Mouse with two FATHERS could pave way for gay men to have children
For the first time, mice born to two fathers have grown up and produced offspring, scientists in China have revealed.
The researchers at Shanghai Jiao Tong University managed to insert two sperm cells - one from each father - into a mouse egg whose nucleus had been removed.
A gene editing technique was then used to reprogram parts of the sperm DNA to allow an embryo to develop – a process called androgenesis.
The embryo, featuring the genetic material from two fathers, was transferred to a female womb and allowed to grow to term.
Finally, the resulting offspring (male) managed to grow to adulthood and become a parent after mating conventionally with a female.
In their lab experiments, the researchers managed to successfully demonstrate the method twice – birthing two fertile male mice, both with two fathers.
The promising breakthrough could pave the way for two gay men to have a child of their own who can also go on to have a family.
However, experts have cautioned that there is still a way to go before any such procedures are attempted in humans.
These adult male mice, which each have the genetic material of their two fathers, have gone on to have offspring of their own
'In this study, we report the generation of fertile androgenetic mice,' the Chinese experts say in their paper, published in the journal PNAS.
'Our findings, together with previous achievements of uniparental reproduction in mammals, support previous speculation that genomic imprinting is the fundamental barrier to the full-term development of uniparental mammalian embryos.'
Experts caution that we are not ready to start such experiments in humans, which could be deeply unethical.
Christophe Galichet, research operations manager at the Sainsbury Wellcome Centre in London, points out that the success rate of the experiments was very low.
Of 259 mice embryos that were transferred to female mice, just two survived, grew to adulthood and then fathered their own offspring.
'This research on generating offspring from same-sex parents is promising,' Galichet, who was not involved with the experiments, told New Scientist.
'[But] it is unthinkable to translate it to humans due to the large number of eggs required, the high number of surrogate women needed and the low success rate.'
Today, gay couples who want to have children usually rely on a surrogate mother or father to bring a child into the world.
Today, gay couples who want to have children usually rely on a surrogate mother or father to bring a child into the world (file photo)
How did the scientists do it?Unlike with a pair of heterosexual parents, this means that one of the couple is not actually related to the child. So it's long been a dream for gay couples to raise a child who has genetic material from both fathers (or both mothers).
Back in 2023, researchers revealed they'd been able to create mice from two biological fathers for the first time.
Because mice are actually genetically very similar to us, the promising results hinted the feat could be replicable in humans.
But even if a human child could be birthed from two fathers, it potentially threw a huge ethical quandary into the mix: What if that human child is not able to have children of their own through normal conception when they reach adulthood?
Fortunately, these new experiments suggest this might not be an issue.
The human related to both of his or her fathers would grow up and be able to have a family of their own, the results suggest.
During heterosexual reproduction, genetic material from a male carried by the sperm combines with genetic material from a female contained in the egg, or ovum.
When this happens, a group of genes called 'homologous chromosomes' from the mother come together with those from the father and combine in a process called 'crossing over'.
A gene editing technique was then used to reprogram parts of the sperm DNA to allow an embryo to develop – a process called androgenesis (file photo)
But when both sets of homologous chromosomes come from either two males or two females, the genes don't copy over properly, leading to 'imprinting abnormalities' and developmental defects.
That's why the researchers had to turn to gene editing, which makes tweaks in the DNA, and target genes responsible for imprinting.
Researchers are also considering this approach in larger animals like monkeys – but the technological hurdles will be significantly larger.
Dr Helen O’Neill, molecular geneticist at the University College London, called the new work a 'major step forward'.
'It confirms that genomic imprinting is the main barrier to uniparental reproduction in mammals and shows it can be overcome,' she told New Scientist.
Earlier this year, another Chinese team got mice with two fathers to grow to adulthood by editing 20 different genes in their stem cells, but the rodents weren’t fertile.
What is gene editing?Genome editing enables scientists to make changes to DNA, leading to changes in physical traits.
Scientists use different technologies to do this.
These technologies act like scissors, cutting the DNA at a specific spot.
Then scientists can remove, add, or replace the DNA where it was cut.
The first genome editing technologies were developed in the late 1900s.
More recently, a new genome editing tool called CRISPR, invented in 2009, has made it easier than ever to edit DNA.
The acronym stands for 'Clustered Regularly Inter-Spaced Palindromic Repeats'.
The technique involves a DNA cutting enzyme and a small tag which tells the enzyme where to cut.
By editing this tag, scientists are able to target the enzyme to specific regions of DNA and make precise cuts, wherever they like.
It has been used to 'silence' genes - effectively switching them off.
When cellular machinery repairs the DNA break, it removes a small snip of DNA.
In this way, researchers can precisely turn off specific genes in the genome.
Source: US National Human Genome Research Institute (NHGRI)
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