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Human Gene Count Slashed

jd writes "The estimate for the number of genes in human genetic code has been savagely revised downwards. The new estimate, of between 20,000 to 25,000 genes is marginally less than the 27,000 for the Arabidopsis, a flowering plant in the mustard family. Earlier estimates had placed the number of genes at around 44,000 - or even as high as 100,000. Eric Lander of the Broad Institute in Cambridge, Massachusetts is quoted in the CNN story as saying that the number of genes isn't as crucial as how they are used." Read on for more, below.

jd continues: "This has the potential for making life extremely interesting for genetic engineers, given that both individual genes and interactions between genes must be proportionately more complex, in order to get the same level of complexity out. Half the number of genes equates to twice the information encoded in forms other than discrete physical blocks of code.

There is no mention in the article of a story running in 2002 of genetic therapies unexpectedly causing cancer, although if you now factor in the increased complexity of interactions, it is possible that such side-effects can be better understood and therefore prevented. The new estimates, therefore, are more than just idle curiosity but have the potential for impacting how the science is approached."

25 of 504 comments (clear)

  1. Ah by Anonymous Coward · · Score: 5, Funny

    Finally scientific proof that it's not the size that matters, it's how you use it.

    1. Re:Ah by anonymous+cowherd+(m · · Score: 5, Interesting

      Note that even with "only" 20K genes, this still gives us nearly 400M subsets of 2 individual genes to ponder. The complexity of the human organism is not surprising. In fact, it would be surprising if it were not so complex.

      --
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  2. genes, not genomes by Anonymous Coward · · Score: 5, Informative

    It is the number of genes that has been revised down. The genome is the complete set of DNA and contains all the genes.

    1. Re:genes, not genomes by Anonymous Coward · · Score: 5, Interesting

      This is particularly interesting because with less genes then there are less genes that can interact with each other (I'm not talking about major/minor genes). As scientists are learning, the inhibition and activation of genes is alot more complicated than expected. With less genes, it means that the methods such as histone inhibition or non-genetic micro-RNA are more significant. Of course, it may also mean that DNA isn't the holy grail of biology, like we all thought (instead it is a complex interaction between micro-RNA and DNA).

    2. Re:genes, not genomes by delco · · Score: 5, Interesting

      DNA isn't the holy grail of biology, like we all thought (instead it is a complex interaction between micro-RNA and DNA).

      Interesting. I'd go out on a limb and say it was the process of translation or even protein folding that is the actual holy grail.

      There are some camps that believe that the DNA->mRNA interaction (aka transcription) is less complex and more predictable than the mRNA->Protein interaction (aka translation). If my memory serves me well, the process of transcription usually produces a fairly good "copy" of the DNA sequence, while translation seems to have a few unknowns in how he sequence is transformed into AA chains. And then the way in which the proteins fold, and hence gain their function is still up for grabs.

  3. enough... by micronix1 · · Score: 5, Funny

    25,000 genes will be enough for everyone. - 2004

  4. great, we've been demoted by nomadic · · Score: 4, Funny

    The new estimate, of between 20,000 to 25,000 genomes is marginally less than the 27,000 for the Arabidopsis, a flowering plant in the mustard family.

    Damn elitist mustard, looking down on us.

    1. Re:great, we've been demoted by sik0fewl · · Score: 5, Funny

      I, for one, welcome our new Arabidopsis overlords.

      --
      I remember when legal used to mean lawful, now it means some kind of loophole. - Leo Kessler
  5. Great, more downsizing... by DLR · · Score: 5, Funny

    Where'd they off-shore the genes to?

    --
    "Like fire and fusion, government is a dangerous servant and a terrible master."~RAH
  6. Not only that... by FiReaNGeL · · Score: 4, Interesting

    According to scientists, we gained 1000 genes compared to rodents when we diverged from them 75 millions years ago. And we 'lost' 33 genes compared to them (they have a functional copy, we have a nonfunctional pseudogene; it's still there, only not working - stop codons, etc).

    The "we must have more gene than (insert stupid animal or plant here)" is funny. Our superiority complex at its best.

    Read about the whole thing (with more links) on my blog (see sig)

  7. Re:Complexity for smaller? by oddwick11 · · Score: 5, Informative

    Gauging the complexity is difficult, given there are a number of factors not currently understood, particularly the importance of non-coding RNA, which accounts for 98% of the genome. In the past, the information content of these regions was thought to be low, but this attitude is changing. As knowledge of the genome increases, the estimated number of genes drops, and more information emphasis is put on non-coding portions of the genome.

