John has trained in paediatrics, medical genetics and genetic pathology. In January 2016 he relocated from Sydney, and took up the inaugural Chair of Genomic Medicine at the Murdoch Childrens Research Institute and the University of Melbourne. He has active laboratory-based research programs in Rett syndrome, phenylketonuria (PKU) and the mitochondrial respiratory chain disorders. A major research focus is the application of next generation sequencing technologies for disease gene discovery in rare Mendelian disorders. He has co-authored over 240 research papers (74 relating to Rett syndrome and related disorders), 11 major reviews and contributed to 14 book chapters (two relating to Rett syndrome – published in 2018).
John is a former President of the Human Genetics Society of Australasia (2005-2007), and member of the Human Genetics Advisory Committee (2009-2015). In 2010 he became a Member of the General Division of the Order of Australia (AM) for service to human genetics, particularly the metabolic disorders of children, as a researcher and clinician.