SEP 06, 2018 08:05 PM PDT

The Human Genome may Contain 20% Fewer Genes Than Thought

WRITTEN BY: Carmen Leitch

The human genome was estimated to contain anywhere from 50,000 to 90,000 genes around the year 2000, and that number has been steadily revised downward. After the human genome was sequenced, it appeared that there were around 20,500 genes. Now, a research team led by scientists at the Spanish National Cancer Research Centre (CNIO) has found that there are probably even fewer genes that code for protein; they estimate that 20 percent of genes that have been classified as coding may actually be non-coding. This work, reported in Nucleic Acids Research, may have serious implications for biomedical research.

Image credit: Pixabay

It has been challenging to determine the exact number of coding genes; the human genome is complex, and there are thousands of genes. The team started by carefully comparing proteins that are expressed in cells, called the proteome, in the GENCODE/Ensembl, RefSeq and UniProtKB reference databases. Of 22,210 coding genes listed, only 19,446 of the genes were found in all three databases. 

The team focused on the 2,764 genes that were only found in one or two of the references; after looking at annotations and experimental evidence, they found that nearly all of them were predicted to be pseudogenes (which have unknown functions but seem to be non-coding), or other genes that don't encode for protein. 

The team also identified 1,470 coding genes in the databases that don’t evolve like other genes, and probably aren't protein-coding. The researchers concluded that 4,234 genes in all are non-coding genes.

"We have been able to analyze many of these genes in detail," explained Michael Tress of the CNIO Bioinformatics Unit "and more than 300 genes have already been reclassified as non-coding." The results are already being included in the new annotations of the human genome by the GENCODE international consortium, of which the CNIO researchers are part.

More work remains before we know everything about the human genome. "Our evidence suggests that humans may only have 19,000 coding genes, but we still do not know which 19,000 genes are,” noted first author Federico Abascal of the Wellcome Trust Sanger Institute in the United Kingdom.

The study may cause some serious ripples in some research. "Surprisingly, some of these unusual genes have been well studied and have more than 100 scientific publications based on the assumption that the gene produces a protein,” added David Juan of the Pompeu Fabra University.

You can learn more about what we do know from the following video, by Harvard University.

Sources: AAAS/Eurekalert! via CINO, Nature Genetics, Nucleic Acid Research

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
NOV 15, 2018
Genetics & Genomics
NOV 15, 2018
How Technology can Help Feed the World
As the world's population grows, plant scientists know that the race is on to develop technologies that will help feed everyone....
DEC 11, 2018
Genetics & Genomics
DEC 11, 2018
Dust with High Levels of Triclosan has More Antibiotic Resistance Genes
Researchers have found that some dust contains high amounts of a common antimicrobial agent called triclosan....
DEC 30, 2018
Genetics & Genomics
DEC 30, 2018
An Improved Alzheimer's Model Adds Genetic Diversity
Researchers created a mouse model of Alzheimer's disease that has more in common with the human disease than current models....
JAN 08, 2019
Videos
JAN 08, 2019
Nature v Nurture - Do Our Genes Determine Who We Are?
As humans have learned more about our genome, we have sought to understand more about how much our genes influence who we are....
JAN 18, 2019
Genetics & Genomics
JAN 18, 2019
Insight Into the Molecular Basis of Obesity
Obesity is a major health problem around the world, impacting adults and an estimated 41 million children....
JAN 20, 2019
Genetics & Genomics
JAN 20, 2019
Identifying Genetic Regions That Influence Lifespan
It may one day be possible to predict how long a person will live by looking at a few regions of a person's genome....
Loading Comments...