William G. Thilly, ScD



(617) 253-6221
Professor of Genetics, Toxicology, and Biological Engineering




Prof. Thilly holds a Bachelor’s degree in Biology and a Doctor of Science in Nutritional Biochemistry from the Massachusetts Institute of Technology. He became an Assistant Professor of Genetic Toxicology at MIT in 1972. From 1980 to 2001 he was Director of MIT Center for Environmental Health Sciences and joined the Department of Biological Engineering in 2001.


The original aim of Thilly’s research group was to discover the origins of disease-causing mutations in humans. They developed the first quantitative human cell mutation assays (1976), two independent means to measure mutations in human tissues (1983-93), and a protocol to scan mutations in human organs and populations 1996.

Then in 2002 -08 his lab discovered that point mutations in human tissues arise in “metakaryotic” stem cells of the fetal juvenile organs mediated by “unforced errors” of DNA polymerases gamma and beta. Now they have discovered that ds RNA/DNA intermediates are used in genome replication in fetal organogenic and adult cancer stem cells.

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