How Many Human Genes Are There?

Steven Salzberg
Hurvitz Professor of Computer Science and Director, Center for Bioinformatics and Computational Biology, University of Maryland

2274th Meeting Abstract
Friday, October 29, 2010 at 8:15 PM

Steven Salzberg


Ever since the discovery of the genetic code in the early 1960's, scientists have been working to identify all the genes in the human genome. At the same time, many scientists have been looking, thus far without much success, for genes that make humans special compared to other species. As these efforts have progressed and DNA sequencing technology improved, initial estimates of the number of human genes have been revised, and over time have steadily decreased. Many scientists expected this question to be finally answered by determining the complete DNA sequence of the human genome. But the information obtained at completion of the sequence in 2001 did not, as it turned out, allow scientists to identify all the genes or determine how many there are. Since then, estimates of the gene count have continued to fluctuate, both up and down. And comparisons of the sequences of the human genome with the genomes of other species seems to show that nothing about the human gene count is exceptional. In fact, while some simpler organisms have fewer genes, other “lower" species have considerable larger genomes and more genes than humans. This talk will review the history of efforts to identify human genes and explain the evidence for our own current best estimate of 22,333 genes.

About the Author:

Steven Salzberg is Horvitz Professor of Computer Science and Director, Center for Bioinformatics and Computational Biology, University of Maryland, College Park. He works on better ways of finding genes, assembling genomes, and understanding evolution. He has developed open source software for DNA sequence analysis that has been used globally by thousands of scientists. He has contributed to many seminal sequencing projects, including the Human Genome Project and the Bacillus anthracis sequencing project after the anthrax attacks in 2001. He also co-founded the Influenza Genome Sequencing Project, which sequenced thousands of viruses. His work has been featured in the national press including the New York Times, the Wall St. Journal, the Washington Post, and National Public Radio.

Dr. Salzberg received his B.A., M.S., and M.Phil. degrees from Yale University, and his Ph.D. in Computer Science from Harvard University. He joined Johns Hopkins University as an Assistant Professor in 1989, and moved to The Institute for Genomic Research (TIGR) in 1997. He joined the Computer Science Department at the University of Maryland in 2005, where he now holds joint appointments in Genetics and Bioengineering. He has published over 175 scientific papers and two books. He is a Fellow of the American Association for the Advancement of Science and a past member of the Board of Scientific Counselors of the National Center for Biotechnology Information at NIH. For more information visit his website at or his science blog at

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