Mary E. Brunkow Biography: Nobel Prize Laureate in Physiology or Medicine 2025

In 2025, Mary Elizabeth Brunkow, an American molecular biologist and immunologist, received global recognition for her role in one of the most significant breakthroughs in immunology. Along with Fred Ramsdell and Shimon Sakaguchi, she was jointly awarded the Nobel Prize in Physiology or Medicine for their pioneering discoveries about peripheral immune tolerance — the process that prevents the immune system from attacking the body’s own cells.

Their work centered on identifying and understanding the FOXP3 gene, a crucial regulator of the immune system, and marked a turning point in modern immunology.

Early Life and Education of Mary Elizabeth Brunkow

Mary Elizabeth Brunkow was born in 1961 in Portland, Oregon. She completed her schooling at St. Mary’s Academy in 1979. Her early interest in biology led her to pursue a Bachelor of Science in Molecular and Cellular Biology from the University of Washington, which she completed in 1983.

Brunkow continued her academic journey at Princeton University, where she earned her Ph.D. in Molecular Biology in 1991. Her doctoral advisor was Dr. Shirley M. Tilghman, a prominent molecular biologist who later became President of Princeton University. Brunkow’s dissertation focused on the expression and function of the H19 gene in transgenic mice, laying the foundation for her future work in genetics and immunology.

Career and Research Journey

After completing her doctorate, Brunkow entered industry research in the Seattle area, working at Celltech R&D in Bothell, Washington. It was here that she collaborated with Fred Ramsdell on research that would eventually change the understanding of immune regulation.

Together, they investigated a mysterious genetic condition found in a type of laboratory mouse known as the scurfy mouse, which suffered from uncontrolled immune responses and fatal inflammation. Their study led to the discovery of the FOXP3 gene, which was responsible for regulating immune cell activity.

Later, Brunkow joined the Institute for Systems Biology in Seattle, where she served as Senior Program Manager, continuing her work in systems-level biological research.

Discovery of the FOXP3 Gene

In 2001, Brunkow co-authored a landmark paper published in Nature Genetics, which identified the gene behind the scurfy mouse’s immune disorder. Initially called “scurfin,” this gene was later renamed FOXP3.

The discovery showed that mutations in FOXP3 disrupt the function of a special group of immune cells known as regulatory T cells (Tregs). These cells play a vital role in maintaining immune tolerance — the body’s ability to distinguish between its own cells and foreign invaders.

When FOXP3 is defective, Tregs cannot control other immune cells properly, leading to autoimmune diseases and severe inflammation. This finding provided the molecular basis for understanding how the immune system maintains balance and prevents self-destruction.

Impact on Immunology and Medicine

Brunkow’s work was a cornerstone for modern immunological research. The identification of FOXP3 not only clarified the genetic cause of certain immune disorders but also paved the way for new therapeutic strategies.

Subsequent studies inspired by her research have contributed to treatments for autoimmune diseases and even anti-sclerostin therapy, including the development of romosozumab, a drug used to treat osteoporosis. Her discovery continues to influence medical research, from autoimmune disease management to cancer immunotherapy.

Nobel Prize in Physiology or Medicine 2025

On October 6, 2025, the Nobel Assembly at the Karolinska Institute in Stockholm, Sweden, awarded the Nobel Prize in Physiology or Medicine jointly to Mary Elizabeth Brunkow, Fred Ramsdell, and Shimon Sakaguchi.

They were honored for their discoveries concerning peripheral immune tolerance — a recognition of decades of groundbreaking research that transformed our understanding of how the immune system maintains self-control.