Gene duplication may lead to mutation and certain disorders. For instance, duplications of oncogenes cause many types of cancer, such as in the case of P70-S6 Kinase 1 amplification and breast cancer.
Gene duplication is also an important event in terms of evolution. Through duplication, many copies of genes in the genome can be produced. This would allow each gene to evolve independently to possess distinct functions. Such a set of evolutionarily related genes can be referred to as gene family.