GRIN2B and Parkinson disease: The strengths of this study include the following: (1) demonstrating a novel association between the GRIN2B rs219882 G allele and PD susceptibility and age of onset in a Chinese population and (2) being the first to discover that GRIN2B GG + GT carriers experience rapid motor progression, characterized by more severe rigidity and axial impairment, in a longitudinal study of PD patients from China.