1 Clinical and Molecular Genetics of Congenital Adrenal Hyperplasia Due to 21-Hydroxylase Deficiency.- Introduction: Adrenal Steroidogenesis.- The Physiology of 21-Hydroxylase Deficiency.- Genetics of the 21-Hydroxylase Locus.- Southern Blotting Studies in CAH.- Gene Defects Detectable by Southern Blotting.- Point Mutations in CAH.- Prenatal Diagnosis of CAH.- References.- 2 Genetic Aspects of Amyloidosis.- Amyloidosis: Historical Background.- Amyloidosis: Definition.- Chemical Classification of the Amyloid Syndromes.- Transthyretin-Associated Amyloidosis.- Familial Mediterranean Fever and Other Hereditary Amyloidoses of the Amyloid A (AA) Type.- ACYS (Cystatin C) Hereditary Cerebral Hemorrhage with Amyloidosis: (HCHWA)-Iceland.- Aß Amyloidosis: Dutch-Type HCHWA, Alzheimer’s Disease, and Down Syndrome.- AGEL: Familial Amyloidosis of the Finnish Type.- AAPOAI: Familial Amyloid Polyneuropathy, Iowa-(Van Allen).- AC AL: Multiple Endocrine Neoplasia.- Miscellaneous Hereditary Amyloidoses.- The Treatment of Hereditary Forms of Amyloidosis.- Conclusions.- References.- 3 Huntington’s Disease.- Clinical Characteristics of HD.- Neuropathology and Neurochemistry.- Epidemiology.- A Molecular Genetic Approach to Investigation of HD.- Success of the Linkage Strategy.- Defining the HD Candidate Region.- Isolation of DNA Probes from the Candidate Region.- Fine Structure Physical Mapping of the Candidate Region.- Genetic Mapping of the Candidate Region.- Positioning of the HD Gene by Apparent Crossover Events.- Linkage Disequilibrium.- What Is the HD Gene?.- References.- 4 Biochemical and Molecular Genetics of Cystic Fibrosis.- Early Attempts to Identify Biochemical Markers for CF.- Epithelial Ion Transport.- CF Gene Mapping.- Identification of the CF Gene.- The CF Gene Product(CFTR).- Genotype and Phenotype.- Explanations for High CF Gene Frequency.- Genetic Diagnosis.- Concluding Remarks.- References.- 5 Molecular Genetics of von Recklinghausen Neurofibromatosis.- Clinical Features.- Genetics of NF1.- Biochemical and Neurobiological Aspects.- Molecular Genetics.- Future Directions.- References.- Addenda.