Prion Diseases

Introduction to Prion Diseases

Prion diseases are characterized by their clinical manifestations, genetic causes, and disease courses, all of which are caused by misfolded prion proteins and ultimately lead to death, according to the American College of Medical Genetics and Genomics 1

The clinical presentation of prion diseases includes early cognitive symptoms such as memory loss and dementia, accompanied by symptoms like ataxia, myoclonus, and pyramidal and extrapyramidal signs, with a median survival time of approximately 5 months, as stated by the American College of Medical Genetics and Genomics 1
Patients may exhibit motor symptoms like progressive cerebellar ataxia and parkinsonism, as well as behavioral changes, such as personality alterations, apathy, or disinhibition, and hallucinations, delusions, depression, and anxiety 1
Sleep dysregulation, sympathetic overactivity, and endocrine abnormalities can also be present, particularly in Fatal Familial Insomnia (FFI) 1

Genetic prion diseases are caused by autosomal dominant mutations in the PRNP gene, with specific mutations like E200K, D178N-129V, and V210I being associated with certain forms of the disease, according to the American College of Medical Genetics and Genomics 1
Other mutations in the PRNP gene, such as P102L, A117V, P105L, and F198S, are also associated with genetic prion diseases, as noted by the American College of Medical Genetics and Genomics 1
Codon 129 in the PRNP gene (methionine or valine) influences disease duration in some genetic prion diseases and the risk of sporadic and iatrogenic forms, as stated by the American College of Medical Genetics and Genomics 1

All prion diseases are caused by the accumulation of misfolded prion proteins (PrPSc) in the brain, leading to progressive dementia, akinetic mutism, and ultimately death, as explained by the American College of Medical Genetics and Genomics 1

The American College of Radiology recommends considering prion disease in patients with rapidly progressive dementia, with key diagnostic findings including rapidly progressive cognitive decline, characteristic MRI findings, presence of 14-3-3 protein in cerebrospinal fluid, and real-time quaking-induced conversion (RT-QuIC) assay positivity 2
PRNP gene sequencing for genetic forms can also aid in diagnosis 2
The traditional genotype-phenotype correlation has weakened over time, with significant phenotypic heterogeneity within and overlap between historical subtypes, making diagnosis and prediction of disease course challenging, as stated by the American College of Medical Genetics and Genomics 1
Symptoms can vary greatly even within the same genetic variant, within families, and between affected identical twins, highlighting the complexity of prion diseases, as noted by the American College of Medical Genetics and Genomics 1
Most prion diseases follow a pattern of initial subtle symptoms, rapid progression to multiple neurological domains, advanced stage with profound dementia and akinetic mutism, and death, with a median survival of approximately 5 months for sporadic CJD 2