Creutzfeldt -Jakob Disease (CJD) is a rare neurodegenerative disorder of the human central nervous system. It occurs in four main forms, defined essentially according to aetiology: sporadic, variant, iatrogenic and familial. All forms of the disease are characterised by the deposition of an abnormal cellular protein, the prion protein (PrPSO), within the brain. Definitive diagnosis depends on identifying this along with other neuropathological changes such as spongiform degeneration and astrocytic gliosis.
To date variant CJD has followed a relatively stereotyped clinical course with fairly consistent pathological findings. However, various clinico- pathological phenotypes of sporadic CJD have been described. It is believed the disease phenotype is influenced by a number of factors including agent strain (PrP' isotype being used as a surrogate marker), and genotype (particularly a polymorphism at codon 129 of the prion protein gene).
Data on 99 cases of sporadic CJD and 43 cases of variant CJD were analysed. The sporadic CJD cases were divided into 6 sub -groups, according to genotype at codon 129 (either methionine homozygous, valine homozygous or heterozygous) and PrPfes isotype (either type 1 or 2A). Some trends in clinico- pathological phenotype were found. Notably, the methionine homozygous cases with type 1 PrP`eS isotype formed the majority of cases and followed a reasonably uniform disease course. The other groups tended to include atypical cases. These differences did not achieve statistical significance and there was considerable overlap amongst cases.
14 -3 -3 protein and the use of MR imaging were analysed. The results suggest that these investigations may improve the diagnostic classification of sporadic CJD. 2
The variant CJD cases followed a relatively consistent clinico- pathological course, consistent with a distinct aetiology and probably a distinct strain. The data do not support the hypothesis that different strains of the sporadic CJD agent cause distinct clinico- pathological phenotypes.