Variably Protease-Sensitive Prionopathy (VPSPr)
(See also Overview of Prion Diseases.)
Variably protease-sensitive prionopathy was identified in 2008. It accounts for about 3% of all prion diseases in people and affects about 1 to 2 of every 100 million people. It typically develops around age 70, and life expectancy is about 24 months after symptoms develop.
Researchers have not identified any gene mutation that causes this disease. But variably protease-sensitive prionopathy is considered different from other prion disease because in it, enzymes called proteases can break the prions down more easily than occurs in other prion diseases.
At first, people with variably protease-sensitive prionopathy usually have changes in mood and behavior. They may lose their inhibitions, have intense feelings of well-being (euphoria), lose interest in their usual activities, or become listless. They may have problems speaking and may become uncoordinated. Mental function is impaired. Walking eventually becomes difficult.
Variably protease-sensitive prionopathy is especially difficult to diagnose and is often mistaken for another dementia.
There is no effective treatment for variably protease-sensitive prionopathy. Treatment focuses on relieving symptoms.