical, and legal systems.Kinetics: The rate dynamics in chemical or physical systems.Vitamin B 12: A cobalt-containing coordination compound produced by intestinal micro-organisms and found also in soil and water. Higher plants do not concentrate vitamin B 12 from the soil and so are a poor source of the substance as compared with animal tissues. INTRINSIC FACTOR is important for the assimilation of vitamin B 12.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Intellectual Disability: Subnormal intellectual functioning which originates during the developmental period. This has multiple potential etiologies, including genetic defects and perinatal insults. Intelligence quotient (IQ) scores are commonly used to determine whether an individual has an intellectual disability. IQ scores between 70 and 79 are in the borderline range. Scores below 67 are in the disabled range. (from Joynt, Clinical Neurology, 1992, Ch55, p28)Mutation, Missense: A mutation in which a codon is mutated to one directing the incorporation of a different amino acid. This substitution may result in an inactive or unstable product. (From A Dictionary of Genetics, King & Stansfield, 5th ed)Algorithms: A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.Genotype: The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.Nervous System Diseases: Diseases of the central and peripheral nervous system. This includes disorders of the brain, spinal cord, cranial nerves, peripheral nerves, nerve roots, autonomic nervous system, neuromuscular junction, and muscle.Liver Diseases: Pathological processes of the LIVER.Oxygen Consumption: The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)Heterozygote: An individual having different alleles at one or more loci regarding a specific character.DNA Mutational Analysis: Biochemical identification of mutational changes in a nucleotide sequence.Immunologic Deficiency Syndromes: Syndromes in which there is a deficiency or defect in the mechanisms of immunity, either cellular or humoral.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Carbon Radioisotopes: Unstable isotopes of carbon that decay or disintegrate emitting radiation. C atoms with atomic weights 10, 11, and 14-16 are radioactive carbon isotopes.Carbon Isotopes: Stable carbon atoms that have the same atomic number as the element carbon, but differ in atomic weight. C-13 is a stable carbon isotope.Lactic Acid: A normal intermediate in the fermentation (oxidation, metabolism) of sugar. The concentrated form is used internally to prevent gastrointestinal fermentation. (From Stedman, 26th ed)Insulin: A 51-amino acid pancreatic hormone that plays a major role in the regulation of glucose metabolism, directly by suppressing endogenous glucose production (GLYCOGENOLYSIS; GLUCONEOGENESIS) and indirectly by suppressing GLUCAGON secretion and LIPOLYSIS. Native insulin is a globular protein comprised of a zinc-coordinated hexamer. Each insulin monomer containing two chains, A (21 residues) and B (30 residues), linked by two disulfide bonds. Insulin is used as a drug to control insulin-dependent diabetes mellitus (DIABETES MELLITUS, TYPE 1).Alleles: Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product.Amino Acids: Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.Carbon: A nonmetallic element with atomic symbol C, atomic number 6, and atomic weight [12.0096; 12.0116]. It may occur as several different allotropes including DIAMOND; CHARCOAL; and GRAPHITE; and as SOOT from incompletely burned fuel.Mice, Knockout: Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.Lactates: Salts or esters of LACTIC ACID containing the general formula CH3CHOHCOOR.Arginine: An essential amino acid that is physiologically active in the L-form.Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.Genetic Testing: Detection of a MUTATION; GENOTYPE; KARYOTYPE; or specific ALLELES associated with genetic traits, heritable diseases, or predisposition to a disease, or that may lead to the disease in descendants. It includes prenatal genetic testing.