The influence of copy number polymorphism on the human phenotype

The variability of human populations in a large part is determined by two complementary factors: environment and genetic information. Genetic variation is caused by different genetic variants (polymorphisms and mutations) present in the human genome. Until recently it was thought that most of these variants are small changes of one or several nucleotides (SNPs) which in their millions are present in the human genome. However, it was recently shown that there are also polymorphisms that extend over hundreds of thousands of DNA base pairs in the human genome. Such alternations called copy number variation (CNV) often include genes and other functional genetic elements. In this article we present the general characteristics of copy number polymorphism and we discuss some examples of CNVs that influence human phenotypes.