Section 11. Inherited Disorders of Metabolism >
Part 1. Inborn Errors of Metabolism >
Chapter 134. Principles of Inborn Errors of Metabolism
Principles of Inborn Errors of Metabolism: IntroductionJean-Marie Saudubray and Joe T. R. Clarke
Topics Discussed: aciduria, organic; amino acid metabolism, inborn errors; cardiovascular finding; congenital abnormality; convulsions in the newborn; developmental delay; galactosemia; genetics and dysmorphology; hepatic disease; hypoglycemia; hypoglycemia, neonatal; hypotonia, neonatal; inborn errors of metabolism; ketosis; metabolic disorder; fatty acid; neonatal acute encephalopathy; neonatal lethargy; neonatal metabolic acidosis; neonatal screening; phenylketonurias; reference values; x-linked inheritance.
Excerpt:"Over 400 human diseases that are due to inborn errors of metabolism
are now recognized, and this number is constantly increasing. However, the
incidence of inborn errors may well be underestimated, because diagnostic
errors are frequent. Despite the relative abundance of new case
reports, there is considerable evidence that many of these disorders
remain undetected or misdiagnosed. Several factors conspire to make the
clinical diagnosis of inborn errors of metabolism (IEM) difficult.The vast majority of IEM involve abnormalities in enzymes and
transport proteins. However, all the metabolic disorders can be divided
into the following two large clinical categories.Includes disorders that either involve only one functional system
(such as the endocrine system, immune system, coagulation factors,
or lipoproteins) or affect only one organ or anatomic system (such
as the intestine, renal tubules, erythrocytes, or connective tissue).
Presenting symptoms are uniform (e.g., a bleeding tendency in coagulation
factor defects or hemolytic anemia in defects of glycolysis), and
the correct diagnosis is usually easy to guess even when the basic
biochemical lesion gives rise to systemic consequences. Visceral signs appear in lysosomal disorders. Cardiomyopathy (associated
with early neurological dysfunction, failure to thrive, and hypotonia),
sometimes responsible for cardiac failure, is suggestive of respiratory-chain
disorders, D-2-hydroxyglutaric aciduria..."
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