Introduction to Risk Calculation in Genetic Counseling, third edition is designed for counselors and clinicians to provide them with an understanding of simple probability theory so that even the most reluctant mathematician will feel comfortable when providing risk assessment in a counseling situation. It is written in a friendly and relaxed style, avoiding the sort of complex and opaque formulae that grace the pages of bewildering textbooks on statistics. Each chapter addresses a specific pattern of inheritance with detailed explanations of basic principles and how these can be applied in practice. Numerous worked examples and case scenarios have been added to many of the chapters to emphasize clinical relevance.