inborn error of metabolism(redirected from Pigment defects)
Also found in: Dictionary, Thesaurus.
Related to Pigment defects: Skin Pigmentation Disorders
a defect or mistake in structure or function.
inborn error of metabolism a genetically determined biochemical disorder in which a specific enzyme defect produces a metabolic block that may have pathologic consequences at birth, as in phenylketonuria, or in later life.
measurement error the difference between what exists in reality and what is measured by a measurement method.
Type I error the rejection of a null hypothesis that is true.
Type II error acceptance of a null hypothesis that is false.
in·born er·ror of me·tab·o·lism
a group of disorders, each of which involves a disorder of a single unique enzyme, genetic in origin and operating from birth; effects are ascribable to accumulation of the substrate on which the enzyme normally acts (for example, phenylketonuria), to deficiency of the product of the enzyme (for example, albinism), or to forcing metabolism through an auxiliary pathway (for example, oxaluria).
inborn error of metabolism
one of many abnormal metabolic conditions caused by an inherited defect of a single enzyme or other protein. Although people with such diseases are defective in only one protein, they generally display a large number of physical signs that are characteristic of the genetic trait and are related to excesses or deficiencies of the substrate on which the enzyme acts. The diseases are rare. Kinds of inborn errors of metabolism include galactosemia, glucose-6-phosphate dehydrogenase deficiency, Lesch-Nyhan syndrome, phenylketonuria, and Tay-Sachs disease.
observations Inborn errors of metabolism may be detected in the fetus in utero by the examination of squamous and blood cells obtained by amniocentesis and fetoscopy. Laboratory tests after birth often show higher than normal levels of particular metabolites in the blood and urine, such as phenylpyruvic acid and phenylalanine in phenylketonuria (PKU) and galactose in galactosemia. The values are higher in homozygous than in heterozygous carriers. Signs of the various defects are usually seen only in homozygous carriers.
interventions Treatment for some pathological inborn errors may be removal of food in the diet containing the nondegradable metabolite to prevent its accumulation. Removal of dietary phenylalanine in PKU and galactose in galactosemia is effective in preventing the development of symptoms if treatment is begun early. In those cases of inborn errors of metabolism in which the nondegradable metabolite is endogenous, such as in the mucopolysaccharidoses, no treatment is available.
inborn error of metabolismAny of the expanding group, now in the hundreds, of inherited metabolic and biochemical disorders, that are divisible into those affecting
1. Small molecules–eg, simple sugars, amino or organic acids, that often have an acute onset in infancy/childhood;.
2. Large molecules–eg, ↑ in 'storage diseases'–eg, mucopolysaccharidoses and glycogen storage diseases that affect older children
Inborn errors of metabolism consequences
Loss of certain molecules–eg, albinism–defect of tyrosinase or Ehlers-Danlos disease–defect of lysyl-hydroxylase or others of a vast array of enzymes
Accumulation of normal metabolites–eg, alkaptonuria–defect of homogentisic acid oxidase or galactosemia–defect of galactose-1-phosphate uridyl transferase
Transport defects–eg, cystinuria–dibasic amino acids or intestinal disaccharidase deficiency
Defects in erythrocyte metabolism–eg, glucose-6-phosphate dehydrogenase deficiency
Pigment defects–eg, acute intermittent porphyria
Defects in mineral metabolism–eg, Wilson's disease
Vitamin defects–eg, vitamin D-dependent rickets
Defects in intestinal absorption–eg, cystic fibrosis
Other defects of unknown origin–eg, achondroplasia
inborn error of metabolisman inherited biochemical abnormality in humans due to enzymic deficiencies. The term was coined by Archibald GARROD in the early 1900s, who theorized that various conditions he had studied in hospital cases were due to defective enzymes, causing the breakdown of biochemical pathways and the build-up of intermediate chemicals in the body. Garrod's work was not recognized as important until the ONE GENE/ONE ENZYME HYPOTHESIS was proposed in the 1940s.
Inborn error of metabolism
A rare enzyme deficiency; children with inborn errors of metabolism do not have certain enzymes that the body requires to maintain organ functions. Inborn errors of metabolism can cause brain damage and mental retardation if left untreated. Phenylketonuria is an inborn error of metabolism.
Mentioned in: Mental Retardation
congenital; inherited or acquired before birth.
inborn error of metabolism
congenital disorders of metabolism. Includes cystinuria, fucosidosis, citrullinemia, mannosidosis, tyrosinemia and glycogenosis.
the sum of the physical and chemical processes by which living organized substance is built up and maintained (anabolism), and by which large molecules are broken down into smaller molecules to make energy available to the organism (catabolism).
Essentially these processes are concerned with the disposition of the nutrients absorbed into the blood following digestion.
inborn error of metabolism
a genetically determined biochemical disorder in which a specific enzyme defect produces a metabolic block that may have pathological consequences at birth, as in maple syrup urine disease of calves, or in later life, e.g. in mannosidosis in calves. See also metabolic defect.