Born in Scotland, Ashley graduated with 1st class Honors in Physiology and Medicine from the University of Glasgow. He completed medical residency and a PhD at the University of Oxford before moving to Stanford University where he trained in cardiology and advanced heart failure, joining the faculty in 2006. His group is focused on the science of precision medicine. In 2010, he led the team that carried out the first clinical interpretation of a human genome. The article became one of the most cited in clinical medicine that year and was later featured in the Genome Exhibition at the Smithsonian in DC. Over the following 3 years, the team extended the approach to the first whole genome molecular autopsy, to a family of four, and to a case series of patients in primary care.