Comparison of the pathologic and pathogenic features in six different regions of postmortem brains of three patients with fatal familial insomnia

Fatal familial insomnia (FFI) is an autosomal dominant prion disease clinicallycharacterized by rapidly progressive insomnia, prominent autonomic alterationsand behavioral disturbance. The D178N mutation of the prion protein gene (PRNP)on chromosome 20 in conjunction with methionine at codon 129 is a molecular feature.Although the neuropathological characteristics of FFI are well documented, theneuropathologic and pathogenic features of FFI patients remain poorly understood.Six brain regions of postmortem brains from 3 FFI patients were examined usingimmunohistochemistry, western blot analyses and quantitative real-time PCR. Inall 3 brain specimens, reactive astrogliosis was found to be more severe in thethalamus than in the cortex regions. Western blot analyses showed that all threebrains expressed PrP, but only 2 were associated with significantly weak proteinaseK (PK) resistance. However, the conformational stabilities of PrPSc in the 3 FFIbrains were significantly weaker than those presented in a G114V genetic Creutzfeldt-Jakobdisease (gCJD) case. Immunohistochemistry and western blot analyses showed comparableamounts of neuron-specific enolase (NSE)-positive stained cells and NSE proteinamong the different regions in the three brains. In addition, the transcriptionallevels of glial fibrillary acidic protein (GFAP) and NSE-specific mRNAs were coincidentwith the expression of these proteins. In conclusion, in the present study, wedescribed the detailed regional neuropathology of FFI cases.