Question: what does it mean 155 new genes have been identified?

Zoe Vance answered on 14 Mar 2024:

A gene is basically just a part of your DNA that gives instructions to make something, usually a protein. We usually think of DNA as a big string of letters and some stretches of letters give your cells this information. The human genome (all our DNA) is made up of about 3 billion letters so it isn’t necessarily easy to search for genes, and some of them are missed. This can be because the ‘assembly’ of the genome wasn’t complete, so we didn’t have every single letter to search against (some parts of the genome are harder to put together than others – think of it like putting together a jigsaw with a lot of identical pieces!). Sometimes the genes themselves are also hard to find because they don’t look like other genes or get missed with our standard gene-finding methods. When we improve the quality of the genome we’re looking at or try new methods sometimes we find genes that we didn’t know about previously.

To give more specific info for the study I *think* you’re talking about, the 155 genes were very small and encoded ‘microproteins’. These kind of genes get missed with standard methods because when we’re trying to identify areas of DNA that might be genes we don’t tend to prioritise very short candidates to look into further. One of the ways we try to identify genes is by looking for “ORFs” (open reading frames), stretches of DNA that are between a start codon (the letters ATG) and a stop codon (TGA, TAA or TAG). These sequences of letters signal the start and end of the information that creates a protein, but because there are only 4 options for DNA letters (A,T,G,C) they also happen in the genome just by random chance so it would be very time consuming to look at every single ORF there is. So that’s why those specific ones were only found when we used some additional information.