100,000, 40,000, 25,000, 19,000 – the shrinking human genome…
For sure many of you remember old textbooks, in which the total number of genes in the human genome was estimated around 40,000 to 100,000. After the human genome was sequenced this number shrunk to 26,000 – 40,000 genes. The 19th GENCODE release further reduced this number to 20,318 protein-coding genes. But not enough a recent study suggested that the actual number of protein-coding genes in humans lies around 19,000.
This astonishing result could be obtained by analyzing the data derived from seven large MS-based proteomics studies from more than 50 human tissues.
But the shrinking number of genes is not the only remarkable results – find below the most important results from this study as described in a recent ScienceDaily blog post:
- Close to 12 000 human genes could be unambiguously identified
- Despite high coverage from seven analyses, 40% of the peptides from the human gene set could not be detected; Possible reasons:
- Thousands of genes annotated in the human genome did not appear in the proteomics analysis.
- Apparently 1,700 genes that were previously thought to produce proteins most certainly don’t
- Another hypothesis is that more than 90% of human genes produce proteins originating in metazoans or multicellular organisms living hundreds of millions of years ago
- The difference between humans and primates at the gene and protein level is very small
- “The number of new genes that separate humans from mice may even be fewer than 10”
- Physiological and developmental differences between primates are more likely caused by gene regulation than by differences in the basic functions of proteins in question
Alfonso Valencia, the main researcher behind this project states that “the human genome is best annotated, but we still believe that 1,700 genes may have to be re-annotated”.
According to Alfonso Valencia these results may redefine the entire mapping of the human genome.