So far, the highlight of the project has been mapping certain points in the genome that cause diseases
By Yanai Ofran, the "Eretz"
The list of successes already includes several dozen bacteria, yeast, a worm, a plant and a half, a fly, a human, and three quarters of a mouse. Still, molecular biologists' frantic race to crack genomes continues to mark new targets. This week, for example, the banana genome project was launched, and the hand is tipped.
But on the sidelines of this celebration, the voices of researchers are also heard who wonder if this whole business is even worthwhile, and if the billions of dollars invested in deciphering the sequence of bases that make up the genomes were used wisely. More than five months have passed since the dramatic announcement of the completion of the decoding of the human genome, and in the meantime even the most vigorous advocates admit that the project has mostly provided questions.
Therefore, both the leaders of the genome project and the handful of opponents are now debating what the next step should be. Where should genetic research go now? One of the solutions was presented at a gathering of geneticists last week. The heads of the Human Genome Project announced there the launch of the next project: an improved version of the Genome Project.
The new project aims to re-read the human genome, this time in a different way, which might make it possible to bring some order to the mess.
Three decades have passed since the invention of the method for deciphering the sequence of nucleotides, the building blocks that make up DNA, and yet no one still knows how to read these boring sequences of letters. Thus, for example, it turned out that only two percent of the genome are genes, that is, instructions for the production of proteins. What is written in the remaining 98 percent? still not clear.
Still, in the XNUMXs, several molecular biologists initiated an ambitious project designed to determine the exact sequence of all three billion building blocks that make up the human genome. The hope was that a complete picture of the structure of the genome would provide a complete understanding of biology. The human genome project, they hoped, would make it possible to understand what causes various diseases, and how they can be cured. The highlight of the project was the mapping of certain points in the genome that many researchers believe are the ones that cause diseases.
The genomes of all humans are very similar. There are very few points where there can be differences between the genomes of different people. The leaders of the genome project focused on those points, which make up less than half of the genome. They assumed that a mapping of these points, which are called branches, English acronym for Single Nucleotide Polymorphism (Polymorphism Single Nucleotide) could explain the differences between humans. A simple genetic test, they hoped, could reveal whether a particular person carries a particular Snip. Then it will be possible to determine, for example, a person's chances of getting breast cancer, or of responding well to a certain drug.
But some scientists claim that focusing on branches is wrong. Those who try to map the branches assume that the point differences are the main thing. But it is possible that the genome consists of long "sentences" - sequences of several tens of thousands of nucleotides - and not a collection of dots. The differences between people, claim the adherents of this method, do not depend on a single branch, but on the exact pattern of the branches throughout the "sentence".
To find out if a certain person carries a certain genetic trait, you need to find the sentence relevant to that trait, and read the whole thing. Geneticists call such sentences haplotypes. Mapping the genome by focusing on branches does not allow researchers to discover the haplotypes that make up the genome. That is why the leaders of the genome project announced last week that they will devote the next few years to mapping the human holotypes.
The temporary name of the project is the "Human Haplotype Map Project", but even Francis Collins, the somewhat formidable scientist who heads the American National Human Genome Research Institute, admits that with such a name it will be difficult to recreate the enthusiasm of the first genome project. Sexier names, he hinted at the conference, would be welcome.
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