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From: TSS ()
Subject: Mad cow disease 'a ticking timebomb'
Date: January 2, 2008 at 7:11 pm PST

Mad cow disease 'a ticking timebomb'

By RHIANNON EDWARD

FEARS of a new wave of deaths caused by the human form of mad cow disease have been triggered by a type of variant CJD never seen before.

Scientists who examined the brain of a 39-year-old woman killed by the disease found unusual patterns of damage.

The woman also had a distinct genetic make-up associated with her illness that was not shared by other victims.

Investigations are still at an early stage, but the findings point to the possibility of a further group of people succumbing to vCJD as a result of having

eaten infected beef in the 1980s.

The disease, linked to misshapen prion proteins in the brain, has varying incubation periods according to genetic make-up.

Experts believe that for many of those infected the timer could still be ticking, and in some cases the incubation period might exceed 50 years.

VCJD originally arose in cattle as bovine spongiform encephalopathy (BSE), or "mad cow disease", before appearing in a new form in humans.

The incurable disease leaves the brain riddled with holes, like a sponge, causing a loss of mental faculties and eventually death.

Since the disease was first recognised in 1995 there have been 162 confirmed or suspected vCJD deaths in the UK.

Fears of an epidemic involving hundreds of thousands of deaths abated after the number of annual deaths peaked at 28 in 2000 and then quickly fell.

In the year up to 30 November, 2007 there were just four definite or probable cases.

All these people had the MM version of the gene that makes prions, carried by 40 per cent of the population. The woman had a different gene variant.

The case was described in the journal Archives of Neurology and reported yesterday in New Scientist magazine.

http://news.scotsman.com/scitech/Mad-cow-disease-39a-ticking.3635958.jp

January 3, 2008

Doctors on alert for new group of ‘mad cow’ victimsMark Henderson, Science Editor

Fears that the human version of “mad cow” disease could cause further waves of infection have been heightened by the first case yet identified in a person who is genetically distinct from previous patients.

All the deaths in Britain from the-brain condition have so far occurred among people with a particular genetic profile carried by about 40 per cent of the population. However, a 39-year-old woman who died recently of Creutzfeldt-Jakob disease (CJD) has now been found to have had a different genetic type to other cases caused by eating beef infected with rogue prion proteins.

If she is found to have had the new variant of CJD linked to bovine spongiform encephalopathy (BSE), her case could signal that the disease is starting to affect a second genetic group in whom it has a longer incubation period. Most scientists think it more likely that she developed the sporadic version of CJD that is not caused by eating infected beef.

Simon Mead, from University College London, who examined the woman’s brain after her death, said that although there was not yet any cause for alarm the case showed the importance of continued surveillance.

“The final conclusion remains open,” he told New Scientist magazine. “It is waving the flag for neurologists to watch for other cases.”

The results of genetic tests on the woman have been published in the journal Archives of Neurology.

Confirmation of which form of CJD the patient had will be important because predictions for the number of cases that will be caused by exposure to infected beef in the 1980s and early 1990s depend on how the disease affects people with three particular genetic profiles.

Initial forecasts of up to 500,000 infections have been cut radically, and more recent estimates for future deaths range from only 70 to about 4,000. The likely scale depends on the susceptibility of two genetic groups in whom the disease has yet to be found, and whose susceptibility is not known.

The prion protein that malfunctions in CJD has three versions. About 40 per cent of the population have two copies of the amino acid methionine at a key point in the protein. All cases of new variant CJD reported so far have occurred among people with this genotype, known as MM.

Another 50 per cent of the population have one copy of methionine and one copy of a different amino acid, valine, giving them the genotype MV. Another 10 per cent have two copies of valine, and are described as VV.

The new case is the first with similarities to new variant CJD to be identified in a VV patient, which could suggest that it is starting to affect a second genetic group in whom there is a longer incubation period.

If people with the VV and MV variants are also susceptible, which is un known, they may have longer incubation periods than those with MM, and there may be further peaks of infection in the future. Mouse research suggests that both groups are susceptible, but that their incubation periods are so long that most carriers will die of another cause before falling ill with CJD.

http://www.timesonline.co.uk/tol/life_and_style/health/article3123592.ece


Second wave of deaths feared from new type of CJD which killed womanCommentFEARS of a new wave of deaths caused by the human form of mad cow disease have been raised by a type of variant CJD not seen before.

Scientists who examined the brain of a 39-year-old woman killed by the disease found unusual patterns of damage.

The woman also had a distinct genetic make-up associated with her illness not shared by other victims.

advertisementInvestigations are at an early stage, but the findings point to the possibility of a new group of people succumbing to vCJD as a result of eating infected beef in the 1980s.

The disease, linked to misshapen prion proteins in the brain, has varying incubation periods according to genetic make-up.

Experts believe for many of those infected the timer could still be ticking. They might not develop symptoms for decades after acquiring the disease, or die from other causes before becoming ill. In some cases the incubation period might exceed 50 years.

