The number of human genes has been the subject of debate, with estimates ranging from 120,000 to 30,000. Recent best estimates are that the number is less than 50,000. As of today, the assembled sequence of the human genome will be available from a number of sources, following publication of the work of Celera Genomics Group and colleagues in Science, providing hard figures on the number of genes, their locations on chromosomes and the total number of possible proteins.

While a low number may sound like bad news for companies that are looking for unique targets, the good news is that understanding all the human