The Generative Brain

Tear fluid RT-QuIC

RT-QuIC on tear fluid (a Schirmer strip) is a non-invasive prion test from the Goettingen group: 16 of 19 patients positive and 94 of 94 other neurological patients negative in the 2023 NEJM pilot, and with an E200K substrate 84 percent sensitivity in sporadic CJD and 99.5 percent specificity in a grant report. Still a research validation.

Key facts

  • 84 percent sensitivity for sporadic CJD and 70 percent for genetic prion disease (7 of 10) in the first-year grant report; the project aims to look for early signals in healthy PRNP carriers, not yet shown.
  • Limits: Lower sensitivity; prediction of onset in healthy carriers is being studied, not shown.
  • What it asks of the person: Non-invasive.
  • The 2023 pilot found abnormal prion protein in tears of 16 of 19 patients with CJD or genetic prion disease and none of 94 other neurological patients.
  • With a full-length human E200K substrate, tear RT-QuIC had 84 percent sensitivity in sporadic CJD (27 of 32), 70 percent in genetic prion disease (7 of 10) and 99.5 percent specificity (1 of 184 controls positive).
  • Tear seeding activity stayed stable for five days at room temperature.
  • The January 2026 paper from the group reports the E200K substrate raising CSF sensitivity in sporadic CJD from 71 to 92 percent and in fatal familial insomnia from 19 to 75 percent (2025 abstract figures; paper not read in full).
  • A 2026 Lancet Neurology review says tests in blood, tears and urine could become easy platforms for diagnosis and monitoring.

Timeline

  1. 2023NEJM tear fluid pilot published.
  2. 2024First year of the CJD Foundation tear validation grant begins.
  3. 2026E200K substrate paper published.
  4. 2026Lancet Neurology review of prion biomarkers.
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