[Creutzfeldt-Jakob encephalopathy with mutation E200K. Report of a "sporadic" case].

Introduction: Creutzfeldt Jakob disease (CJD) has the highest incidence of the whole group of transmissible spongiform encephalopathies or prion diseases, which have the unique feature among all pathologies, to be able to appear as infectious/iatrogenic, sporadic or hereditary, being common to all, the deposition of an abnormal prion protein (PrPSc,CJres) in the central nervous system. More than 20 mutations of the gene (PRNP) that encodes the prion protein have been described. We here report a case of CJD(E200K) refered as probable 'sporadic' according to WHO.

Methods: clinical, pathologic, and molecular features of the disease were characterized using EEG, neuropathology, prionprotein (PrP) Western blot and gene (PRNP) analysis.

Results: The patient developed visual hallucinations, myoclonus, memory loss, tremor, disbasia and generalized convulsives seizures dying six months after onset. On neuropathologic examination, spongiform changes were observed and PrP immunopositivity detected. Western blot analysis showed the presence of proteinaseK (PK)-resistant PrP (PrPres) with the nonglycosylatedisoform of approximately 21 kd, and DNA restriction fragment length polymorphism (RFLP) analysis showed the E200K mutation.

Discussion: The PRNP(E200K) mutation is the most frequent cause of the hereditary-familial CJD (fCJD). Clusters of this variety have been described in Chileans, Slovaks from Orava, Jews Israelies of Libyan origin, and Japanese. There was no available data of affected relatives of the patient which have suggested he was fCJD, but due to his Chilean origin PRNP studies were carried out. In fact the clinical and pathology of this familial form, with remarkable exceptions, resembles sporadic cases but has a greater incidence, in these groups than sporadic in the general population.

Conclusion: This patient, although clinically reported as probable 'sporadic', after molecular characterization resulted a CJD(E200K) probably belonging to the Chilean cluster.