The expanding field of genetics and growing research linking mutations in specific genes to increased risk of cancer (cancer susceptibility genes) have rapidly expanded the field of predictive genetic testing. Predictive genetic testing may help identify people who are at an increased risk for developing certain types of cancer, but also carries many limitations and risks. People need to fully understand the process and its implications.
A gene is a hereditary unit of DNA that occupies a specific location on a chromosome. Genes carry directions to cells and tell them to make specific proteins that perform and regulate all body functions. Genes are capable of replicating themselves at each cell division. A mutation is a change in the usual DNA sequence of a particular gene. Mutations can be beneficial, harmful, or neutral. Many diseases, including cancer, begin in the genes. The genetic mutation that causes cancer can be inherited from a parent or it can be a random mutation that occurs as a result of a mistake during cell division or in response to environmental factors.
Current research suggests that only 5-10% of cancers are inherited. This hereditary influence begins with the genes that are passed from parent to child. Genes come in pairs, with one copy inherited from each parent. Parents can pass on a normal copy or, if they have one, an abnormal or mutated copy of a gene. Determining the probability of inheriting a gene mutation and/or of developing cancer as a result of a gene mutation is a complicated process that requires an understanding of heredity, genetics and the role of genes.