A recount of human genes ups the number to at least 46,831 | Science News

SUPPORT SCIENCE NEWS

Science News is a nonprofit.

Help us keep you informed.


Rethink

A recount of human genes ups the number to at least 46,831

The new estimate is based on a broader definition of just what a gene is

By
7:00am, September 17, 2018
dna helix illustration

COUNTING ON IT The number of human genes depends on how scientists define a gene.

Sponsor Message

Figuring out how many genes are in the human genetic instruction manual, or genome, isn’t as easy as scientists once thought. The very definition of a gene has changed since the completion of the Human Genome Project more than 15 years ago.

Genes used to be defined as stretches of DNA that contain instructions that are copied into RNA and then turned into proteins. Researchers still don’t entirely agree on how many of these protein-coding genes there are. Estimates range from 19,901 to a new count of 21,306 published August 20 in BMC Biology.

But in the last decade, researchers have learned that not all genes produce proteins. Many scientists have expanded the definition of a gene to include ones that make RNAs that, instead of being turned into proteins, have other functions in the cell.

Numbers of RNA-producing genes (also called noncoding genes) are even more up in the air than protein-coding genes, says Steven Salzberg, a biostatistician at Johns Hopkins University who headed the new count. His team has already found more of these RNA genes — 25,525, including 18,484 long noncoding RNA, or lncRNA genes (SN: 12/17/11, p. 22) — than protein-coding ones, and his count doesn’t include microRNAs and other recently discovered small RNAs.

Even without the small RNAs, Salzberg’s new total of human genes comes to at least 46,831. Other scientists have debated the estimate, and Salzberg says, “I will not be surprised if 10 years from now, we still don’t have an agreed-upon number.”

Citations

S. L. Salzberg. Open questions: How many genes do we have? BMC Biology. Vol. 16, August 20, 2018. doi: 10.1186/s12915-018-0564-x

Further Reading

T.H. Saey. More than a chicken, fewer than a grape. Science News. Vol. 178, November 6, 2010, p. 5.

T.H. Saey. Missing lincs. Science News. Vol. 180, December 17, 2011, p. 22.

M. Pertea et al. Thousands of large-scale RNA sequencing experiments yield a comprehensive new human gene list and reveal extensive transcriptional noise. bioRxiv.org May 29, 2018. doi: 10.1101/332825

Get Science News headlines by e-mail.

More from Science News

From the Nature Index Paid Content