Horizontal gene transfer in eukaryotes: A biological phenomenon with unknown molecular mechanisms but accumulating DNA evidence

Horizontal gene transfer (HGT) between different organisms is one of the primary forces driving evolution. Recent advances in sequencing and genome analysis technologies have enabled the discovery of evidence for HGT from a wide range of eukaryotic genomes. It is well established that parasitic or symbiotic organisms can transfer genes to their hosts via viruses or transposons. Furthermore, there have been reports of horizontal transfer from one cell to another by apoptotic vesicles or exosomes. This suggests that they may play a role in the onset and recurrence of human diseases, including cancer and metabolic diseases. In this review, we present newly reported cases of HGT in eukaryotic organisms and discuss future research trends.