A paradoxical relationship between family history, onset age, and genetic risk in Parkinson's disease. Issue 2 (28th November 2018) - Kristiansen, Madeleine; Maple‐Grødem, Jodi; Alves, Guido; Arepalli, Sampath; Hernandez, Dena G.; Iwaki, Hirotaka; Nalls, Mike A.; Singleton, Andrew; Tysnes, Ole‐Bjørn; Toft, Mathias; Pihlstrøm, Lasse