    Evaluating the function of ncRNA is difficult because as of yet there are no statistically significant markers for them. Given the release today, and trends of late, more and more attention will be put on trying to decipher the utility of "junk" DNA.

  8. Re:The Scariest Part of the Article... by larley · · Score: 5, Interesting

    Well, technically, you CAN buy genes. There are quite a few companies that sell pre-sequenced genes. In fact, the entire genomes of several organisms are available in varying amounts ligated into Bacterial Artificial Chromosomes (BACs) and plasmids. An interesting link is http://www.arabidopsis.org/ - There's a lot of information on Arabidopsis, where they keep a database of the entire Arabidopsis genome as well as many freely-available tools for its analysis.

  9. No one knows the answer... by enderwig · · Score: 5, Informative

    to how many genomes are in a single human genome. However, speaking about genes in a genome, as the article states, this "correction" only counts those genes that make some discernable protein product. The number misses the number of open reading frames (ORF) that may not encode a protein at all, but a regulatory or enzymatic RNA. Probably, the next big project in life/medical research, after the big proteomics initiatives, will be the study of non-protein encoding ORFs. This problem is very tough to crack since 1) these RNA's do not have a common sequence element like "normal" messenger RNAs, 2) may be as short as 15 base pair (LIN12(?) in C. elegans), and 3) there are MANY, MANY possible ORFs in the genome.

    Are these technically genes? They are regulated. They have a function. They are transcribed. The only thing different from the standard definition of a gene is that the RNA is not translated into protein.

    In addition to multiple protein products from one "gene" as the article states, regulation of the gene may also be much more complex compared to "lower" organism. For example, the gene expression profile of the malarial parasite Plasmodium falciparum suggests very limited regulation. Basically, it looks like a linear progression with very limit amount of response. So, temporal and spatial regulation makes even multiple product genes seem to like a larger cohort of genes. Take the daughterless gene in Drosophila. It is used very early in embryonic development to control sexual differentiation. However, later, the gene product is used in neuronal differentiation. So, for the fly, sex is literally on the brain.

  10. Re:People vs. Flowers by larley · · Score: 5, Informative

    The thing is, we've had the arabidopsis genome sequenced for a while now. And because the organism has a lower degree of complexity it is a lot easier to study in many ways. I don't know if I'd necessarily say that there is more study being done on humans than on Arabidopsis - In fact, I highly doubt it.

    We have a much clearer idea of most of the inner workings of that lowly little mustard plant than of our own. It's a matter of understanding the simple stuff and then working our way up. Like with the nematode C. elegans -- we know more information about that than you could possibly imagine. We know how many cells it has at every stage of its life and what they are doing. We have its genome sequenced. And from all of this information we have learned a lot about the inner workings of our cells as well. You find a lot of homologies between organisms.

    In fact, if you examine the RNA polymerases of humans, bacteria and archaea you would find that ours are much closer to archaea (the most ancient of ancient organisms still around) than to bacteria.

    So looking at these organisms that have been around since the beginning of life, we can learn about the development of our genomes and by examining their functions we can learn much about how ours work. Even if we do have our entire genome sequenced, that doesn't mean we know what it all does.

  11. Re:Complexity for smaller? by afidel · · Score: 5, Informative

    Actually last months Scientific American had a good article on this. Basically we are finding that what we once thought was junk (non coding areas and RNA coding areas which do not code for proteins) is probably some of the more important aspects of the nucleus. I quote:

    "But investigators have since sequenced the genomes of diverse species, and it has become abundantly clear that to correlation between numbers of conventional genes and complexity truly is poor. The simple nematode worm Caenorhabditis elegans (made up of only about 1,000 cells) has about 19,000 protein-coding genes, almost 50 percent more than insects (13,500) and nearly as many as humans (around 25,000). Conversely, the relation between the amount of nonprotein-coding DNA sequences and organism complexity is more sonsistent.

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  12. Re:That's genes! Not genomes! by Anonymous Coward · · Score: 5, Informative

    Only one? Ahem: Mitochondrial genome; Nuclear genome.

