Biochemistry · Clinical Biochemistry and Laboratory Medicine

Inborn errors of metabolism: principles and selected examples

7 min read

Quick Orientation

Section	Objective	Keywords
Definition	Understand the core idea	Inborn errors of metabolism (IEM)
Disorders of Tyrosine (Phenylalanine) Metabolism	Follow the sequence and key control points	Phenylketonuria (PKU), phenylalanine hydroxylase, Alkaptonuria
Inborn Errors of Sulfur Amino Acid Metabolism	Follow the sequence and key control points	Cystinuria, cysteine, ornithine, arginine, lysine (COAL), cystathionine synthase
Metabolic Defects of Branched Chain Amino Acids	Learn the main facts and relationships	Maple syrup urine disease (MSUD), branched chain α-keto acid dehydrogenase
Disorders of Galactose Metabolism	Follow the sequence and key control points	Classical galactosemia, galactose 1-phosphate uridyltransferase, Galactokinase deficiency
Clinical Correlation	Connect the mechanism to clinical findings	PKU, Guthrie bacterial bioassay, Alkaptonuria

Section

Definition

Objective: Understand the core idea
Keywords: Inborn errors of metabolism (IEM)

Disorders of Tyrosine (Phenylalanine) Metabolism

Objective: Follow the sequence and key control points
Keywords: Phenylketonuria (PKU), phenylalanine hydroxylase, Alkaptonuria

Inborn Errors of Sulfur Amino Acid Metabolism

Objective: Follow the sequence and key control points
Keywords: Cystinuria, cysteine, ornithine, arginine, lysine (COAL), cystathionine synthase

Metabolic Defects of Branched Chain Amino Acids

Objective: Learn the main facts and relationships
Keywords: Maple syrup urine disease (MSUD), branched chain α-keto acid dehydrogenase

Disorders of Galactose Metabolism

Objective: Follow the sequence and key control points
Keywords: Classical galactosemia, galactose 1-phosphate uridyltransferase, Galactokinase deficiency

Clinical Correlation

Objective: Connect the mechanism to clinical findings
Keywords: PKU, Guthrie bacterial bioassay, Alkaptonuria