Final answer:
Creutzfeldt-Jakob disease (CJD) is a rapidly progressive dementia for which the marker is the 14-3-3 protein. This protein can be measured in cerebrospinal fluid (CSF) samples and is associated with elevated levels in CJD patients. Abnormal brain function observed in an electroencephalogram (EEG) also supports the diagnosis of CJD.
Step-by-step explanation:
Creutzfeldt-Jakob disease (CJD) is a rapidly progressive dementia caused by transmissible spongiform encephalopathy (TSE). The marker for CJD is the 14-3-3 protein, which can be measured in cerebrospinal fluid (CSF) samples. Elevated levels of 14-3-3 protein in CSF, along with abnormal brain function observed in an electroencephalogram (EEG), are indicative of CJD.