Objective: To investigate the role of the GBA mutation in smelling perception in PD patients and healthy subjects.

Background: Hyposmia is a non-specific sign associated with Parkinson’s disease (PD). We aimed to study differences in smelling perception between PD patients and non-parkinsonian carriers of the GBA1 (single or double mutation).

Method: A brief smell identification test (BSIT) version A was performed in consecutive PD patients attending routine follow-up visits at the Movement Disorders Unit, and of GBA1 carriers who participated in a previous study. Demographic data was recorded, including age and gender, as well as UPDRS, and other non-motor complaints for all participants, and of disease duration for the PD patients.

Results: 112 participants were enrolled, 30 healthy participants with no GBA1 mutation (HC), 24 Non-GBA1 PD patients (NGPD), 18 GBA1-PD, 20 Gaucher patients and 20 GBA1 carriers (the last two were grouped together as H-GBA1).

GBA1-PD and NGPD had the lowest BSIT scores, with 4.3±3.5 and 4.7±3.0 average correct answers, respectively, versus HC and H-GBA1, answering 9.9±1.8 and 9.0±2.6 correct answers, respectively; with  p<0.001 between the PD and non-PD groups.

Eight of the 12 smells tested (cherry, clove, leather, strawberry, pineapple, smoke, lemon, natural gas and rose) were significantly abnormal in the 2 PD groups compared to the H-GBA and HC groups (p<0.001) in addition for the lilac smell was p=0.002.

Conclusion: The rate of hyposmia is highest in patients with PD. GBA1 variants per se do not seem to have impact on smell perception.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/contrasting-olfactory-perception-in-parkinsons-disease-impact-of-gba1-gene-mutations/