Professor Williamson is distinguished internationally for his significant and fundamental contributions to human genetics. His early studies of polysomes helped to establish the existence of mRNA in mammalian cells. He led research into the molecular genetics of the thalassaemias and was the first to clone the human globin genes as cDNAs in 1977. This led to gene mapping for thalassaemias, muscular dystrophies and cystic fibrosis as well as identifying the mutations causing Alzheimer's disease and myotonic dystrophy. He has taken a major interest in gene therapy, using liposomes to introduce genes for CFTR in a clinical trial with cystic fibrosis patients in London and studies of gene therapy for ataxia and thalassaemia in Melbourne. He has a major interest in education and ethics as applied to human genetics.