Until now, the main estimates have ranged from 65,000 to 120,000. But two research teams, using independent methods, estimate there may be as few as 30,000 or 34,000 genes. However, a third group, which also reports its work in the journal Nature Genetics, has come up with a figure of 120,000 genes. The number of genes, and their location and function, is of intense interest to medical researchers who are searching for new ways to treat disease.
ESTs represent parts of genes and can be easily synthesised in the laboratory.
The number of different ESTs is taken to be the number of different genes. But it is becoming increasingly clear that ESTs may not directly mimic the gene content of a genome. Furthermore, it may be that one gene can generate two or more different kinds of ESTs, thereby overestimating the number of genes. Both groups took precautions to minimise the complications of duplication but both used different methods to do so, as well as using different analytical approaches. However, the third estimate of 30,000 genes, by Jean Weissenbach and colleagues at Genoscope, France, is strikingly similar to that of Ewing and Green.