Brief Description of Inheritance Patterns.

Increasing data about the human genome and associations between certain genetic regions with various conditions and diseases positioned human genetics at the top of the most emerging fields in medicine. Many diagnostics algorithms and therapeutical approaches used in everyday practice are based on genetic data. Molecular genetic diagnostics covered by this book uses genetic data obtained using germline DNA. In this book, the role of somatic mutation testing will be not covered; however, in many chapters, i.e., on hereditary tumor syndromes, the role of somatic mutations as the second hit for tumorigenesis will be mentioned. Genetic variants (genotypes) identified in germline DNA are responsible for transmission of diseases (phenotypes). This chapter will briefly summarize classical inheritance patterns. Most of the heritable human diseases are transmitted in an autosomal recessive way, but others, i.e., inherited tumor syndromes, follow the autosomal dominant pattern. Nomenclature used for pedigree analysis as well as the main features of inheritance patterns are also briefly reviewed.