Oosterloo M, Touze A, Byrne LM, Achenbach J, Aksoy H, Coleman A, Lammert D, Nance M, Nopoulos P, Reilmann R, Saft C, Santini H, Squitieri F, Tabrizi S, Burgunder JM, Quarrell O; Pediatric Huntington Disease Working Group of the European Huntington Disease Network.