Genetic Creutzfeldt-Jakob disease-M232R with the cooccurrence of multiple prion strains, M1 + M2C + M2T: Report of an autopsy case

V180I genetic Creutzfeldt-Jakob disease: Severe degeneration of the inferior olivary nucleus in an autopsied patient with identification of the M2T prion strain

Genetic Creutzfeldt-Jakob disease (gCJD) with a V180I mutation (V180I gCJD) is the most common type of gCJD in Japan, characterized by an older age at onset, slower progression, and moderate to severe cortical degeneration with spongiform changes and sparing of the brainstem and cerebellum. Degeneration of the inferior olivary nucleus (IO) is rarely observed in patients with CJD but is known to occur in fatal familial insomnia (FFI) and MM2-thalamic-type sporadic CJD (sCJD-MM2T) involving type 2 prion protein (M2T prion). Here we report on an 81-year-old Japanese woman who initially developed depressive symptoms followed by progressive cognitive impairment, myoclonus, and hallucinations and died after a clinical course of 23 months. Insomnia was not evident. Genetic analysis of the prion protein (PrP) identified a V180I mutation with methionine/valine heterozygosity at codon 129. Pathologic analysis demonstrated extensive spongiform degeneration, neuronal loss in the cortices, and weak synaptic-type PrP deposition. Except for IO degeneration, the clinicopathologic features and Western blotting PrP band pattern were compatible with those of previously reported V180I gCJD cases. Quantitative analysis revealed that the neuronal density of the IO, especially in the dorsal area, was considerably reduced to the same extent as that of a patient with sCJD-MM2T but preserved in other patients with V180I gCJD and sCJD-MM1 (this patient, 2.3 ± 0.53/mm2 ; a patient with sCJD-MM2T, 4.2 ± 2; a patient with V180I gCJD, 60.5 ± 9.3; and a patient with sCJD-MM1, 84.5 ± 17.9). Use of the protein misfolding cyclic amplification (PMCA) method confirmed the presence of the M2T prion strain, suggesting that the latter might be associated with IO degeneration in V180I gCJD. Autopsy studies are necessary to better understand the nature of CJD, since even if patients present with the common clinical picture, pathologic analysis might provide new insights, as was the case here.

Human prion diseases and the prion protein - what is the current state of knowledge?

Prion diseases and the prion protein are only partially understood so far in many aspects. This explains the continued research on this topic, calling for an overview on the current state of knowledge. The main objective of the present review article is to provide a comprehensive up-to-date presentation of all major features of human prion diseases bridging the gap between basic research and clinical aspects. Starting with the prion protein, current insights concerning its physiological functions and the process of pathological conversion will be highlighted. Diagnostic, molecular, and clinical aspects of all human prion diseases will be discussed, including information concerning rare diseases like prion-associated amyloidoses and Huntington disease-like 1, as well as the question about a potential human threat due to the transmission of prions from prion diseases of other species such as chronic wasting disease. Finally, recent attempts to develop future therapeutic strategies will be addressed.

Prion Mutations in Republic of Republic of Korea, China, and Japan

Prion gene (PRNP) mutations are associated with diverse disease phenotypes, including familiar Creutzfeldt-Jakob Disease (CJD), Gerstmann-Sträussler-Scheinker disease (GSS), and fatal familial insomnia (FFI). Interestingly, PRNP mutations have been reported in patients diagnosed with Alzheimer's disease, dementia with Lewy bodies, Parkinson's disease, and frontotemporal dementia. In this review, we describe prion mutations in Asian countries, including Republic of Republic of Korea, China, and Japan. Clinical phenotypes and imaging data related to these mutations have also been introduced in detail. Several prion mutations are specific to Asians and have rarely been reported in countries outside Asia. For example, PRNP V180I and M232R, which are rare in other countries, are frequently detected in Republic of Korea and Japan. PRNP T188K is common in China, and E200K is significantly more common among Libyan Jews in Israel. The A117V mutation has not been detected in any Asian population, although it is commonly reported among European GSS patients. In addition, V210I or octapeptide insertion is common among European CJD patients, but relatively rare among Asian patients. The reason for these differences may be geographical or ethical isolation. In terms of clinical phenotypes, V180I, P102L, and E200K present diverse clinical symptoms with disease duration, which could be due to other genetic and environmental influences. For example, rs189305274 in the ACO1 gene may be associated with neuroprotective effects in cases of V180I mutation, leading to longer disease survival. Additional neuroprotective variants may be possible in cases featuring the E200K mutation, such as KLKB1, KARS, NRXN2, LAMA3, or CYP4X1. E219K has been suggested to modify the disease course in cases featuring the P102L mutation, as it may result in the absence of prion protein-positive plaques in tissue stained with Congo red. However, these studies analyzed only a few patients and may be too preliminary. The findings need to be verified in studies with larger sample sizes or in other populations. It would be interesting to probe additional genetic factors that cause disease progression or act as neuroprotective factors. Further studies are needed on genetic modifiers working with prions and alterations from mutations.