1 Cytogenetics of Pregnancy Wastage.- Estimation of Pregnancy Wastage.- Evaluation of the Incidence of Chromosome Abnormalities.- Spontaneous Abortions.- Induced Abortions.- Perinatal Deaths.- Types of Chromosome Abnormalities.- Autosomal Trisomies and Monosomies.- Sex Chromosome Aneuploidies.- Errors of Chromosome Haploid Sets.- Mosaicism.- Structural Anomalies.- Animal Model for Meiotic Nondisjunction and Experimentally Induced Monosomy and Trisomy.- Model for the Study of Meiotic Malsegregation and Preferential Segregation of Rb Chromosomes.- Model of Multiple Rb Heterozygosity for Production of High Rates of First Meiotic Anaphase Nondisjunction and Evaluation of Prenatal Losses.- Developmental Profiles of Monosomy and Trisomy: Principles and Mechanisms of Abnormal Development.- Perspectives for Studies in the Mouse.- Conclusion.- References.- 2 Mutation in Human Populations.- Classes of Mutation.- Classification by Phenotypic Effect.- Classification by Genomic Effect.- Number and Incidence of Human Mendelian Traits.- Mutation Rate Estimates.- Methods.- Results.- Some Special Problems.- Parental Age Effects.- Sex Differences in Mutation Rates.- Heterogeneity of Mutation Rates.- Population Monitoring.- Use of Mutation Rates in Genetic Counseling.- Population Kinetics of Mutation.- Equilibrium between Mutation and Selection.- The Rarity of Complete Recessivity.- Effects of a Change of Mutation Rate and of Environment.- The Effect of a Single Burst of Mutations.- Assessing the Population Mutation Burden.- The Mutation Load and Mutation Impact.- The Mutation Component of Genetic Disease.- Mutation and Evolution.- The Importance of Mutation Rate in Evolution.- Evolutionary Adjustment of Mutation Rates.- The Human Population.- References.- 3 Genetic Mutations Affecting Human Lipoprotein Metabolism.- General Review.- Pathway of Lipoprotein Metabolism.- Apoprotein Structure and Function.- Mutations in the Pathway of Lipoprotein Metabolism.- Mutations in LDL Receptor Pathway.- Mutations in Apoproteins.- Mutations in Enzymes Participating in Lipoprotein Catabolism.- Future Directions.- References.- 4 Giucose-6-Phosphate Dehydrogenase.- Glucose-6-Phosphate Dehydrogenase in Evolution.- Evolution of Enzyme Structure and Function.- Evolution of Genetic Variability.- Evolution of Expression.- The G6PD Gene in Humans.- Cloning of cDNA.- The Gd Gene and the X Chromosome.- Gd Mutants in Cultured Cells.- Genetic Variability of Human G6PD.- General Patterns of Variation.- Polymorphic Nondeficient Variants.- Polymorphic Deficient Variants.- Are Some G6PD Mutants Double Mutants'.- Expression of G6PD and G6PD Deficiency.- G6PD Deficiency in Erythrocytes.- G6PD and G6PD Deficiency in Nonerythroid Cells.- Acquired Changes.- G6PD Polymorphism and Malaria Selection.- Summary of Evidence.- In vitro Culture Work.- Objections.- Conclusion.- Concluding Remarks.- References.- 5 Steroid Sulfatase Deficiency and the Genetics of the Short Arm of the Human X Chromosome.- Sulfated Steroids and their Metabolism.- Cholesterol Sulfate.- DHEA Sulfate.- DHEAS and Estrogen Production.- Steroid Sulfatase (STS).- Steroid Sulfatase Deficiency.- Clinical Features of Steroid Sulfatase Deficiency.- X-linked Ichthyosis.- Testicular Abnormalities.- Steroid Metabolism in STS Deficiency.- Testicular Metabolism in STS Deficiency.- Genetics of Steroid Sulfatase.- Somatic Cell Studies.- Deletion Mapping.- STS in Other Species.- Some Genes on the Human X-chromosome Short Arm Are Not Inactivated.- STS Is Not Inactivated.- The MIC2X and MIC2Y Loci.- Inactivation and Structurally Abnormal X Chromosomes.- STS and Studies of X Inactivation.- Pairing and Recombination of X and Y Chromosomes.- Conclusion.- References.- Addenda.