CST3 and age-related macular degeneration: In the present study, we have identified, for the first time to our knowledge, the interactome of WT cystatin C and AMD/AD-associated variant B cystatin C. The findings highlighted specific variant B cystatin C interacting mitochondrial proteins while also confirming the enrichment of variant B in mitochondrial fractions isolated from RPE cells expressing this form of the protein.