    As a mitochondrial researcher, I resent the most important organelle of the cell being overlooked or lumped in together with the nucleus here!

    So I would say two genomes :)

  13. Gene Therapy by Camel+Pilot · · Score: 5, Insightful
    Why are we not directing our massive GNP towards scientific exploration such as studying genetic therapies to cure the rift raft of ailiments that curse mankind instead of fighting petty wars against a minor enemy "aka terrorist".

    Let look at that stats:

    Terrorist kill ~ 3000 people in 2001 and it becomes a focus of the US nation. While:

    Breast cancer kills > 40,000 / year

    Prostate cancer kills > 30,000 / year

    Diabetes kills > 70,000 / year

    The numbers world wide of course are much larger.

    Yeah OT I know but these kind of discoveries convince me our priorities are misplaced.

  14. Frightening headline by Pan+T.+Hose · · Score: 4, Funny

    I've read the headline as "Human Genome Slashdotted" and I shouted: "Dear God, we're doomed!" My God, what an embarrassment... I need sleep.

    --
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    Pan Tarhei Hosé, PhD.
    "Homo sum et cogito ergo odi profanum vulgus et libido."
  15. Re:Complexity for smaller? by metlin · · Score: 4, Interesting

    I'm not sure how that is.

    "We just have to get used to the fact that we don't have many more genes than a worm," Rubin said.

    So how can humans be so complex with relatively few genes?


    Seems to me like the instruction sets are the same, while the coding complexity varies?

  16. Re:Complexity for smaller? by Nutty_Irishman · · Score: 4, Insightful

    On the contrary, the complexity now increases. There are many genes that act in completely differen't roles depending on the cell type (nerve, epidermal, etc.). So a common language changes from cell type to cell type-- if one would even call it a common language. There is a large part of Bioinformatics/Computational Biology that deals with trying to determine interaction networks between genes. It's very complex, and difficult to deal with.

    With less genes we then expect to have a larger amount of downstream interactions between other genes. It might seem that with less genes then we have less to worry about, but we have already speculated for a long time that gene regulatory networks are complex.

    To use an analogy (for all you computer geeks), it's like a programmer trying to read poorly modularized code. When you have no idea what class is doing what, and how they interact with other classes (as every class has multiple roles and talks to multiple other classes) then it is difficult to understand why the program behaves the way it does. If the program had many classes that were well modularized and designed with very distinct roles, then it would be easier to understand why things work the way they do.

    With less genes and increased complexity we have an even more difficult task. It also highlights some of the reasons on why microarray analysis has not done what we expected it to do. Increasing the complexity and dependency between genes means that we probably are going to take a longer time understanding and extrapolating information from all these networks (which means more job security for me :) ).

  17. Genes -- Proteins by oddwick11 · · Score: 5, Interesting

    An often unknown fact is that a single gene can code for thousands of different proteins. Protein regulation can occur in a variety of way, one of which is through "junk" DNA.

    Currently little is known on the exact mechanism, which is a huge impediment to proteomics. As the phenomenon is elucidated, expect to see a lot more useful information coming out of genome projects.

    Computationally predicting the 3-D structure and function of a gene is far more important than you probably realize. Reaching this point will revolutionize almost every aspect of your life, from pharmaceuticals, to nutrition, to silico-neural interfaces.

  18. Spoiler alert by vandelais · · Score: 4, Funny

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    1. Re:Spoiler alert by servognome · · Score: 4, Funny

      It's a gene sequence?
      I thought it was one of those pictures that if you stare at it right turns 3D... stupid waste of 4 hours!

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    2. Re:Spoiler alert by addaon · · Score: 5, Funny

      He only posted a few lines of it, but it reproduced.

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      I've had this sig for three days.
  19. Re:Complexity for smaller? by avsed · · Score: 5, Interesting

    Actually, that's a bad analogy, since modern assembly possesses a significantly richer grammar than C. However, it is correct to say that the interactions between language elements (instructions) in ASM are very much simpler than in C.
    More on topic: Why are people surprised that millions of years of evolution has resulted in a high entropy encoding "format" (the genome) whose consituent elements are multipurpose and have complex interactions with each other? An animal is more evolved (has a history of more complex environmental interactions) than a plant, so why shouldn't its genome be less redundant / contain more entropy? Comparisons of number of genes are (to return to the computing analogy) like comparing two processors based on their physical size.
    D.