Summary: A landmark study provides the strongest evidence yet for a theory proposed seven decades ago: somatic mutations—DNA changes that arise during a person’s life—can drive common autoimmune diseases. The research team found that immune cells, especially B cells, accumulate mutations that effectively “release the brakes” on immune control, enabling these cells to attack healthy tissues. The findings reveal a previously hidden layer of evolution inside the immune system that resembles the early stages of cancer development.
Using ultra-accurate sequencing methods, the investigators detected rare, disease-associated mutations in immune cells from patients with thyroid autoimmunity. These results point toward a new model for autoimmune disease and suggest a route to precision treatments that target mutant immune cell clones rather than suppressing the entire immune system.
Key Facts
- New paradigm: This study gives compelling evidence that somatic mutations—long associated with cancer—also play a central role in common autoimmune diseases.
- Thyroid disease focus: The research examined Hashimoto’s disease and Graves’ disease, two leading causes of thyroid dysfunction, and found consistent mutation patterns in both.
- Precision medicine potential: Current treatments broadly suppress immunity. Identifying mutated clones opens the possibility of targeted therapies that spare the healthy immune system.
- Historical context: The idea that “forbidden” or self-reactive lymphocyte clones emerge through mutation dates back to the 1950s; only now has technology enabled direct testing.
- Population impact: Autoimmune diseases affect an estimated 5–10% of people worldwide, making improved diagnostics and treatments a high priority.
Source: Wellcome Sanger Institute
Overview: Researchers from the Wellcome Sanger Institute, Cambridge University Hospitals NHS Foundation Trust, the University of Cambridge and collaborators applied state-of-the-art genomics techniques to search for driver mutations in thyroid autoimmunity. Their results, reported in Nature (14 April), change how we understand molecular drivers of autoimmune disease and point to new diagnostic and therapeutic directions.
Autoimmune disease covers many conditions in which the immune system mistakenly attacks the body’s own tissues. Examples include rheumatoid arthritis, multiple sclerosis, systemic lupus erythematosus and type 1 diabetes. Although these conditions affect a substantial fraction of the global population, their precise molecular causes remain unclear.
Somatic mutations are DNA changes that occur after conception and are not inherited. They are well known to cause cancer, but until recently it was difficult to detect low-frequency somatic mutations in non-cancer tissues. Advances in sequencing—particularly methods developed at the Sanger Institute—now permit ultra-sensitive detection of rare mutations, enabling researchers to study their role in autoimmune disease.
Since the 1950s, scientists have hypothesized that somatic mutations in lymphocytes (white blood cells such as B cells) could disable immune checkpoints and allow self-reactive cells to persist. Testing this hypothesis has been hard because autoimmunity typically involves many separate immune cell clones rather than a single expanding tumour, so each mutant clone often makes up a tiny fraction of affected tissue. The new study overcame this challenge using targeted, high-accuracy approaches.
The team focused on thyroid autoimmune disease, analyzing tissue and blood samples from patients with Hashimoto’s and Graves’ disease. They applied NanoSeq, an ultra-accurate single-molecule sequencing method developed recently at the Sanger Institute, to detect rare mutations that standard sequencing would miss. Many B cells carried loss-of-function mutations in genes that normally restrain immune responses.
Further single-cell and spatial analyses showed that multiple independent B cell clones in each patient harbored mutations in the same immune-checkpoint genes. Two genes stood out: TNFRSF14 (also called HVEM) and CD274 (PD-L1). In many patients, distinct B cell clones had independently lost function in these genes. Some clones accumulated multiple driver mutations—up to four to six—over years, quietly building genetic changes before clinical symptoms emerged. This pattern of polyclonal somatic evolution—many independent clones acquiring mutations—had previously been unexpected outside cancer.
Experimental evidence and clinical observations indicate that loss or inhibition of these immune-checkpoint genes can provoke thyroid autoimmunity. The new results show that such mutations commonly arise in autoimmune patients, supporting the idea that mutated lymphocyte clones contribute to disease.
The study provides the clearest evidence so far that somatic mutations create a hidden landscape of selection in immune cells during autoimmunity. While these findings are compelling, the authors note that more work is needed to determine whether these mutations initiate disease or worsen it over time. Early investigations in other autoimmune conditions suggest similar mutation patterns, but those results are preliminary.
Dr Andrew Lawson, co-first author at the Wellcome Sanger Institute, emphasized that the combination of NanoSeq and other high-resolution methods now permits rigorous study of somatic mutations across diseases beyond cancer. Co-first author Dr Pantelis Nicola highlighted the clinical implications: current broad immunosuppression leaves patients exposed to infection and side effects; targeted therapies against mutant clones could improve outcomes while preserving normal immunity.
Independent experts praised the work as a major advance in understanding autoimmune pathogenesis. Senior author Dr Iñigo Martincorena noted that while further studies are required, these findings could usher in a new era of research and treatment for autoimmune disease.
Funding: This research was supported in part by Wellcome. Full acknowledgements are listed in the published paper.
Key Questions Answered
A: In some respects, yes: both processes involve cells that acquire DNA mutations and evade normal biological controls. Unlike cancer, however, these mutated immune cells do not typically expand into a single, rapidly growing tumour. Instead, multiple small clones persist in blood and tissues and drive an immune attack against the body.
A: No. These are somatic mutations that occur during life and are not passed from parents to children. This explains why autoimmune disease can arise without a family history.
A: Current therapies broadly suppress the immune system. If validated in further studies, these findings could enable targeted treatments that specifically eliminate or neutralize the mutant immune cell clones, reducing side effects and infection risk.
Editorial Notes
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full by editorial staff.
- Additional explanatory context was added by staff to aid understanding.
About this genetics research news
Author: Susannah Young
Source: Wellcome Sanger Institute
Contact: Susannah Young, Wellcome Sanger Institute
Image credit: Neuroscience News
Original research: Closed access. Title: Polyclonal selection of immune checkpoint mutations in thyroid autoimmunity. Authors include Pantelis A. Nicola, Andrew R. J. Lawson, Iñigo Martincorena and colleagues. Journal: Nature. DOI: 10.1038/s41586-026-10493-9.
Abstract (summary): The immune system relies on multiple checkpoints to prevent activation of self-reactive lymphocytes. A long-standing hypothesis proposes that somatic mutations in immune-regulatory genes allow some lymphocytes to bypass tolerance. Using whole-exome sequencing and the highly accurate NanoSeq protocol, researchers searched comprehensively for driver mutations in autoimmune thyroid disease. They found multiple independent B cell clones with loss-of-function mutations in immune-checkpoint genes TNFRSF14 (HVEM) and CD274 (PD-L1), plus less frequent mutations in other immune genes. In highly inflamed biopsies, tens to hundreds of independent checkpoint-mutant clones were detected. Laser microdissection, methylation sequencing, spatial transcriptomics, immunostaining, single-nucleus DNA sequencing and antibody synthesis localized these mutations to B cells, confirmed self-reactivity for some clones, and revealed clones carrying multiple driver mutations. Although each clone typically represented less than 1% of cells, the cumulative burden of mutant clones comprised a substantial fraction of B cells in donors. These results support a model in which polyclonal somatic evolution of lymphocytes can enable escape from tolerance and contribute to autoimmune disease.