Table 1.
Idiopathic Parkinson disease (IPD) versus GBA-related Parkinson disease. Whether or not GBA-related PD presents a truly unique phenotype is the subject of debate. Most of the time, patients with PD due to GBA mutations are clinically indistinguishable from IPD patients; however, in large cohorts, patients with GBA-related PD as a group do seem to differ from IPD patients as a group. The epidemiological and individual clinical relevance of these differences, in terms of prognosis, management, and treatment outcomes, remains to be determined.
| Feature | IPD | GD1-PD | GBA-PD Severe mutations | GBA-PD Mild mutations |
|---|---|---|---|---|
| Clinical Findings | ||||
| Average age of onset | Late 50s-early 60s | Possibly younger than IPD & GBA-PD, but not well defined. | Possibly younger than IPD & GBA-PD w/mild mutations (mean 55.7 years [8]) | Possibly younger than IPD (mean 57.9 years [8]) |
| Levodopa response | ++ | +/− | ++/− | ++/− |
| Dyskinesias | variable | ? | Possibly higher than IPD | Possibly higher than IPD |
| Prominent early cognitive impairment | − | +/− | +/− | +/− |
| Psychosis | + < − | +/− | +/− | +/− |
| Depression | +/− | ++/− | ++/− | ++/− |
| Olfactory dysfunction | + | + | + | + |
| Pathology | ||||
| Loss of pigmented cells in SNc | + | + | + | + |
| SN Lewy bodies | + | + | + | + |
| Cortical Lewy bodies | +/− | ++/− | ++/− | ++/− |
| Imaging | ||||
| SNc hyperechogeniticy on TCS | + | + | + | + |
| Midline raphe hypoechogenicity on TCS | +/− | ++/− | ++/− | ++/− |
| Presynaptic DA dysfunction on PET | + | + | + | + |
Key to abbreviations: IPD = idiopathic Parkinson disease; GD1 = Gaucher disease type 1; SN = substantia nigra, pars compacta; TCS = transcranial sonography; DA = dopamine’ PET = positron emission tomography.