Engineering and Applications of Chimeric Nucleases

Each human cell contains about 3xl09 base pairs (bp) within its genome. With the first draft sequence of the human genome now available, biologists estimate that there are about 30,000-40,000 different genes within the genome (IHGSC2001,Venter et al. 2001). This is fewer than originally anticipated, but still a huge number. These genes code for all of the human body’s proteins. Simple mutations within the coding region of critical genes can lead to the formation of abnormal proteins, resulting in disease phenotypes, premature death, or failure of an embryo to develop. Furthermore, mutations that affect the regulatory region of genes can result in aberrant gene expression within cells, and give rise to cancer phenotypes. The ‘Holy Grail’ of the Human Genome Project is ‘Gene Therapy’, that is,how genes might someday be used, modified, or even changed to correct human disease.