NEW YORK, July 11 – Researchers at the Joint Genome Institute have determined that the human genome contains about 30,000 genes, a finding that supports previously published estimates and could help settle a longstanding debate among genomic scientists.
Based on a comparison of human chromosome 19 with similar sections of mouse DNA, the JGI researchers estimated that the human genome contains far fewer genes than some academic and corporate researchers had previously thought.
Companies such as Human Genome Sciences and Incyte were previously taken to task for claiming that there are more than 100,000 genes in the human genome just as researchers were estimating a more modest 30,000 – 40,000 genes.
Incyte has defended its statements as well as its add campaign, which until several months ago promised a product that offered access to 120,000 genes, by saying that it was talking about transcripts rather than actual genes. Human Genome Sciences was not immediately available to comment.
The JGI research, which was conducted by a team led by biomedical scientist Lisa Stubbs of Lawrence Livermore National Laboratory, details its findings in this week’s edition of Science.
"There had been speculation that aligning the human and mouse DNA sequence might reveal many more genes," said Stubbs in a statement. “However, if chromosome 19 is indicative of other chromosomes, the estimate of 30,000 genes is fairly accurate."
Before the comparison of human and mouse DNA, researchers had thought that human chromosome 19 had about 1,100 genes. With the comparative analysis, about 1,200 were found, Stubbs said.
Through their study, researchers at the Joint Genome Institute team found apparent additional sections of more than 300 human genes, confirmed the existence of other computer-predicted genes, and provided evidence to discard other gene predictions, Stubbs said.
In the study, the researchers found that about 90 percent of the human genes in chromosome 19 were also located in similar sections of mouse DNA, Stubbs said.
The approximately 10 percent of human or mouse genes that are unique to each other are the type of genes that tend to duplicate, or make extra copies, over time.
These genes include zinc finger genes, which produce proteins that control the activity levels of other genes; olfactory receptor genes, which are responsible for the sense of smell; and the genes encoding receptors for pheromones, which serve as a chemical attractant for mating and other social behavior.
Mouse and human DNA contain different complements of these types of genes because active duplications have created new genes specifically in primates or rodents, the researchers said.