As part of the LIPAD study , this work aims to identify potential environmental modifiers of the penetrance of LRRK2 pathogenic variants through the analysis of household dust of four groups of participants: PD+/LRRK2+ (PD individuals with pathogenic LRRK2 variants), PD-/LRRK2+ (individuals with pathogenic LRRK2 variants but without PD diagnosis), iPD (PD of unknown cause), and a matched control group (individuals without pathogenic variants and without PD diagnosis), through different metabolomics/exposomics and metagenomics approaches. This was complemented with non-target metabolomics on paired serum samples, where available, to investigate potential metabolomic differences between groups that could be attributed to environmental exposures.