Mice with 2 fathers obtained by reprogramming DNA

The first mice obtained from two biological fathers thanks to epigenetic reprogramming , which modifies the expression of genes without altering the DNA sequence , are healthy and fertile . The result , still far from being replicated in humans , was published in the journal of the Academy of Sciences of the United States (Pnas) by researchers from the Shanghai Jiao Tong University in China. Mice, like all mammals (including humans), are diploid organisms : this means that each cell of the organism contains two sets of chromosomes , one of maternal origin and one of paternal origin . Embryos obtained with two paternal genomes , despite being diploid, are unable to develop : the main obstacle , explain the Chinese researchers, is genomic imprinting, that is, the presence of chemical modifications on the DNA that modulate the expression of genes depending on whether they are inherited from the mother or the father. To overcome this difficulty , the team led by Yanchang Wei injected two spermatozoa into an egg that had been deprived of the nucleus containing the female DNA. The researchers then went on to act on the DNA deriving from one of the two spermatozoa : thanks to an epigenetic editing technique, they intervened on seven specific sites, changing the chemical modifications that determine imprinting. Thanks to this procedure , 259 embryos were produced , which were then implanted into female mice . In the end , only two males were born and survived , who became adults and in turn reproduced, generating apparently healthy and normal offspring . In principle, therefore, epigenetic editing could represent a new strategy to allow same-sex couples to have their own children . However, the success rate is still too low for the technique to be considered for use on humans.