Olfactory identification in LRRK2 G2019S mutation carriers: a relevant marker?

Area of Science:

• Neurology
• Genetics
• Olfactory Research

Background:

• Olfactory impairment can precede Parkinson disease (PD) development by years.
• Its predictive value may increase in individuals with genetic mutations, particularly for LRRK2-related PD.

Purpose of the Study:

• To evaluate olfactory identification as a marker for LRRK2-related Parkinson disease (PD).
• To compare olfactory performance across different genetic and idiopathic PD groups.

Main Methods:

• Olfactory identification was assessed in LRRK2 G2019S mutation carriers with PD, nonmanifesting carriers, idiopathic PD patients, noncarrier family members, and controls.
• Statistical comparisons and mixture modeling were used to analyze olfactory performance and identify subgroups.

Main Results:

• LRRK2 PD patients showed better olfactory scores than idiopathic PD patients.
• Both PD groups had significantly worse olfaction than controls.
• Fewer LRRK2 PD patients were hyposmic compared to idiopathic PD patients.
• Mixture modeling revealed subgroups with poor olfactory identification in both LRRK2 PD and nonmanifesting carriers.

Conclusions:

• Olfactory deficit is less consistently observed in LRRK2 PD compared to idiopathic PD.
• Some LRRK2 carriers may develop PD without prior olfactory impairment, suggesting alternative phenoconversion pathways.