Basis of Inheritance in Humans.

In humans, traits and diseases are inherited primarily by complex or multifactorial modes. These imply that contributions come from more than one gene, and these can be influenced by the environment. They are the mechanisms that underlie inheritance of dental caries, erosive tooth wear, and amelogenesis. Major gene effects (monogenic or Mendelian inheritance) and chromosomal abnormalities explain the scenarios that do not fit well with complex or multifactorial inheritance. Furthermore, there are numerous non-traditional modes of inheritance. These are all exceptions of the most common complex modes of inheritance, and their understanding is important for a number of relatively rare scenarios in humans. In this chapter, these modes of inheritance are presented, and some rare conditions are explored to highlight the relevance of studying rare diseases for the understanding of more common diseases that affect populations, using dental caries as a model.