Dr Karen Breen is an experienced and renowned consultant haematologist at Guy’s and St Thomas’s hospital, London. Her specialties include thrombosis, obstetric haematology, and clotting, bleeding, and platelet disorders.

Dr Breen completed her basic medical training whilst in Ireland, achieving her MB BCh in 2000. She later received her membership with the Royal College of Physicians of Ireland before eventually receiving her fellowship with the Royal College of Pathology. Dr Breen received her postgraduate haematology speciality training mostly in Ireland. She later relocated to London to complete research on antiphospholipid syndrome which led to her receiving an MD in 2015.

Dr Breen has maintained a strong interest in her research. She continues to conduct research on antiphospholipid syndrome and thrombosis. Presently, she is involved in several current clinical trials and translational research. Dr Breen has had her work published in various peer-reviewed journals. On a regular basis, Dr Breen lectures both nationally and internationally.