SNCA and neurodegenerative disease: Identification of α-synuclein-positive glial cytoplasmic inclusions as a neuropathologic hallmark provided the first clue that abnormal protein accumulation is involved in the development of MSA.5 Furthermore, it suggested a link to other neurodegenerative diseases that are characterized by α-synuclein deposition, commonly referred to as synucleinopathies.