Prion Disease Diagnosis and Management

Definition and Pathophysiology

Abnormal misfolding of the normal prion protein (PrP or PrPc) into pathological conformers called prions (PrPSc) that act as templates for further protein misfolding, leading to neurodegeneration with characteristic spongiform changes in brain tissue, as described by the American College of Medical Genetics and Genomics 1, 3
Accumulation of these misfolded proteins in the brain causing neurodegeneration, according to the American College of Medical Genetics and Genomics 1

Incidence of 1-2 cases per million population per year, accounting for approximately 1 in 6000 deaths, as reported by the American College of Medical Genetics and Genomics 1
Most cases occur in individuals between 55-75 years of age, according to the American College of Radiology 4

Genetic prion diseases are caused by autosomal dominant protein-altering variants in the PRNP gene located on chromosome 20p13, including types such as Gerstmann-Sträussler-Scheinker syndrome (GSS) and fatal familial insomnia (FFI), as described by the American College of Medical Genetics and Genomics 1, 2
Most common pathogenic variants include E200K, P102L, D178N, and various octapeptide repeat insertions, according to the American College of Medical Genetics and Genomics 5

Rapidly progressive dementia is the hallmark presentation, especially in sporadic CJD, with a median survival of approximately 5 months, as reported by the American College of Radiology 4
Early symptoms vary widely but typically progress to profound cognitive impairment, according to the American College of Medical Genetics and Genomics 1
Other common symptoms include akinetic mutism (late stage) and visual disturbances, as described by the American College of Medical Genetics and Genomics and the American College of Radiology 4, 5

Clinical history and neurological examination are essential for diagnosis, according to the American College of Radiology 4
Magnetic resonance imaging (MRI) is preferred over CT for detecting characteristic patterns, as reported by the American College of Radiology 4
Cerebrospinal fluid analysis for real-time quaking-induced conversion assay (RT-QuIC) offers >90% sensitivity and specificity, according to the American College of Medical Genetics and Genomics 1
Genetic testing for PRNP mutations is particularly important even without apparent family history, as described by the American College of Medical Genetics and Genomics 1, 3

Genetic counseling should be offered to all families with a case of prion disease, regardless of apparent family history, due to the possibility of de novo mutations, incomplete penetrance, and misdiagnosis in previous generations, as reported by the American College of Medical Genetics and Genomics 1, 5, 6