Genetic prion disease: D178N with 129MV disease modifying polymorphism—a clinical phenotype

• Published in: BMJ neurology open Vol. 2; no. 2; p. e000074
• Main Authors: Tan, Tracie Huey-Lin, Stark, Richard J, Waterston, John A, White, Owen, Thyagarajan, Dominic, Monif, Mastura
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group Ltd 18.09.2020; BMJ Publishing Group LTD; BMJ Publishing Group
• Subjects: Ataxia; clinical neurology; Creutzfeldt-Jakob disease; Electroencephalography; Families & family life; Family medical history; Genotype & phenotype; Hallucinations; Insomnia; Mutation; neurogenetics; Patients; Polymorphism; prion; Prions; Proteins; Short Report; Sleep; clinical neurology; prion; Creutzfeldt-Jakob disease; neurogenetics
• ISSN: 2632-6140; 2632-6140
• DOI: 10.1136/bmjno-2020-000074

BackgroundHuman prion diseases are a group of rare neurological diseases with a minority due to genetic mutations in the prion protein (PRNP) gene. The D178N mutation is associated with both Creutzfeldt-Jakob disease and fatal familial insomnia with the phenotype modified by a polymorphism at codon 129 with the methionine/valine (MV) polymorphism associated with atypical presentations leading to diagnostic difficulty.CaseWe present a case of fatal familial insomnia secondary to a PRNP D178N mutation with 129MV disease modifying polymorphism who had no family history, normal MRI, electroencephalography (EEG), cerebrospinal fluid (CSF) and positron emission tomography findings and a negative real-time quaking-induced conversion result.ConclusionPatients with genetic prion disease may have no known family history and normal EEG, MRI brain and CSF findings. PRNP gene testing should be considered for patients with subacute progressive neurological and autonomic dysfunction.