ABSTRACT
Quantitative or complex traits are defined traditionally as traits having continuous distribution in contrast with discrete distribution. Searching for genes controlling complex or quantitative traits plays an important role in applying the genomic information to clinical diagnosis, agriculture, and forestry because a large portion of the traits related to human diseases and agronomic importance are quantitative traits. The genetics of quantitative traits are more complex than single factor Mendelian traits. These traits are usually controlled by more than a single gene and influenced by environmental effects. Traits controlled by a single gene with incomplete penetrance can be treated as quantitative traits in finding the gene. Procedures of quantitative trait loci (QTL) mapping have been derived from some specific hypothetical models. These models include the genetic models of the traits, and models for the relationship between the hypothetical QTL and genetic markers. Methods of quantitative genetics have similarly identified genetic regions regulating important functions through the genetic dissection of quantitative traits.
