Fears of a ‘second wave’ of CJD cases in the UK have been resurrected by a new research paper in the Lancet.

John Collinge, the leading expert on the brain-destroying variant Creutzfeldt-Jakob disease (CJD), and his colleagues report the case of a 30-year old man who died in January this year of the neurological condition. Crucially, this man had a different genetic make up to all the cases seen so far.

Fears over CJD have largely subsided in the UK, following the ‘Mad Cow’ scare in the 1980s over beef contaminated with bovine spongiform encephalopathy (BSE), a CJD-like disease that occurs in cows. At the end of last year these fears were rekindled by the first mentions of the individual whose death is now reported (see: UK braces for more CJD cases).

The reason the case is important is that one version of the human prion protein gene (PRNP) is known to confer a large susceptibility to prion diseases such as CJD. Previous sufferers have all had this highly susceptible profile but in the case reported in the Lancet the individual had a different, supposedly less-susceptible genotype.

Whether this case is the first many of just one of a few is till uncertain.

Millions are thought to have consumed contaminated beef and there is the possibility that those without the susceptibility are not totally protected against CJD but may just have a longer incubation time.

The authors are being cautions and note only that “if individuals with other genotypes are similarly susceptible to developing prion disease after BSE prion exposure, but with longer incubation periods, further cases, which may or may not meet diagnostic criteria for vCJD, would be expected”.

In January of this year a paper in the Lancet Neurology explored some of these issues. It concluded:

To put it prudently, a second wave of CJD with a longer incubation time might hit these shores, but we do not know whether this will be a tidal wave or just an imperceptible ripple.