SPONGIFORM ENCEPHALOPATHIES
I first heard about spongiform encephalopathies about 10 years ago when there was a documentary about Mad cow disease, thanks to discovery channel of course. I wasn't even a medical student at the time but I did a bit of reading on the topic at that time. Well here's the gist about it...
A prion disease
It encompasses a Group of Disorders
It encompasses a Group of Disorders
Uncommon
A Prion is NOT an organism but a PROTEIN, DEVOID of DNA/RNA (nucleic acids), where the disease results from an accumulation of abnormally folded normal prion proteins. Founded by Dr Stanley Prusiner & awarded the 1997 Nobel Prize for Medicine and Physiology as a result.The gene for Prions is coded on chromosome 20.
02 forms of disease are observed;
A Prion is NOT an organism but a PROTEIN, DEVOID of DNA/RNA (nucleic acids), where the disease results from an accumulation of abnormally folded normal prion proteins. Founded by Dr Stanley Prusiner & awarded the 1997 Nobel Prize for Medicine and Physiology as a result.The gene for Prions is coded on chromosome 20.
02 forms of disease are observed;
Human forms - Creutzfeldt-Jakob disease, Kuru, GSS and Fatal Familial Insomnia
Animal forms - Scrapie, Wasting disease of elk/mule deer and Mad cow disease
You need to know that;
The normal prion protein designated - PrPc is expressed in high quantities in neurons, where the function remains unknown. When this protein undergoes a CONFORMATIONAL change in to PrPSc which is structurally abnormal, it consequently triggers other normal prion proteins to change in structure.
You need to know that;
The normal prion protein designated - PrPc is expressed in high quantities in neurons, where the function remains unknown. When this protein undergoes a CONFORMATIONAL change in to PrPSc which is structurally abnormal, it consequently triggers other normal prion proteins to change in structure.
The disease manifests in 3 possible ways;
GENETIC - autosomal dominant disorders (GSS, FFI & 15% of CJD) ; inheritance of a PrP gene encoding a form of PrPc which undergoes spontaneous conformational changes to PrPSc at a very high rate.
SPORADIC - Sporadic CJD is the commonest form of the human spongiform encephalopathies, where sporadic mutations of the PrP gene give rise to slow and spontaneous changes of the normal prion protein.
INFECTIOUS - Through the transmission or inoculation by a modified prion protein sample (grafts - cornea, depth electrodes or pituitary growth hormone treatment).
Pathology
Extensive vacuolation is observed within the connective tissue of the brain hence the name "spongiform".
Macroscopically ; Gross Atrophy
Microscopically ; Vacuoles are observed in the neuropil and cell bodies, in the gray matter. This is what it would look like, curtsy of my art work...
But do follow up on these links to look up what they look like under the microscopically;
Clinically;
You observe; Nonspecific changes which are followed by ataxia, tremor, dementia etc.
Check out this video on a woman suffering from kuru http://www.macalester.edu/psychology/whathap/UBNRP/tse10/Kuru.html
Investigations;
EEG - 1-2 Hz triphasic sharp waves + periodic complexes
Lumbar puncture - High PROTEIN (14-3-3)
Biopsy - Confirmatory, but not everyone does it
There is no curative treatment for the disorder, supportive measures are all that is possible.
