Gerstmann-Straussler-Scheinker Disease With F198S Mutation Diagnosis on Repeat Genetic Testing: A Case Report.

Gerstmann-Straussler-Scheinker (GSS) disease is a rare hereditary autosomal dominant prion disease characterized by cerebellar ataxia, dysarthria, and progressive dementia. We report a case of GSS disease in a 46-year-old patient who presented with four to six months of ataxia, dysarthria, intermittent tongue biting, and frontal headaches. His DaTscan (dopamine transporter scan) showed absent dopamine uptake in the left putamen and mildly decreased activity in the right putamen, a finding that has only been documented in the literature one other time for this GSS variant. Family history included the death of his father at age 58 from presumed multiple system atrophy (MSA). His symptoms and family history of parkinsonism prompted genetic testing, which revealed a F198S variant in the prion protein gene (PRNP), confirming a diagnosis of GSS disease.