Search

Decreased levels of β-amyloid (Aβ) 1-42 in cerebrospinal fluid (CSF) are characteristic for Alzheimer's disease (AD) and are also evident in Creutzfeldt-Jakob disease (CJD). Aβ plaques are thought to be responsible for this decrease in AD patients, whereas such Aβ plaques are rarely seen in CJD. To investigate the Aβ pattern in brain and CSF of neuropathologically confirmed CJD and AD patients we used an electrophoretic method to investigate Aβ peptide fractions which are not accessible to ELISA and immunohistochemistry. We analyzed Aβ peptides in the CSF of autopsy-confirmed CJD and AD patients and the corresponding brain homogenates using a quantitative urea-based Aβ electrophoresis immunoblot (Aβ-SDS-PAGE/immunoblot).The CSF Aβ1-42 decrease correlated with the brain Aβ load in AD, but not in CJD. There was no difference in the soluble fractions of brain homogenate in AD and CJD. We therefore conclude that different mechanisms in AD and CJD are responsible for the Aβ1-42 decrease in the CSF.

Clinical and pathological changes in familial Creutzfeldt-Jakob disease (CJD) cases may be similar or indistinguishable from sporadic CJD. Therefore determination of novel mutations in PRNP remains of major importance. We identified two different rare mutations in codon 188 of the prion protein gene (PRNP) in four patients suffering from a disease clinically very similar to the major subtype of sporadic CJD. Both mutations result in an exchange of the amino acid residue threonine for a highly basic residue, either arginine (T188R) or lysine (T188K). The T188R mutation was found in one patient and the T188K mutation in three patients. The prevalence of mutations at codon 188 of PRNP was tested in 593 sporadic CJD cases and 735 healthy individuals. Neither mutation was found. The data presented here argue in favor of T188K being a pathogenic mutation causing genetic CJD. Since one individual with this mutation, who is the father of a clinically affected patient with T188K mutation, is now 79 years old and shows no signs of disease, this mutation is likely associated with a penetrance under 100%. Further observations will have to show whether T188R is a pathogenic mutation.

Atypical clinical course and low sensitivity of established diagnostic tests are the main diagnostic problems in the MV2 subtype of sporadic Creutzfeldt-Jakob disease (sCJD). Clinical symptoms and signs, MRI, EEG and biochemical CSF markers were studied in 26 patients. Histological findings were semiquantitatively evaluated. Compared with typical sCJD, the disease duration was prolonged (median 12 months). Dementia, ataxia and psychiatric symptoms were present in all patients. Extrapyramidal signs were observed in 88%. T2-weighted MRI showed basal ganglia hyperintensities in 90%. Increased thalamic signal intensity was detected in 88% on diffusion-weighted MRI. Increased CSF tau-protein was found in 83%, and the 14-3-3 test was positive in 76%. The EEG revealed periodic sharp wave complexes in only two patients. Kuru plaques, severe thalamic and basal ganglia gliosis and spongiform changes, and neuronal loss in the pulvinar were the prominent histological features. At least one of the three diagnostic tests (MRI, tau- and 14-3-3 protein) supported the clinical diagnosis in all patients. MRI was the most sensitive of the diagnostic tests applied. Thalamic hyperintensities were observed unusually frequently. Prolonged disease duration, early and prominent psychiatric symptoms, absence of typical EEG, thalamic hyperintensities on MRI and relatively low 14-3-3 protein sensitivity may be suspicious for variant CJD. However, distinct sensory symptoms and young age at onset, which are often found in the latter, are not common in the MV2 subtype, and the pulvinar sign was observed in only one case.

A case of Creutzfeldt-Jakob disease (CJD) with a rare mutation of the prion protein (PrP) gene (PRNP) at codon 208 (R208H) is described. By comparison with two preceding reports, the case described here displayed two distinct biochemical and neuropathological features. Western blot analysis of brain homogenates showed, in addition to the commonly observed three bands of abnormal protease-resistant PrP isoform (PrP(Sc)), an additional band of about 17 kDa. Neuropathological examination of the post mortem brain revealed tau pathology in the hippocampus and entorhinal cortex, as well as ballooned neurons in the cortex, hippocampus and subcortical gray matter.