This chapter includes the following topics: Human Genetic Disease: A Consequence of DNA Variation A Bioinformatics Perspective on Human Disease Garrod's View of Disease Categories of Disease Classification of Disease Monogenic Disorders Complex Disorders Analysis of Chromosomal Abnormalities in Disease Human Disease Genes in Model Organisms Human Disease Organizations Functional Classification of Disease Genes Perspective Pitfalls Web Resources Discussion Questions Problems Self-Test Quiz Suggested Reading