Genetic testing is the sampling of genes, chromosomes or proteins to determine the presence of absence of disease, to match another sample for paternity or to predict the probability of disease in the future. Commonly referred to as a DNA test, these tests involve a routine blood sample collection or saliva sample and can be done in a doctor's office, medical clinic or at home using an at-home test kit. To find out more about how genetic and DNA tests work, please read The Guide to Genetic Tests and our interviews with genetic test experts Kristine Ashcraft and Dr. Michael Baird.