Scientists have achieved a groundbreaking milestone by successfully creating mice with two fathers who were able to produce offspring of their own. This advancement brings us closer to the possibility of same-sex couples having children who are genetically related to both parents. However, there are still significant challenges to overcome before this technique can be applied to humans.
Yanchang Wei from Shanghai Jiao Tong University in China utilized a method where two sperm cells were combined in an egg with its nucleus removed. By employing epigenome editing, the team reprogrammed seven specific sites in the sperm DNA to facilitate embryo development.
Out of 259 embryos transferred to female mice, only two male offspring survived to adulthood and successfully produced offspring after mating with females. This low success rate highlights the complexity of creating mammals with two fathers compared to those with two mothers.
The process of creating mice with two fathers involves overcoming a phenomenon known as imprinting, which involves the activation and inactivation of genes on chromosomes inherited from both parents. This epigenetic programming differs between maternal and paternal chromosomes, making it challenging to develop embryos with two sets of paternal chromosomes.
While previous studies have focused on genetic modifications to normalize gene activity, Wei’s team utilized an epigenetic approach using modified CRISPR proteins to add or remove epigenetic labels without altering the DNA sequence. This method proved successful in overcoming genomic imprinting barriers in mammals.
Although the epigenetic approach shows promise for enabling same-sex couples to have genetically related children, the technique’s success rate needs improvement before it can be considered for human use. Challenges such as the need for a large number of eggs, surrogate women, and the low success rate pose significant obstacles.
Despite the low success rate in mice with two fathers, further optimization of the epigenome editing technique could enhance success and animal health. However, translating these findings to humans would require addressing unique challenges specific to human genetics.
If human babies with two fathers were to be created using this method, they would technically be considered three-parent babies due to the mitochondrial DNA inherited from the egg donor. Other techniques, such as turning stem cells into eggs, have also been explored, but their applicability to humans remains uncertain.
