A bi-allelic nucleotide change in the CST3 gene was successfully introduced in both induced pluripotent stem cells (iPSCs) and a human retinal pigment epithelium cell line (ARPE-19) generating isogenic cells homozygous for variant B cystatin C, a recessive allele associated with increased risk of developing age-related macular degeneration and Alzheimer’s disease11,12. Here, CST3 is linked to age-related macular degeneration.