SYNJ1 and Parkinson disease: To date, 34 patients originating from 20 families with biallelic SYNJ1 missense, nonsense, frameshift, or splicing mutations have been reported to constitute a heterogeneous multitude of phenotypes ranging from EOPD or atypical parkinsonism (13 families) up to severe epileptic encephalopathies without parkinsonism (seven families) [42,211,212,213,214,215,216,217,218,219,220,221,222,223,224].