Prospects for gene-environment interactions in exfoliation syndrome.

Complex traits can be triggered by environmental factors in genetically predisposed individuals. The lysyl oxidase-like 1 gene (LOXL1) variants associated with exfoliation syndrome (XFS) are detected in >90% of cases that have been genotyped from sites around the world. Remarkably, roughly 80% of people without XFS also possess these same variants in all populations that have been tested. Nonetheless, the prevalence of XFS varies from ≤0.4% to >20%. These data suggest that other genetic variants, epigenetic modifications, or environmental factors also contribute to XFS. Furthermore, it is possible that environmental factors modify the association between LOXL1 and XFS. Interactions between LOXL1 variants and environmental factors could explain the varying prevalence of XFS seen throughout the world. At the very least, the discovery of the association between LOXL1 variants and XFS has opened the door to the discovery of environmental risk factors for this condition. Candidate gene-environment interactions in XFS will be discussed.