Abstract Details

Title RT-QuIC Testing for Prions: Applying a Sensitive but Imperfect Test in Clinical Practice

Topic Aging, Dementia, and Behavioral Neurology

Presentation(s) P5 - Poster Session 5 (11:45 AM-12:45 PM)

Poster/Presentation
Number 2-010

Objective Identify the clinical, laboratory, and pathologic features associated with false negative real-time
quaking-induced conversion (RT-QuIC) testing for prions.

Background Heterogeneity in clinical presentation, abundant mimics, and potential for iatrogenic
transmission emphasize the need for accurate diagnostic tests for Creutzfeldt-Jakob disease
(CJD). While RT-QuIC is an excellent test, false negative results are recognized in clinical
practice.

Design/Methods One-hundred twelve patients with probable or definite prion disease were assessed at two tertiary
care centers from 2013-2021. RT-QuIC testing for prions was performed in cerebrospinal fluid
(CSF) in all patients via the National Prion Disease Pathology Surveillance Center (Cleveland,
OH). Demographic data, clinical features, and results of common tests and laboratory studies
were abstracted from electronic medical records, and differences between RT-QuIC positive and
negative patients considered using univariate statistics.

Results Initial RT-QuIC testing was negative in 12/112 patients (sensitivity 89%). Median age at
presentation was younger in RT-QuIC negative patients (56.9 vs 66 years, p<0.01), who were
also less likely to present with ataxia (3/12 vs 61/100, p=0.03). CSF cell count, protein, and
glucose levels were similar between cohorts, while rates of 14-3-3 positivity (2/12 vs 77/100,
p<0.01) and median CSF total tau levels were lower in RT-QuIC negative patients (2318 vs 4001
pg/mL, p<0.01). RT-QuIC negative patients also had a longer median days from symptom onset
to first presentation (125 vs 47, p=0.04), and longer symptomatic disease duration (530 vs 148,
p<0.01). Two RT-QuIC-negative patients underwent repeat testing, of which both were positive.

Conclusions RT-QuIC is a sensitive yet imperfect measure necessitating incorporation of other test results
when prion disease is suspected. Patients with negative RT-QuIC had lower CSF biomarkers of
neuronal damage (total-tau and 14-3-3) and longer symptomatic duration of prion disease raising
the possibility that false negative RT-QuIC testing may associate with a more indolent disease
course.

Authors/Disclosures
Gregory S. Day, MD, MSc, FAAN (Mayo Clinic) PRESENTER	Dr. Day has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Arialys Therapeutics. Dr. Day has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for DynaMed (EBSCO Health). Dr. Day has or had stock in ANI Pharmaceuticals. The institution of Dr. Day has received research support from National Institutes of Health / NIA. The institution of Dr. Day has received research support from National Institutes of Health / NINDS. The institution of Dr. Day has received research support from Amgen Pharmaceuticals. The institution of Dr. Day has received research support from AVID Radiopharmaceuticals. Dr. Day has received personal compensation in the range of $500-$4,999 for serving as a Presenter at Annual Meeting (CME) with ��ɫ��. Dr. Day has received personal compensation in the range of $500-$4,999 for serving as a Content Development (CME) with PeerView, Inc. Dr. Day has received personal compensation in the range of $5,000-$9,999 for serving as a Content Development (CME) with Continuing ��ɫ��, Inc. Dr. Day has received personal compensation in the range of $5,000-$9,999 for serving as a Content Development (CME) with Ionis Pharmaceuticals. Dr. Day has received personal compensation in the range of $500-$4,999 for serving as a ��ɫ��al Case Development + Presentation (video) with PeerDirect (P\S\L Group). Dr. Day has received personal compensation in the range of $500-$4,999 for serving as a Content Development / Presentation (non-CME) with MJH Life Sciences (NeurologyLive). Dr. Day has a non-compensated relationship as a Clinical Director with Anti-NMDA Receptor Encephalitis Foundation that is relevant to AAN interests or activities.
Samuel M. Jones, MD (Mayo Clinic)	Dr. Jones has nothing to disclose.
Evelyn Lazar, MD (JFK Medical Center)	Dr. Lazar has nothing to disclose.
Amanda L. Porter, MD (Mayo Clinic)	Dr. Porter has nothing to disclose.
Christian C. Prusinski, DO (Christopher J. Prusinski, DO, PA)	Dr. Prusinski has nothing to disclose.
Matthew Brier, MD, PhD (Washington University)	Dr. Brier has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Genentech. The institution of Dr. Brier has received research support from NIH.
Bob Bucelli, MD, PhD (Washington University)	Dr. Bucelli has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Biogen . Dr. Bucelli has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Biogen. Dr. Bucelli has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Regeneron. Dr. Bucelli has received personal compensation in the range of $10,000-$49,999 for serving as an Expert Witness for Hamilton Weber. Dr. Bucelli has received personal compensation in the range of $5,000-$9,999 for serving as an Expert Witness for O'Bryan Brown and Toner. Dr. Bucelli has stock in Neuroquestions.com. An immediate family member of Dr. Bucelli has stock in Neuroquestions.com. The institution of Dr. Bucelli has received research support from Biogen. The institution of Dr. Bucelli has received research support from Ionis.

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