sentence: Genetic studies of PD have uncovered mutations in α - syn itself that result in the over-expression or misfolding of this major Lewy body component ( Polymeropoulos et al ., 1997 ; Kruger et al ., 1998 ; Singleton et al ., 2003 ; Zarranz et al ., 2004 ; Simon-Sanchez et al ., 2009 ) .