Pre-mortem diagnosis of Creutzfeldt-Jakob disease by detection of abnormal cerebrospinal fluid proteins.

Creutzfeldt-Jakob disease (CJD) may be difficult to diagnose early or when it has an atypical presentation. We describe two patients with progressive dementia in whom the results of diagnostic brain biopsies were unhelpful. Spinal fluid from these patients, analyzed by two-dimensional electrophoresis, contained two abnormal proteins (Nos. 130 and 131, with relative molecular masses of 26,000 and 29,000 daltons and isoelectric points of 5.2 and 5.1). These findings suggested a provisional diagnosis of Creutzfeldt-Jakob disease, which was confirmed in both patients at autopsy. Detection of these abnormal cerebrospinal fluid proteins appears to be a valuable laboratory adjunct in evaluating patients with an unexplained progressive dementia.