Metabolic and Nutritional Disorders

Metabolic and Nutritional Disorders - Metabolic and...

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Metabolic and Nutritional Disorders Many are genetically inherited and represent disorders in the metabolism, use or storage of amino acids, carbohydrates or fats; other metabolic disorders are acquired and may be a consequence or sequelae of other conditions Major nutrients required for proper development and growth= both macronutrients (fat, carb and protein) and micronutrients (vitamins and minerals; essential amino acids and fatty acids) and water Nutritional disorders occur when the major macronutrients or micronutrients are either unavailable or deficient or ingested in excess Metabolism= range of biochemical processes that occur within us; breakdown and its transfer unto energy; anabolism= build up; catabolism= break down Metabolic Disorders 1. Genetically determined errors or metabolism (inborn errors of metabolism; rare, well described and mostly occur in children) Associated with specific enzyme deficiencies and result in blockage of amino acid, carb or lipid metabolism, with reduction of some substances and accumulation of others; function and/or morphologic changes may occur and in some instances (phenylketonuria, galactosemia) may be ameliorated by therapy; in many disorders the carrier state can be identified to permit genetic counselling; by testing of amniotic fluid before birth of appropriate screening at birth, these metabolic disorders can be detected; these disorders seldom occur so the utero testing can usually assure that their child will be normal Many are characterized by autosomal recessive transmission and in many cases the chromosome on which the defective gene is located has been determined; functional and pathological damage may be produced by loss of end product of a reaction due to enzyme deficiency, accumulation of substances prior to the metabolic block, or production of toxic metabolites; indirect effects also exerted on other metabolic pathways or functional elements Clinical expression: neurological complications present in many of these disorders range from specific focal abnormalities to mental retardation; precise reason for the mental retardation is not clear; marked variation in the age of onset, rate of progression and organ and skeletal involvement among disorders and among variants of each disorder (due to factors such as different isoenzymes involved, solubility of accumulated products for excretion and the specific biochemical reactions occurring in various organs) Phenylketonuria= disorder of amino acid metabolism in which the enzyme responsible for the conversion of phenylalanine to tyrosine is deficient ( phenylalanine hydroxylase ); affects 1/12 000 live births; autosomal recessive ; born with it; results in increased blood levels of phenylalanine= impairs normal brain development, and increased urinary excretion of phenylpyruvic acid; morpholocially within the brain there is hypomyelination ; gliosis; microcephaly; and no lysosomal storage in neurons; we get phenylalanine strictly from our diet (protein rich foods);
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This note was uploaded on 02/08/2012 for the course PATHOLOGY 3245 taught by Professor X during the Spring '11 term at UWO.

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Metabolic and Nutritional Disorders - Metabolic and...

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