Primary progressive aphasia (PPA)
is a disorder characterized by language disturbance, including difficulty making or understanding speech (aphasia). In the early stages, PPA often causes difficulty with naming, word finding, or word comprehension. In later stages, affected people often become mute and lose their ability to communicate. PPA may sometimes be the initial manifestation of another neurodegenerative disease, such as frontotemporal dementia or Alzheimer disease. In some cases, PPA is caused by mutations in the GRN gene and is inherited in an autosomal dominant maner.
PPA can be classified into three distinct types which include progressive non-fluent aphasia (PNFA), semantic dementia (SD), and the logopenic variant (LPA). Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.