How can prion diseases be inherited, infectious, or sporadic?

Prion diseases, which are types of transmissible spongiform encephalopathies, are unique because they can manifest through three distinct pathways:

• Inherited: These cases arise from a mutation in the PRNP gene, which encodes the prion protein. This mutation is passed from parent to child in a dominant fashion, meaning only one mutated copy of the gene is required for the disease to occur.1
• Infectious (Acquired): Prions can act as infectious agents when transmitted to an organism. In humans, this occurs rarely through exposure to contaminated tissues or medical procedures, such as corneal transplants, contaminated surgical instruments, or the consumption of tissues infected with animal prions like those causing bovine spongiform encephalopathy.21
• Sporadic: This is the most common form of prion disease. It occurs at random, and the underlying molecular process remains unknown. Scientists hypothesize that the protein may misfold spontaneously or due to a mutation incurred as the body ages.21

Once present, prions multiply by inducing normal proteins to refold into the abnormal, disease-causing shape, leading to the accumulation of prions and the destruction of neurons.21