Reproductive factors and Parkinson's disease: A multicenter case-control study

ABSTRACT
Background: Given the overlap between Parkinson’s
disease and essential tremor, we examined genetic variants
in a-synuclein (SNCA) as risk determinants for
essential tremor.
Methods: Samples from 661 essential tremor subjects
and 1316 control subjects from 4 participating North
American sites were included in this study. Parkinson’s
disease samples (n 5 427) were compared against controls.
Twenty variants were selected for association analysis
within the SNCA locus. Individual logistic regression
analyses against essential tremor diagnosis were run for
each variant and then combined using meta-analysis.
Results: Our results do not show a significant association
between variants in the SNCA locus and risk of
essential tremor, whereas the established association
of SNCA variants with Parkinson’s disease risk was
observed.
Conclusions: Whereas genetic factors are likely to
play a large role in essential tremor pathogenesis, our
results do not support a role for common SNCA
genetic variants in risk for essential tremor.