1 Vitamin-Responsive Inherited Metabolic Disorders.- Vitamin Deficiency: Historical Perspective.- Vitamin Responsiveness or Dependency.- Genetic Control of Vitamin Metabolism.- Biochemical Role of Vitamins.- Effect of Mutation on Vitamin Function: Theoretical Possibilities.- Defects of Vitamin Transport and Coenzyme Synthesis.- Cobalamin (Vitamin B12).- Folic Acid.- Calciferol (Vitamin D).- Defects of Coenzyme-Dependent Apoenzymes.- Pyridoxine (Vitamin B6).- Biotin.- Thiamine (Vitamin B1).- Genetic Heterogeneity.- Clinical Panorama.- Mendelian Inheritance.- Prenatal Detection and Treatment.- Problems and Perspectives.- 2 Inherited Deficiency of Hypoxanthine-Guanine Phosphoribosyltransferase in X-Linked Uric Aciduria (the Lesch-Nyhan Syndrome and Its Variants).- Clinical Presentation.- Frequency.- Complete Syndrome.- Clinical Variants of the Syndrome.- Pathology.- Biochemical Characteristics.- Primary Enzyme Defect.- Secondary Enzyme Disturbances.- Properties of the Normal Enzyme.- Properties of the Mutant Enzyme.- Mechanism of Excessive Rate of Purine Synthesis.- Mechanism of Neurological Dysfunction.- Genetic Significance.- Genetic Heterogeneity.- X-Linked Inheritance.- Chemical Selection.- Somatic Cell Genetics.- Preventive Control through Prenatal Diagnosis.- Characteristics of the Heterozygous State.- Pharmacological Consequences of HPRT Deficiency.- Diagnosis of X-Linked Uric Aciduria.- Clinical Signs.- Laboratory Tests.- Heterozygote Detection.- Treatment.- General Measures.- Medications.- 3 Hereditary Hemolytic Anemia Due to Enzyme Defects of Glycolysis.- Glucose Utilization by the Red Cell.- Overall Regulation of Glycolysis.- Mass Action Ratio.- Effect of Cell Age on Metabolism.- Molecular Genetic Mechanisms of Enzyme Deficiency.- Expression of Enzyme Defects in the Red Cell and Other Tissues.- Hexokinase Deficiency.- Clinical Spectrum.- Biochemical Considerations.- Genetic Considerations.- Glucosephosphate Isomerase Deficiency.- Clinical Spectrum.- BiochemilÁ