Color Discrimination in Patients with Gaucher Disease and Parkinson Disease

Background: Poor color discrimination among patients with Parkinson disease (PD) has long been recognized. It has been shown that carrying one or two mutations in the beta-glucocerebrosidase gene (GBA) for the autosomal disease Gaucher disease (GD), as based initially on clinical evidence, is a genetic risk factor for early-onset PD. Objective: The purpose of this study was to assess color discrimination in patients with one or two GBA mutations relative to healthy controls to ascertain whether this function is affected when persons with GD or even one GBA mutation develop PD. Methods: The Farnsworth-Munsell 100 hue test (FMHT) was evaluated among patients with GD+PD compared to patients with GD only, obligate GBA carriers with and without PD, patients with PD only, and healthy controls. FMHT outcome include computer-generated TES (Total Error Score) and values recommended by Vingrys & King-Smith. Results: Six groups of 10 persons were tested. Significant differences were seen for male GD+PD and for age in PD. The highest mean TES was in the PD only group, the lowest in the GD only group. There was a significant difference because of PD in groups with GD and GBA carriers. GD+PD means were between GD only and PD only mean scores. Conclusions: These findings confirm that PD impacts color discrimination, more in males with GD+PD but nonetheless, GD+PD patients (but not GBA carriers) had better scores than PD only patients.