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Getting the latest healthcare news for you
Somatic mosaicism — acquired genetic mutations — accounts for more than 20% of systemic autoinflammatory disease (SAID) diagnoses, according to a large UK study. VEXAS syndrome dominated the mosaic cases, while patients with late-onset mosaic CAPS faced a decade-long diagnostic delay and a risk of serious complications. The findings underscore the urgent need to integrate somatic mutation testing into standard diagnostic workflows.
A large retrospective study out of the UK's only nationally accredited reference center for systemic autoinflammatory diseases (SAIDs) has found that somatic mosaicism — where acquired genetic mutations occur in only a subset of cells — is far more common than previously recognized, accounting for over 1 in 5 SAID diagnoses. Researchers analyzed deep next-generation sequencing data from 5,530 patients between 2017 and 2025, identifying 23 distinct mosaic variants across five disease-associated genes.
Among the 403 confirmed SAID patients, VEXAS syndrome was the most prevalent mosaic condition (69%), followed by cryopyrin-associated periodic syndromes (CAPS) at 24%. Patients with adult-onset mosaic CAPS faced a median diagnostic delay of 10 years, with some developing AA amyloidosis — a serious complication of chronic inflammation. VEXAS patients had a median age of onset of 68 years and a 2.5-year diagnostic delay.
Key Takeaways:
Why it matters: These findings reframe how clinicians should approach autoinflammatory disease workups. Somatic mutations aren't rare edge cases — they're a major diagnostic category. Faster, broader genetic testing could prevent years of missed diagnoses and reduce the risk of life-altering complications.
