Number of Human Genes Questioned

This is the VOA Special English SCIENCE REPORT.

Scientists are questioning a widely reported finding from the first detailed study of the human gene map. The scientists dispute the finding that humans have only about thirty-thousand genes.

The new report suggests the true number could be much greater. The Genomics Institute of the Novartis Research Foundation in San Diego, California prepared the report. It was published in Cell magazine.

Other scientists have long argued about the number of human genes. Some believe that humans have more than one-hundred-thousand genes.

The issue seemed to be settled last February. That is when two competing teams of scientists published their efforts to map the position of every human gene. A private American company called Celera Genomics published one of the genetic maps. An international group called the Human Genome Project prepared the other. Each group of scientists estimated that humans have about thirty-thousand genes. That is about two times as many genes as some insects.

That number came as a surprise to some people. They wondered how an organism as complex as a human could have so few genes. It is important for scientists to identify every human gene in order to understand how cells work and what causes disease. Some scientists believed the small number of genes was good news. It meant it would be easier to identify all the genes and understand how they work.

In the new study, the Novartis scientists compared the two groups of human genes from the two genetic maps. They found that the two groups of scientists had identified two different sets of genes. Only about half the genes are common to both groups. The Novartis scientists say this means the number of human genes may be about forty-thousand.

The director of the Human Genome Project, Francis Collins, said he would not be surprised if humans were found to have more than thirty-thousand genes. Celera's President, Craig Venter, notes that the process of discovering the real number is not simple. He said many of the genes noted in his company's study had not been confirmed.

The real number of human genes may not be known any time soon. Scientists say it probably will take years before we have a list of the genes that control human biology.

This VOA Special English SCIENCE REPORT was written by George Grow.