New variant Creutzfeldt-Jakob disease.

It is now recognised that new variant Creutzfeldt-Jakob disease (CJD) can present during adolescence, so it may be within the experience of any paediatrician. Some observations on prion proteins are made, and some of the features of classical CJD are reviewed. Reports of patients with new variant CJD are given. The possible links between this condition and bovine spongiform encephalopathy (BSE) are considered, especially the finding that certain people who are homozygous for methionine at codon 129 of the prion protein may be particularly susceptible to this infection. The diagnosis of new variant CJD can be difficult. Early sensory and psychiatric symptoms can be suggestive, so can the initial signs of ataxia and involuntary movements. The EEG does not help in this variety. Although not specific some serum and CSF tests may give diagnostic support. It has been claimed that tonsillar biopsy may confirm the diagnosis, but this often necessitates brain biopsy; or the diagnosis may only be made at autopsy. Beliefs about the way infections spread will have to be modified, and more must be learnt about the nature of prions, how they enter the body, and how they spread in the brain.