The Atlantis Plague - A.G. Riddle (2013) Legion Books 

The Atlantis Gene has become a pandemic.  It either causes a person to evolve or devolve.  A drug is developed for those who devolved, only it treats just the symptoms, not the disease.  Another group wants to simply wait for the complete results of the pandemic so the new race can rule the planet.  This becomes open warfare.  One researcher finds that looking into the past, at the events occurring at the same time as sudden changes in human DNA might be the only answer.