Gerstmann–Sträussler–Scheinker syndrome (GSS) is an extremely rare, fatal neurodegenerative disorder caused by misfolded prion proteins. It is inherited in an autosomal dominant pattern and arises from pathogenic mutations in the prion protein (PRNP) gene. The abnormal prion protein deposits as amyloid plaques, leading to slowly progressive cerebellar dysfunction and dementia.
Pathogenesis and Clinical Characteristics
Mutations in PRNP, most often P102L and A117V, alter the prion protein and allow it to adopt a β‑sheet–rich conformation that propagates by inducing misfolding of normal PrP. The abnormal protein accumulates mainly in the cerebellum and brainstem, producing amyloid plaques and mild spongiform change. The disease usually begins in mid‑life (30s to 50s) with gait instability, truncal ataxia and dysarthria. As it progresses, patients develop pyramidal signs, extrapyramidal signs, visual disturbances and late-onset dementia. Disease duration ranges from about two to ten years, longer than sporadic Creutzfeldt–Jakob disease. There is no effective therapy; care focuses on symptomatic management.
Clinical Cases and Epidemiology
GSS is extremely rare, with a prevalence estimated between one and ten cases per 100 million individuals. It has been reported in only a few families worldwide, and most affected individuals share one of several PRNP mutations such as P102L, A117V, F198S or H187R. The P102L mutation is the most common and has near‑complete penetrance; affected carriers typically develop a slowly progressive cerebellar syndrome with late dementia. Cases have been identified in Europe, North America and Asia; a 2023 report described a Chinese patient with progressive ataxia and a P102L mutation who was initially misdiagnosed with spinocerebellar ataxia. Diagnosis relies on family history, genetic testing of PRNP, brain MRI and cerebrospinal fluid assays such as RT‑QuIC. Because there is no cure and the disease is universally fatal, genetic counselling and supportive care are essential. GSS illustrates how a single mutation in a normal cellular protein can trigger a self‑propagating misfolded state and cause profound neurodegeneration. Recognising the clinical pattern of cerebellar ataxia followed by dementia and confirming a PRNP mutation allows families to receive counselling and consider surveillance for at‑risk relatives. Research into prion structure and propagation continues to inform our understanding of these rare inherited encephalopathies. Related Terms: Fatal Familial Insomnia, Genetic Creutzfeldt–Jakob Disease, Sporadic Creutzfeldt–Jakob Disease, Variant Creutzfeldt–Jakob Disease, Iatrogenic Creutzfeldt–Jakob Disease.