Which are the causes of Creutzfeldt Jakob Disease?

Creutzfeldt-Jakob Disease (CJD) is a rare and fatal neurodegenerative disorder that affects the brain. It belongs to a group of diseases known as transmissible spongiform encephalopathies (TSEs), which are characterized by the accumulation of an abnormal form of a protein called prion in the brain.

The exact cause of CJD is not fully understood, but there are several factors that can contribute to its development. The most common causes of CJD include:

1. 
   Spontaneous Mutation: In most cases, CJD occurs spontaneously without any known cause. It is believed to be caused by a spontaneous mutation in the PRNP gene, which provides instructions for the production of the prion protein. This mutation leads to the production of an abnormal prion protein that accumulates in the brain, causing damage to nerve cells.
   


2. 
   Inherited Genetic Mutation: In some cases, CJD can be inherited from a parent who carries a mutated PRNP gene. This is known as familial or genetic CJD. The mutated gene is passed down through generations, increasing the risk of developing the disease. However, inherited CJD accounts for only a small percentage of all cases.
   


3. 
   Exposure to Contaminated Tissue: Another rare cause of CJD is exposure to contaminated tissue, particularly through medical procedures. This can occur if surgical instruments or medical devices are not properly sterilized, allowing the transmission of abnormal prion proteins from an infected individual to a healthy one. However, such cases are extremely rare.
   


4. 
   Variant CJD: Variant CJD (vCJD) is a distinct form of the disease that is believed to be caused by consuming meat from cattle infected with bovine spongiform encephalopathy (BSE), commonly known as "mad cow disease." The abnormal prion protein from infected cattle can be transmitted to humans through the consumption of contaminated beef products. However, vCJD is extremely rare and has been mostly limited to a few countries.
   

It is important to note that CJD is not contagious in the usual sense. It cannot be spread through casual contact or airborne transmission. The transmission of CJD is primarily associated with direct exposure to infected brain tissue or consumption of contaminated meat in the case of vCJD.

In conclusion, the causes of Creutzfeldt-Jakob Disease can vary, including spontaneous mutations, inherited genetic mutations, exposure to contaminated tissue, and consumption of contaminated meat. While the exact cause may differ, all forms of CJD involve the accumulation of abnormal prion proteins in the brain, leading to the progressive degeneration of nerve cells and the onset of neurological symptoms.