VCJD arose in cattle as bovine spongiform encepha- lopathy (BSE) before appearing in a new form in humans. The incurable disease leaves the brain riddled with holes, like a sponge, causing a loss of mental faculties and death.

Since the disease was recognised in 1995 there have been 162 confirmed or suspected deaths in the UK.

Fears of an epidemic involving hundreds of thousands of deaths abated after the number of annual deaths peaked at 28 in 2000 and then quickly fell. In the year up to November 30, 2007 there were just four definite or probable cases.

All these people had the MM version of the gene that makes prions, which is carried by around 40% of the population.

The woman recently examined by scientists at the Medical Research Council's Prion Unit at University College London had a different gene variant, known as VV, found in about 10% of Britons. She could be the first of a new wave of cases with the same genetic make-up who have only now reached the end of their incubation period, say researchers.

Another possibility is that the woman simply had a rare form of "sporadic" CJD which has nothing to do with mad cows or infected beef.

The case was described in the journal Archives of Neurology and reported today in New Scientist magazine.

Dr Simon Mead, from the MRC Prion Unit, who examined the woman's brain, said: "The final conclusion remains open. It is waving the flag for neurologists to watch for other cases."

The case of the woman appears to be more similar to vCJD than sporadic CJD. She was relatively young, whereas most cases of sporadic CJD occur in people over 50, and the abnormal prions were typical of vCJD, not sporadic CJD.

The patterns of damage to her brain did not correspond either to MM cases of vCJD or the sporadic disease. This is to be expected, said the scientists, because the prion gene variant affects the brain damage seen in both humans and animals with the disease. It could be that people with the VV gene variant are next in the queue to fall victim to the disease after those with the MM variant.

A similar pattern was seen with kuru, a similar prion-related brain disease, which affected cannibals in Papua New Guinea.


http://www.theherald.co.uk/news/news/display.var.1938810.0.Second_wave_of_deaths_feared_from_new_type_of_CJD_which_killed_woman.php

Creutzfeldt-Jakob Disease, Prion Protein Gene Codon 129VV, and a Novel PrPSc
Type in a Young British Woman
Simon Mead, PhD, MRCP; Susan Joiner, MSc; Melanie Desbruslais, BSc; Jonathan
A. Beck, BSc; Michael O’Donoghue, PhD; Peter Lantos, FRCP; Jonathan D. F.
Wadsworth, PhD; John Collinge, FRS


Arch Neurol. 2007;64(12):1780-1784.

Background Variant Creutzfeldt-Jakob disease (vCJD) is an acquired prion
disease causally related to bovine spongiform encephalopathy that has
occurred predominantly in young adults. All clinical cases studied have been
methionine homozygotes at codon 129 of the prion protein gene (PRNP) with
distinctive neuropathological findings and molecular strain type (PrPSc type
4). Modeling studies in transgenic mice suggest that other PRNP genotypes
will also be susceptible to infection with bovine spongiform encephalopathy
prions but may develop distinctive phenotypes.

Objective To describe the histopathologic and molecular investigation in a
young British woman with atypical sporadic CJD and valine homozygosity at
PRNP codon 129.

Design Case report, autopsy, and molecular analysis.

Setting Specialist neurology referral center, together with the laboratory
services of the MRC [Medical Research Council] Prion Unit.

Subject Single hospitalized patient.

Main Outcome Measures Autopsy findings and molecular investigation results.

Results Autopsy findings were atypical of sporadic CJD, with marked gray
and white matter degeneration and widespread prion protein (PrP) deposition.
Lymphoreticular tissue was not available for analysis. Molecular analysis of
PrPSc (the scrapie isoform of PrP) from cerebellar tissue demonstrated a
novel PrPSc type similar to that seen in vCJD (PrPSc type 4). However, this
could be distinguished from the typical vCJD pattern by an altered protease
cleavage site in the presence of the metal ion chelator EDTA.

Conclusions Further studies will be required to characterize the prion
strain seen in this patient and to investigate its etiologic relationship
with bovine spongiform encephalopathy. This case illustrates the importance
of molecular analysis of prion disease, including the use of EDTA to
investigate the metal dependence of protease cleavage patterns of PrPSc.


Author Affiliations: MRC [Medical Research Council] Prion Unit and
Department of Neurodegenerative Disease, Institute of Neurology, University
College London, National Hospital for Neurology and Neurosurgery, London,
England (Drs Mead, Wadsworth, and Collinge; Mss Joiner and Desbruslais; and
Mr Beck); and Institute of Psychiatry, King's College London (Dr Lantos). Dr
O’Donoghue is now with the Department of Clinical Neurology, Nottingham
University Hospitals NHS [National Health Service] Trust, Nottingham,
England.

http://archneur.ama-assn.org/cgi/content/short/64/12/1780


Monitoring the occurrence of emerging forms of Creutzfeldt-Jakob disease in
the United States

http://cjdusa.blogspot.com/

http://creutzfeldt-jakob-disease.blogspot.com/


CJD QUESTIONNAIRE

http://cjdquestionnaire.blogspot.com/

TSS





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