Parkinson's disease, CYP2D6 polymorphism, and age.

Area of Science:

• Neuroscience
• Genetics
• Pharmacology

Background:

• Parkinson's disease (PD) may stem from genetic susceptibility to neurotoxins.
• The CYP2D6 gene is a candidate for PD due to its role in drug and toxin metabolism.
• Previous association studies on CYP2D6 and PD have yielded inconsistent results.

Purpose of the Study:

• To investigate the association between the CYP2D6*4 allele (poor metabolizer phenotype) and age of onset in Parkinson's disease.
• To clarify inconsistencies in previous genetic association studies related to PD.

Main Methods:

• A cohort of 576 PD patients and 247 controls underwent standard diagnostic, genotyping, and statistical analyses.
• Genotyping focused on the CYP2D6*4 allele.

Main Results:

• The CYP2D6*4 allele was not associated with earlier age at onset in PD patients.
• A higher frequency of the *4 allele was observed in late-onset PD, but this was attributed to an age-related increase in *4 frequency, not PD itself.
• CYP2D6*4 allele frequency increased significantly with advancing age in both PD patients and controls.

Conclusions:

• The CYP2D6*4 allele is not a risk factor for earlier onset of Parkinson's disease.
• The *4 allele may potentially be associated with survival in PD patients.
• Unrecognized age effects may explain the inconsistent findings in prior allelic association studies of PD.