[Three patients from two families with familial Creutzfeldt-Jakob disease having a point mutation in the prion protein gene at codon 200 (Glu-->Lys)].

We present three patients with Creutzfeldt-Jakob disease (CJD). They lived in Fuji city and its neighboring towns in the eastern part of Shizuoka prefecture. Patient 1 and patient 2 were cousins. Patient 1 developed the illness at the age of 50 in 1987 and died 13 months later. Patient 2 became ill at the age of 73 in 1989 and died seven months later. Patient 3 was related to a familial CJD cases in Yamanashi prefecture, known as Akai's "H" family (Akai et al in 1979, Yamamoto et al in 1986). She became ill at the age of 78 in 1990 and died four months later. Their clinical features were common; rapidly progressive dementia, generalized myoclonus, and periodic synchronous discharges on electroencephalographies. They were autopsied and neuropathologically diagnosed as typical CJD. Molecular genetic analysis of the prion protein (PrP) gene was performed on patient 2 and patient 3 using their frozen brain sections. The results showed a point mutation in the PrP gene at codon 200; GAG to AAG (Glu-->Lys). The eastern part of Shizuoka prefecture is adjacent to Yamanashi prefecture where a large number of patients with CJD including familial cases has been found during the recent 15 years. This study suggests that the patients with CJD in both Yamanashi and Shizuoka prefecture should be re-evaluated by analysis of the PrP gene.