B3GALT4 and Parkinson disease: There was a significant decrease in B3GALT4 expression in residual neuromelanin-containing cells in the SN of PD patients (7.5 ± 0.9 dots/cell, n = 7) compared to neurologically normal controls (17.1 ± 1.4 dots/cell, n = 8) (t = 5.293, df = 14, P = 0.0001) (Fig 2A and 2B).