Welcome to the Golden Age of Genetics
There has been a remarkable experiment that might, in time, offer treatment of the hereditary aspect of many different and important diseases.
For most of my professional life I regarded the human genome as unalterable in any living person's lifetime. This is now changing. In my book, The Mysterious World of the Human Genome, I suggested that we are on the threshold of a "golden age" of genetics and genomics. It hasn't come about through any single breakthrough but through a series of breakthroughs in understanding.
Most important of these was solving the various mysteries of our human genome, in which only 1.5% of our total DNA codes for proteins. So what is the huge remainder doing? How come almost half of our DNA is either directly derived from the genomes of retroviruses, or somehow linked with and probably also derived from more ancient viruses? We are still working on this but now we know that the viral component is not junk, but is playing important roles in our genetics, biochemistry and physiology. Indeed, until three or four years ago there was yet another huge chunk of our DNA that had an entirely unknown function. But now we know this is part of the mysterious epigenetic system - the master controllers of how the entire system works.
So fathoming how all of this works as an extraordinary and integrated system was a key step.
This enabled us to see how the genome of a single fertilised cell, or a very early embryo, might be altered, so the alteration could enter every living cell of the subsequent individual that developed from that fertilised cell or embryo. But how could any technique change the genome of a fully developed human being, with all of his or her complexity of cells, tissues and organs?
In fact several breakthroughs are now making important inroads into this seemingly impossible quest. One such breakthrough is that viruses can have their genomes edited so they target a specific cell, tissue or organ. Another is the introduction of techniques, such as CRISPR - I won't bother explaining what the acronym stands for - which can enter the genome of the targeted cell, tissue or organ and cut out a tiny fragment of damaged or mutated DNA, leaving the cells own DNA repair mechanisms to close the gap at the point of the excision.
In recent months American scientists have done exactly this in mice bred to suffer from the human version of a type of muscular dystrophy, known as Duchenne muscular dystrophy. In boys suffering from this sex-linked disease, there is a mutation in the protein called dystrophin, which strengthens muscle fibres. Scientists have injected a virus carrying the CRISPR instructions to cut out the defective portion of the gene in the mice, and it appears to have helped the mice to perform tasks of muscle strength.
Of course this is only a tentative first step. There will be new steps, improvements on the basic methodology, and perhaps soon trials of this, or other gene-altering treatments, of hereditary diseases - we doctors call them "inherited disorders of metabolism". It's no longer speculative. It's going to happen - and soon. We really are entering that golden age I predicted in my book.
For more detail see the first class article by Jocelyn Kaiser in Sciencemagazine.
http://news.sciencemag.org/biology/20...
The Mysterious World of the Human Genome
For most of my professional life I regarded the human genome as unalterable in any living person's lifetime. This is now changing. In my book, The Mysterious World of the Human Genome, I suggested that we are on the threshold of a "golden age" of genetics and genomics. It hasn't come about through any single breakthrough but through a series of breakthroughs in understanding.
Most important of these was solving the various mysteries of our human genome, in which only 1.5% of our total DNA codes for proteins. So what is the huge remainder doing? How come almost half of our DNA is either directly derived from the genomes of retroviruses, or somehow linked with and probably also derived from more ancient viruses? We are still working on this but now we know that the viral component is not junk, but is playing important roles in our genetics, biochemistry and physiology. Indeed, until three or four years ago there was yet another huge chunk of our DNA that had an entirely unknown function. But now we know this is part of the mysterious epigenetic system - the master controllers of how the entire system works.
So fathoming how all of this works as an extraordinary and integrated system was a key step.
This enabled us to see how the genome of a single fertilised cell, or a very early embryo, might be altered, so the alteration could enter every living cell of the subsequent individual that developed from that fertilised cell or embryo. But how could any technique change the genome of a fully developed human being, with all of his or her complexity of cells, tissues and organs?
In fact several breakthroughs are now making important inroads into this seemingly impossible quest. One such breakthrough is that viruses can have their genomes edited so they target a specific cell, tissue or organ. Another is the introduction of techniques, such as CRISPR - I won't bother explaining what the acronym stands for - which can enter the genome of the targeted cell, tissue or organ and cut out a tiny fragment of damaged or mutated DNA, leaving the cells own DNA repair mechanisms to close the gap at the point of the excision.
In recent months American scientists have done exactly this in mice bred to suffer from the human version of a type of muscular dystrophy, known as Duchenne muscular dystrophy. In boys suffering from this sex-linked disease, there is a mutation in the protein called dystrophin, which strengthens muscle fibres. Scientists have injected a virus carrying the CRISPR instructions to cut out the defective portion of the gene in the mice, and it appears to have helped the mice to perform tasks of muscle strength.
Of course this is only a tentative first step. There will be new steps, improvements on the basic methodology, and perhaps soon trials of this, or other gene-altering treatments, of hereditary diseases - we doctors call them "inherited disorders of metabolism". It's no longer speculative. It's going to happen - and soon. We really are entering that golden age I predicted in my book.
For more detail see the first class article by Jocelyn Kaiser in Sciencemagazine.
http://news.sciencemag.org/biology/20...
The Mysterious World of the Human Genome
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