Genes, which are carried on chromosomes, are the basic physical and functional units of heredity. Genes are specific sequences of bases that encode instructions on how to make proteins. Although genes get a lot of attention, it’s the proteins that perform most life functions and even make up the majority of cellular structures. When genes are altered so that the encoded proteins are unable to carry out their normal functions, genetic disorders can result. Gene therapy is an experimental treatment that involves introducing genetic material into a person’s cells to fight disease. Gene therapy is being studied in clinical trials for many different types of cancer and for numerous other diseases. The volume presents significant new research results in this promising field.