Everyone carrys the LRRK2 gene. The question is whether your version is mutated. If you are 'GG' for the rs34637584 SNP in the LRRK2 gene, then you have the 'normal' version of the gene and NOT the mutation linked to PD. If one were 'GA' or 'AA' that would be heterozygous or homozygous, respectively, for the PD-associated mutation.

While 23andMe reports on other PD genetic variants (SNCA, GBA or MAPT) it is important to realize that the service doesn't represent the full set of known potential variants. Remember, SNP analyses in general inform us about common mutations for common diseases. Since PD genetic risk factors are still rare, the SNP chips don't analyze all known PD mutations. So, technically, even being 'negative' on the four variants covered in the service doesn't mean your PD doesn't have a genetic component.

I know that interpreting this data is complex (I just checked this information with one of our PhD's at MJFF). I hope you find this explanation helpful.

Debi