The definition of gene has progressed from being an abstract unit of heredity in Mendel’s time to our current concept of a tangible molecular entity capable of replication, expression, and mutation (Figure 15.1). Currently, we can perform tests for many genetic diseases, but these tests create ethical and legal issues. For example, would you want to be tested for a debilitating genetic disease if there was the possibility insurance companies could use that information to deny you coverage? Fortunately, the Genetic Information Nondiscrimination Act of 2008 protects American citizens from discrimination from both insurance companies and employers based on genetic information. More information about policy, legal, and ethical issues in genetic research can be found here.