LRRK2 and Parkinson disease: However, these data are recent and while others have begun to link prodromal PD phenotypes to particular microbiome compositions [22], to our knowledge, no study to date has followed the microbiome of at-risk individuals, for instance with known genetic links (e.g. LRRK2, SNCA) or phenotypes (e.g. RBD, IBD) through conversion to PD diagnosis.