Creutzfeldt-Jakob disease (CJD) is a rare, rapidly progressive, invariably fatal brain disorder primarily characterized
by mental deterioration, although motor problems can be significant in many cases.
CJD belongs to a group of human and animal diseases known as transmissible spongiform
encephalopathies (TSE) or prion diseases. Spongiform refers to the characteristic
appearance of infected brains, which become filled with holes until they resemble
sponges under a microscope. Typically, onset of symptoms occurs at about age 60 and
runs a rapid course. There are four major categories of CJD: sporadic CJD, hereditary
CJD, acquired or iatrogenic CJD, and variant CJD.
Sporadic CJD is the most common form of the disease. It accounts for 85% of cases. The cause of
sporadic CJD is unknown, but it is believed that a normal cellular protein undergoes
a spontaneous change in conformation (prion protein) that results in the disease.
This form of the disease is believed to be spontaneous and not the result of an infection.
Hereditary or familial CJD is a very uncommon disease and the consequence of a mutation in the gene that encodes
the prion protein. About 5 to 10 percent of cases of CJD in the United States are
Acquired or Iatrogenic CJD is also very rare accounting for less than 1% of cases. It results from the accidental
transmission during the course of medical interventions. Examples include transmission
in cases of corneal transplantation, dural grafts, or treatment with Human Growth
Hormone isolated from cadaveric pituitary glands.
Variant CJD was first reported in 1996. It is believed to be the result of eating meat from cattle
with bovine spongiform encephalopathy (BSE or mad cow disease). In contrast with sporadic
CJD which affects older people, the variant form primarily affects young subjects
(i.e., in the late 20s) and may have a longer course, between one and two years.