An inherited prion disease with a PrP P105L mutation: clinicopathologic and PrP heterogeneity.
OBJECTIVE
To clarify a clinical and neuropathologic phenotype of an inherited prion disease associated with a missense mutation at codon 105 in the prion protein (PrP) gene that was originally described as a variant of Gerstmann-Sträussler-Scheinker disease demonstrating spastic paraparesis.


METHODS
Two siblings from a Japanese family are described. PrP gene analyses, neuropathologic studies with immunohistochemistry, and Western blot analysis of the PrP were performed.


RESULTS
Both patients showed a missense (proline-->leucine) mutation at codon 105 and a methionine/valine polymorphism at codon 129 of the PrP gene. Clinically, Patient 1 presented with progressive spastic paraparesis, ataxia, and dementia. Patient 2, the sister of Patient 1, showed prominent action myoclonus and dementia. Neuropathologically, multiple PrP-positive amyloid plaques and diffuse PrP deposition in the deep cortical layers were found in the cerebral cortex with primarily frontal dominant atrophy in both patients. Tau-positive pathologic structures including neurofibrillary tangles, neuropil threads, and dystrophic neurites around the plaques were abundant in the brain of Patient 2. In contrast, the tau pathology was scarce in Patient 1. Western blot analysis of the brain showed different patterns of detergent-insoluble PrP fragments between the patients.


CONCLUSIONS
Despite the identical codon 105 mutation and codon 129 polymorphism of the PrP gene, remarkable clinical and neuropathologic differences, and PrP heterogeneity were present between the affected siblings. The phenotypic variability might be related to PrP heterogeneity.
Department of Neurology, Faculty of Medicine, Medical Research Institute, Tokyo Medical and Dental University, Japan. m-yamada.nuro@med.tmd.ac.jp
M
M
Yamada
Y
Y
Itoh
A
A
Inaba
Y
Y
Wada
M
M
Takashima
S
S
Satoh
T
T
Kamata
R
R
Okeda
T
T
Kayano
N
N
Suematsu
T
T
Kitamoto
E
E
Otomo
M
M
Matsushita
H
H
Mizusawa
D019943:Amino Acid Substitution; D001921:Brain / Q000473:pathology*; D003062:Codon; D005260:Female; D006801:Humans; D007930:Leucine; D008297:Male; D008715:Methionine; D008875:Middle Aged; D020125:Mutation, Missense; D009679:Nuclear Family; D010375:Pedigree; D011110:Polymorphism, Genetic; D017096:Prion Diseases / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D011328:Prions / Q000235:genetics*; D011392:Proline; D014633:Valine
D003062:Codon; D011328:Prions; D011392:Proline; D008715:Methionine; D007930:Leucine; D014633:Valine