Familial Creutzfeldt–Jakob disease homozygous to the E200K mutation: clinical characteristics and disease course

Objective: To characterize the demographic, clinical features and disease course of familial Creutzfeldt–Jakob disease (fCJD) patients homozygous to the E200K mutation. Methods: The Israeli National CJD Database was screened for patients homozygous to the E200K mutation. Patients' demographic data, clinical presentation and neurological findings, tau protein levels in the cerebrospinal fluid (CSF) and EEG, were assessed. Results: Ten homozygous E200K patients were identified (80% males). Average age of onset was 47.5 ± 6.1 years (range 40–56) and the average age of death was 49.3 ± 7. 7 years (range 42–63) with average disease duration of 27.7 ± 9.7 months (range 2–97). Initial clinical presentation included behavioral change in 4/10 patients, cognitive decline in 3/10 patients and focal neurological deficits in 2/10 patients. Throughout the disease course, the clinical signs in descending order of prevalence included cerebellar (70%), brainstem (60%), extrapyramidal (50%), pyramidal (50%), frontal lobe signs (30%), and disturbances of ocular motility (30%) Compared to the 228 heterozygous E200K fCJD patients, the 10 homozygous patients were significantly younger at disease onset (47.5 vs 59.7 years, p < 0.001), had a longer disease duration (27.7 vs 8.5 months, p < 0.001) and presented more frequently with behavioral changes as initial manifestation (4/10 vs. 34/228, p = 0.05). Conclusions: Homozygous E200K fCJD patients are characterized by a relatively younger age of onset and longer disease duration. Behavioral changes as a presenting symptom were more common in homozygous patients and cerebellar dysfunction was the most common neurological manifestation throughout the disease course.