[Prion disease surveillance in Japan: analysis of 1,241 patients].

The Creutzfeldt-Jakob Disease (CJD) Surveillance Committee has identified 1,241 patients with prion diseases during 1999-2009, including 953 with sporadic CJD (sCJD)(76.8%), 207 with genetic prion diseases (16.7%), 78 with environmentally acquired prion diseases (6.3%), and 3 with unclassified CJD. Among atypical cases of sCJD, most common was MM2 type including the cortical and thalamic forms. The genetic cases included 84 with a PrP V180I mutation (40.6%), 37 with a P102L mutation (17.9%), 34 with a E200K mutation (16.4%), 32 with a M232R mutation (15.5%), 4 with a P105L mutation (1.9%), and so on. The environmentally acquired cases included 77 with dura mater graft-associated CJD (dCJD) and one with variant CJD (vCJD). Combined with the results by the previous surveillance systems, a total number of dCJD in Japan was 135. The vCJD patient had a history of short stay in the UK and presented with periodic electroencephalogram in the late stage. Although there was no evidence of association of surgical procedures or blood transfusion with sCJD, 4.5% of the sCJD patients underwent operations after the onset of sCJD, including neurosurgical for 0.8% and ophthalmic for 1.9%, requiring more attention on prion diseases to reduce the iatrogenic risk.