Stefán Þ. Sigurðsson

Associate Professor at Faculty of Medicine, School of Health Sciences, University of Iceland


E-mail: stefsi (at) 
Phone: +354-525-4839

Department of Biochemistry and Molecular Biology, Læknagarður, Room-574, Vatnsmýrarvegi, 101 Reykjavik

Stefan Sigurdsson received a BS degree in molecular biology from the University of Iceland in 1996 and a master's degree in molecular genetics from the same school in 1998. The focus of his studies was cancer biology, specifically the function of two tumor suppressor genes involved in breast cancer. He obtained his doctorate from the University of Texas 2003 where his research focused to DNA repair and DNA recombination. Stefan worked for five years as a postdoctoral fellow at Cancer Research UK where he studied transcription elongation by RNA polymerase II (RNAPII) and the connection between DNA damage and transcription elongation.

Research focus:

Genomic instability is a characteristic of most cancers, believed to arise because of the inability of cells to deal with damaged DNA. To prevent genomic instability, cells possess a complex network of processes collectively called the DNA damage response (DDR), which detects and repairs damaged DNA. This response is critical to prevent accumulation of mutations and DDR failure can lead to genomic instability and consequently cancer. Individuals with inherited DDR defects, such as mutations in ATM or BRCA2, are strongly associated with high cancer risk.

DNA repair of lesions in transcribed regions of the genome is faster than in the transcriptionally silent regions. The lesions in transcriptionally active genes block the translocation of RNA polymerase II (RNAPII) that serves as a damage recognition signal. Somehow the stalled RNAPII mediates a signal via transcription coupled repair factors such as CSB/Rad26 to recruit the nucleotide excision repair machinery to repair the damage.

The research in the laboratory has two main themes

  1. DNA repair and the cellular response to DNA damage
  2. The connection between RNA polymerase II transcription elongation and DNA damage

The overall aim of our work is to improve our understanding of how cancer develops and identify potential novel therapeutic targets. It is also of crucial importance in the clinic where cancer cells are treated with DNA damaging agents such as ionizing radiation and cytotoxic drugs. Increased knowledge on how the cell responds to such agents is a fundamental task in order to improve current cancer treatments.

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Group members:

Þorkell Guðjónsson, Postdoctoral Research Fellow


1. Characterizing novel regulators of the cellular response to DNA damage.

2. Studying the impact of aberrant splicing on transcription associated DNA repair


Phone: +354-5254238

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Stefán Þór Hermanowicz, PhD student

Project title: Researching the impact of epigenetically modified DNA repair genes on the formation and treatment of various cancers.








Linda Hrönn Sighvatsdóttir, M.Sc. Student

Project title: Researching transcription elongation and the effects microRNAs have on gene expression











Drífa Hrund Guðmundsdóttir, M.Sc. Student.

Project title: Identifying novel regulators of the cellular response to DNA damage


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