GUCA1A and central areolar choroidal dystrophy: CACD is a special form of IRD that mainly affects the maculae and is characterized by a well-defined atrophic region of retinal pigment epithelium (RPE) and choriocapillaris at the latest stage.7,8,9 Before our study, mutations in two other genes, peripherin-2 (PRPH2; MIM 179605) and GUCY2D, were implicated in CACD etiology.8,10,11,12 We also found that diverse pathogenic mechanisms of GUCA1A mutations might correlate with the phenotypic diversity of IRDs.