Tomas Robert Lindahl FRS FMedSci, born 28 January 1938, is a Swedish scientist specialising in DNA damage and repair. He was director of the Clare Hall Laboratories from 1986 to 2005. He was jointly awarded the Nobel Prize for Chemistry in 2015, the Royal Society's Royal Medal in 2007, the Copley Medal in 2010, and the INSERM Prix Etranger in 2009.
Tomas Lindahl's Mutagenesis Laboratory at Clare Hall characterised different DNA repair pathways in a long-term project to provide better understanding of the cellular defence mechanisms against damage to the human genome.
Damaged sites in the chromosomal DNA can result in cell death or cancer, but may be corrected by DNA repair enzymes prior to phenotypic expression. The properties of several nuclear enzymes that remove harmful lesions or local aberrant structures from DNA have been investigated. The absence of such DNA repair factors may result in an increased frequency of malignant transformation, or in some cases may be detected as immunological deficiencies.
Tomas closed his lab at the Clare Hall laboratories in 2009 but remains an Emeritus Group Leader at the Francis Crick Institute.