progressive supranuclear palsy-progressive non-fluent aphasia syndrome (MONDO_0016564) can be described as follows. PSP-progressive non fluent aphasia (PSP-PNFA) is an atypical variant of progressive supranuclear palsy (PSP), a rare late-onset neurodegenerative disease. Unlike classic PSP (Richardson syndrome) patients present with an isolated speech production problem years before developing other motor features of PSP. Also known as: PSP-AOS, PSP-PNFA, progressive supranuclear palsy-apraxia of speech syndrome.