Olfaction in Parkin single and compound heterozygotes in a cohort of young onset Parkinson's disease patients. - Malek N; Swallow DM; Grosset KA; Lawton MA; Smith CR; Bajaj NP; Barker RA; Ben-Shlomo Y; Bresner C; Burn DJ; Foltynie T; Morris HR; et al. (Acta neurologica Scandinavica, 2016)