Last year, Chinese researcher He Jiankui shocked the scientific community. He had artificially conceived genetically manipulated children. Now a study confirms: They have a significantly shorter life expectancy.
Image: Imago/Science Photo Library
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At the end of November 2018, Chinese biophysicist He Jiankui reported at a symposium in Hong Kong that he had conceived two children through artificial insemination. The big news: he had manipulated their genetic material with the help of the CRISPR/Cas9 "genetic scissors" before implanting the embryos.
This is probably the world's first case in which the human germline has been genetically manipulated. Changes like this will be passed on to future generations.
Ethicists and experts from a wide range of disciplines sharply criticized He's approach at the time: They said he had created a dangerous precedent and committed a grave ethical breach. Later, the Chinese government issued strict rules preventing future attempts at germline manipulation.
Moreover, there was no medical need for the genome editing and it was completely unclear whether the children or their possible offspring would be hit with undesirable health consequences later in life.
Now a study by Xinzhu Wei and Rasmus Nielsen from the University of Berkeley in the US state of California confirms the fears of critics at the time: People who have a comparable natural genetic modification die much earlier on average than people without it. The study was published in the journal Nature Medicine.
The scientific community was shocked when they learned about He's genome editing experiment. Image: Imago/Zuma Press
Immunity to the HI virus by removal of a gene
He Jiankui had justified his germline intervention with the fact that the father of the children carried the HI virus (HIV), which triggers the immunodeficiency disease AIDS. He claims that his intention was to make the children immune to HIV through the genome editing.
And this is how He proceeded: HIV uses a cell protein encoded by a specific gene called CCR5 to attack cells of the immune system. Using the CRISPR-Cas9 gene scissors, the biophysicist removed the CCR5 gene from the genome before implanting the embryo in order to prevent a potential infection of the children with HIV.
CCR5 is the most important gateway for HIV, but there are others, too, that were not closed by He's genetic manipulation.
Some people are immune by nature
The biophysicist argued that there are many people who naturally do not carry a CCR5 gene in their genome. There are an estimated 100,000 people with this mutation, called Delta 32, in the world.
The mutation also makes them immune to the HI virus. According to He, these people are otherwise healthy.
But this appears to not be entirely true, as the study from Berkeley now suggests. Xinzhu Wei and Rasmus Nielsen have statistically searched the world's largest human gene database, the UK Biobank, to find out whether other health risks are associated with the absence of the CCR5 gene or with the natural mutation Delta 32.
Small changes in genes can lead to unpredictable health issuesImage: Max-Planck-Institut
The UK Biobank lists the gene variants (genotype) and the related health and other physical characteristics (phenotype) of more than 400,000 people.
The researchers had three genotypes in mind: People who had the mutation Delta 32 twice, people who had Delta 32 once and the CCR5 gene once and people who had the CCR5 gene twice. The babies whose genome He edited would fall into the first group with two Delta 32 mutations.
HIV immunity paid for by higher flu mortality risk
The researchers found that people with a twofold Delta 32 mutation, who completely lack CCR5, have a 21 percent lower probability of reaching 76 years of age than those with no or only one Delta 32 mutation.
This is probably due to the fact that the CCR5 gene is important for human health. Removing it may make patients susceptible to other diseases. It is a functional protein that has an effect on the organism, Nielsen stressed in a Berkeley University statement.
A previous study had shown that people without this gene die four times more often from influenza than people carrying CCR5.
Nielsen concludes that a mutation that destroys the protein is probably not good for humans or animals. And Wei agrees that the CRISPR technology is far too dangerous to currently be used for germline processing.
Islands and their surrounding marine areas are the focus of this year's International Day for Biological Diversity. Islands constitute unique ecosystems that often comprise many endemic plant and animal species.
Image: John Weller/AP/dapd
Focus on islands
Islands and their surrounding marine areas are the focus of this year's International Day for Biological Diversity on May 22. Islands are unique ecosystems with plant and animal species that are often found nowhere else on Earth. They are also home to one-tenth of the world's human population and are increasingly coming under population and climate pressure.
Image: picture-alliance/DUMONT Bildarchiv
Under pressure
Of the 724 recorded animal extinctions in the last 400 years, about half were island species, according to the UN's Convention on Biological Diversity. Over the past century, island biodiversity has been subject to intense pressure from invasive species, habitat change and over-exploitation, as well as, increasingly, from climate change and pollution caused by humans.
Image: AP
Invasive species
The brown tree snake is infamous for being the invasive species that devastated the majority of the native animal population on the Pacific island of Guam. With no natural predators, its accidental introduction is thought to have caused the extinction of 12 native bird species. It has also negatively affected vegetative species diversity and even affected the economy, experts say.
Image: public domain
Pilot project
For three decades, conservationists have been working to rebuild the original ecosystem of Mauritius on the tiny island of Ile aux Aigrettes. They've now managed to eradicate most foreign animals like rats, rabbits and goats, and have replanted forests. In some cases authorities replaced extinct animals, like the original giant tortoise, with a similar animal to maintain the ecosystem's balance.
Image: picture-alliance/dpa
Biodiversity hotspot: Madagascar
A biodiversity hotspot is a region under threat from human activities which also has a high level of endemic species. While hotspots are spread all over the world, the most are in forest areas and located in the tropics. Madagascar's dry deciduous forests and lowland rainforests have complex ecosystems, but many of the forests have been almost entirely destroyed by overgrazing and deforestation.
Image: Photoshot/Balance/picture alliance
New temperatures, new residents
Over the last 50 years, conditions on the German island of Heligoland have dramatically changed. Scientists at the Biological Institute Heligoland say the average water temperature has increased by 1.7 degrees Celsius in half a century. There are now around 60 species that were not present in local waters before, including types of hermit crabs, sea slugs, bristle worms and jellyfish.
Image: picture-alliance/dpa
Norfolk Island’s lost rainforest
Before European colonization, Norfolk Island was once covered with subtropical rainforest. The Norfolk Island palm made up part of the forest undergrowth, while the famous Norfolk Island pine formed the canopy. Now, only one small area of the original rainforest remains on the island, which has now been declared a national park. The forest remains infested with several introduced plants.
Image: public domain
Mountain paradise
Taiwan is home to a huge range of plant and animal species. That's partly due to the various natural landscapes that stretch between the coastal regions and high mountain ranges. Most of the 17 bird types that are unique to Taiwan live in the high mountain ranges, shielded from the rapid urban development in the country below. One of them, the Mikado pheasant, lives only above 1,800 meters.
Image: CC/Snowyowls
Hawaii’s monk seals
The Hawaiian monk seal is the only native seal left in Hawaii and is highly endangered. The small population of about 1,100 is threatened by human encroachment and fishing, low levels of genetic variation, and marine debris. The National Marine Fisheries Service in the United States has had a Hawaiian Monk Seal Recovery plan in place since 1983, but numbers are still dangerously low.
Image: picture-alliance/Wildlife
Part of a bigger plan
As part of the UN's Decade on Biodiversity, countries are required to implement the 20 so-called "Aichi Biodiversity Targets." The targets are meant to reduce loss of biodiversity worldwide. A workshop for small developing island states to better tackle invasive alien species is due to be held in Montreal in June. It will examine one how island ecosystems can be better protected.
