Gene tests are already available for some two dozen disorders, including life-threatening diseases such as cystic fibrosis and Tay Sachs disease.

Gene tests for some cancers are also available. Specific genetic mutations have been identified as linked to several types of cancer, and, for some cancer types, this information has been converted into clinical tests. For example, scientists identified gene mutations that are linked to an inherited tendency to develop colon or breast cancer, and tests for an inherited susceptibility to these cancers are commercially available.