Detection of 14-3-3 brain protein in the cerebrospinal fluid of patients with paraneoplastic neurological disorders

The detection of 14‐3‐3 protein in cerebrospinal fluid by immunoblotting is useful for the diagnosis of Creutzfeldt‐Jakob disease (CJD). We found 14‐3‐3 protein in 10 of 80 (12.5%) patients with paraneoplastic neurological disorders (PNDs), whose presenting symptoms may mimic those of CJD. In 47 of 48 CJD patients, the 14‐3‐3 protein was detected as a single band, and it was detected as a double band in 1 patient. The double‐band pattern was observed in 9 of the 10 14‐3‐3 protein–positive patients with PNDs. The 14‐3‐3 protein assay may be positive in PND patients, but the immunoblotting pattern distinguishes most PND samples from those of CJD.