Diagnostics

​Danish Reference Center for Prion Diseases (DRCPS) is responsible for the diagnostics of Prion diseases in Denmark. At DRCPD we work in a specialized biosafety level 3* and GMO class 1 laboratory to diagnose patients who suffer from various Prion diseases including Creutzfeldt-Jakob disease (CJD), Variably Protease-Sensitive Prionopathy (VPSPr), Fatal Insomnia (FI), and Gerstmann – Sträussler – Scheinker syndrome (GSS). Our diagnostics are based on the advanced molecular biology methods and neuropathological examinations, thus allowing early disease detection as well as post-mortem diagnosis confirmation.  




Overview of diagnostic tests and request forms​

The table indicates what sample is required for a confirmation of suspected diagnosis; which diagnostic method is applied; how detailed is the answer; and what is expected answer waiting time. 

​Diagnosis
​Sample specifics
​Method
​Answer 
​Answer time
Request form
​Sporadic CJD 
Cerebrospinal fluid​
​RT-QuIC
​Positive / negative
​1 week
​RT-QuIC 
​Genetic CJD, GSS, familial FI
​Blood​
​PRNP sequencing
​Pathogenic and non-pathogenic PRNP variants†
​2 weeks
​SangerSeq 
​All CJD types, sporadic FI*, VPSPr and GSS
Brain bio​psy, 



Neuropathology 
Western blot 
PRNP sequencing



​Molecular subtype§ including PrPSc type, distribution pattern, neuropathology and PRNP variants†
​2 weeks,
7 weeks*



​Autopsy request  
+ copy of a death certificate



CJD - Creutzfeldt-Jakob disease; VPSPr - variably protease sensitive prionopathy; FI - fatal insomnia; GSS - Gerstmann–Sträussler–Scheinker syndrome; RT-QuIC – real time quaking induced conversion; PRNP – a gene encoding cellular prion protein (PrPC); PrPSc – misfolded PrPC, which is an infectious, prion disease-causing agent.

* For the diagnosis of sporadic Fatal Insomnia, a whole brain tissue is required due to characteristic neuropathological changes present in specific brain regions. Processing and analyzing the whole brain tissue take up to 7 weeks. 

† PRNP sequencing provides information on single nucleotide variants, octapeptide repeat insertion and deletion mutations. Currently there are ≈60 PRNP mutations linked to prion disease pathogenesis. 

§ Currently, sporadic CJD has 14 distinct molecular subtypes that are determined by polymorphic codon 129 in PRNP, type of present PrPSc, and pattern of PrPSc accumulation and distribution throughout the brain. 

Real-time quaking-induced conversion (RT-QuIC) 

Test of cerebrospinal fluid for the presence of misfolded prion protein.

Indication: investigation of rapidly progressive dementia or other suspected sporadic prion disease.

Sample: Cerebrospinal fluid.

Specifics: 1-2 tubes with 1 ml of blood-free cerebrospinal fluid in a transparent polypropylene tube must be sent on dry ice (at -80oC) together with a completed test request form (see the overview table above).

Answer: Positive / negative. A positive response indicates a sporadic prion disease with a specificity of 100% and a sensitivity of 92%. 
NOTE: RT-QuIC can occasionally detect genetic and iatrogenic prion disease variants too, however the sensitivity for the detection of these variants is significantly lower. 

Time to answer: 1 week.

Sequencing of the prion protein gene (PRNP) 

Screening for ≈60 mutations in the disease associated prion protein gene.

Indication: investigation of suspected genetic prion disease, or family of people with possible genetic prion disease.

Sample: Blood. Sequencing can also be performed on other tissue, e.g., brain tissue.

Specifics: 1 EDTA tube with blood must be sent at 4oC together with a completed test request form (see the overview table above).

Answer: Sequencing of PRNP provides information on single nucleotide variants as well as octapeptide repeat insertion and deletion mutations.
NOTE: Genetic patient/family counseling is not provided at DRCPD, therefor the test must be requested via department/clinic that provides the counseling.

Time to answer: 2 weeks.

Biopsy of brain tissue for examination for prion disease 

Indication: In rare cases, a biopsy is indicated when other non-invasive tests have not led to a diagnosis. Biopsy may be indicated by differential diagnostic consideration versus i.e., vasculitis or other inflammatory conditions.

Sample: Biopsy of brain tissue.

Specifics: Brain biopsy is taken at the neurosurgical department. DRCPD and Department of Pathology must be informed about the delivery of a sample with suspected prion disease beforehand. The sample must be clearly marked “OBS CJD” and shipped in a triple-sealed packaging (see Sample packaging and delivery below for more details). Instruments and equipment used for the biopsy must be handled in accordance with the Danish Health and Medicines Authority's guidelines. 
Answer: Biopsy analyses provide information on misfolded prion protein presence, its distribution pattern and associated neuropathology. If biopsy material is sufficient for additional analyses, PRNP variant and PrPSc type information is also provided.

Time to answer: 2 weeks.​

Brain autopsy on suspicion of prion disease 

Indication: In case of suspicion of prion disease in deceased patient, brain autopsy is needed for definitive prion disease diagnosis establishment.

Sample: Brain.

Specifics: The deceased can be transported to the Department of Pathology, Copenhagen University Hospital, Rigshospitalet, where the brain is removed and properly preserved for diagnostic work-up that includes immunobloting, Sanger sequencing and neuropathological examination. Alternatively, the brain can be removed for examination at a local pathology department and sent to Department of Pathology. A copy of the completed death certificate and autopsy request form (see the overview table above) must be enclosed in both cases. Call neuropathologist Eva Løbner Lund tel. 3545 6333 or the autopsy technician Palle Petersen tel. 3545 9770 to arrange the practical details regarding the transportation and autopsy of deceased, or correct brain preservation and delivery to the Department of Pathology.

Answer: Definitive prion disease diagnosis (including all types and molecular subtypes).

Time to answer: approx. 7 weeks.

Sample packaging and delivery

Potentially infectious biological materials must be packaged in accordance with “UN3373 packaging instruction p650” and must be labeled “UN3373 biological substance category B”. See detailed packaging instructions.​ 

How different sample types must be preserved before and during the transportation is described under specifics of each diagnostic test indicated above.

Our sample reception is open Monday to Friday from 8.00 to 18.00. We recommend that frozen samples are sent at the beginning of the week, to avoid delays in delivery over the weekend. All samples must be sent with relevant completed forms to:

Dr. Ausrine Areskeviciute
Dansk Reference Center for Prionsygdomme 
Prion Laboratoriet, Afdeling for Patologi, 
Opgang 54, Rigshospitalet
Inge Lehmanns vej 14, 4.sal 
2100 København Ø, Danmark




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