This is a site-wide search. An organism inherits some genes from each parent and thus the parents pass on certain traits to their offspring. Gene therapy and genetic engineering are two closely related technologies that involve altering the genetic material of organisms. The distinction between the two is based on purpose. Gene therapy seeks to alter genes to correct genetic defects and thus prevent or cure genetic diseases.
Genetic engineering aims to modify the genes to enhance the capabilities of the organism beyond what is normal. Ethical controversy surrounds possible use of the both of these technologies in plants, nonhuman animals, and humans. Particularly with genetic engineering, for instance, one wonders whether it would be proper to tinker with human genes to make people able to outperform the greatest Olympic athletes or much smarter than Einstein.
If genetic engineering is meant in a very broad sense to include any intentional genetic alteration, then it includes gene therapy. Two fundamental kinds of cell are somatic cells and reproductive cells.
Most of the cells in our bodies are somatic — cells that make up organs like skin, liver, heart, lungs, etc. Reproductive cells are sperm cells, egg cells, and cells from very early embryos. Two problems must be confronted when changing genes. The first is what kind of change to make to the gene. The second is how to incorporate that change in all the other cells that are must be changed to achieve a desired effect.
There are several options for what kind of change to make to the gene. Or one could use a chemical to simply turn off a gene and prevent it from acting.
There are also several options for how to spread the genetic change to all the cells that need to be changed. If the altered cell is a reproductive cell, then a few such cells could be changed and the change would reach the other somatic cells as those somatic cells were created as the organism develops. But if the change were made to a somatic cell, changing all the other relevant somatic cells individually like the first would be impractical due to the sheer number of such cells.
The cells of a major organ such as the heart or liver are too numerous to change one-by-one. Instead, to reach such somatic cells a common approach is to use a carrier, or vector, which is a molecule or organism.
A virus, for example, could be used as a vector. The virus would be an innocuous one or changed so as not to cause disease. It would need to be a very specific virus that would infect heart cells, for instance, without infecting and changing all the other cells of the body.
Fat particles and chemicals have also been used as vectors because they can penetrate the cell membrane and move into the cell nucleus with the new genetic material. Companies working on next-generation antibiotics have developed otherwise harmless viruses that find and attack specific strains of bacteria that cause dangerous infections.
Meanwhile, researchers are using gene editing to make pig organs safe to transplant into humans. Gene editing has transformed fundamental research too, allowing scientists to understand precisely how specific genes operate. So how does it work? There are many ways to edit genes, but the breakthrough behind the greatest achievements in recent years is a molecular tool called Crispr-Cas9. When the cell tries to fix the damage, it often makes a hash of it, and effectively disables the gene.
This in itself is useful for turning off harmful genes. But other kinds of repairs are possible. For example, to mend a faulty gene, scientists can cut the mutated DNA and replace it with a healthy strand that is injected alongside the Crispr-Cas9 molecules. Different enzymes can be used instead of Cas9, such as Cpf1, which may help edit DNA more effectively. Remind me what genes are again?
Genes are the biological templates the body uses to make the structural proteins and enzymes needed to build and maintain tissues and organs. They are made up of strands of genetic code, denoted by the letters G, C, T and A. Humans have about 20, genes bundled into 23 pairs of chromosomes all coiled up in the nucleus of nearly every cell in the body. Only about 1. The rest of our DNA is apparently useless. What are all those Gs, Cs, Ts and As? The letters of the genetic code refer to the molecules guanine G , cytosine C , thymine T and adenine A.
It takes a lot of them to make a gene. The gene damaged in cystic fibrosis contains about , base pairs, while the one that is mutated in muscular dystrophy has about 2. Each of us inherits about 60 new mutations from our parents, the majority coming from our father.
Beal says that this could include making strategic chemical modifications to the engineered RNAs that stabilize them, or embedding them in a nanoparticle or virus that can sneak into cells. Packing viruses with the genes that encode all the machinery needed for RNA editing might not be efficient. But some researchers worry that conscripting the natural ADARs into editing specific mRNAs could pull them away from their normal tasks and cause other health problems.
Altering gene expression in one part of the body could affect other parts in unforeseen ways. Bermingham is optimistic about the prospects of RNA editing, but cautious not to get ahead of the biology. Stafforst, T. PubMed Article Google Scholar.
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Research Highlight 12 NOV Article 10 NOV Technology Feature 09 NOV Article 03 NOV The argument stems from research that shows the wild version of the gene that most humans inherit — the kind the babies would have had — actually suppresses the brain's "neuroplasticity", or ability to grow and reorganise itself. Some studies have shown that people who lack a normal CCR5 may recover from strokes more quickly and they reportedly do better in school , while mice without a functional version of this gene have better memories.
However, there are some situations in which rare mutations can spread widely, whether they're useful or not. Take Huntington's disease, a harrowing condition which gradually stops the brain working normally, eventually causing death. It's unusual for a genetic disease in that even if you have one healthy copy of the gene you will still develop it — meaning that you might expect it to eventually die out.
However, at Lake Maracaibo in northwest Venezuela — actually vast, ancient inlet of the Caribbean Sea — there is a higher concentration of people with the disease than anywhere else in the world. There are two reasons that this is thought to have happened. One is the fact that Huntington's disease typically materialises when people are around 40 years old, which is after the age at which most people have children — and consequently, the illness is almost invisible to evolution , which primarily cares if an organism has survived to the age of reproduction.
The second is the Founder Effect , which distorts the distribution of genes in small populations by allowing the unusual genes of the "founders" — early community members — to propagate more widely than they otherwise would. She was a carrier of the deadly mutation that causes it, which she passed on to more than 10 generations of descendants — encompassing more than 14, living people , as of The Founder Effect can distort the frequency of genes in a population, and is thought to have led to the high prevalence of Huntington's at Lake Maracaibo Credit: Getty Images.
In China where it's thought they live, there are currently high rates of internal migration , so it's conceivably less likely that the genes will become embedded. Another possibility is that the genetic mistakes will be located next to a highly beneficial trait on the genome, so that they're inherited together — a situation that allows neutral or harmful mutations to piggyback their way to a higher prevalence than they deserve.
However, Saha points out that it may take many, many generations for any patterns in the distribution of genetic errors to materialise. This is a very big question for us to collectively think about.
There is an obvious solution — though there's no guarantee edited humans would agree to it, and it relies on a person being aware that their reproductive cells have been edited, as may not be the case with those who have undergone somatic editing for an illness that manifests elsewhere in the body.
Rather than allowing any artificial mutations to propagate, we could simply correct them, using the same technique that was used to create them in the first place. Given the how little we know about the functions of certain genes in our current environment, Saha believes we must be extra cautious when making potentially millennia-straddling changes. To decide if an edit is ethical, we might first need to understand what kind of future world it could linger on in.
An earlier version incorrectly referred to He Jiankui by his first name. The article also described the Huntington's mutation as recessive, when it is dominant. Join one million Future fans by liking us on Facebook , or follow us on Twitter or Instagram. If you liked this story, sign up for the weekly bbc. The genetic mistakes that could shape our species.
Share using Email. By Zaria Gorvett. New technologies may have already introduced genetic errors to the human gene pool.
How long will they last?
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