First, we assume that IS/OS junction loss is correlated with photoreceptor loss and/or dysfunction;15,17 that hypo–SW-AF or absent SW-AF in STGD1 represents RPE loss and/or atrophy; that hyper–SW-AF can be attributed to accelerated bisretinoid production from degenerating photoreceptor cells; and that it is associated with RPE cells being absent or with thinning and dysfunctional RPE.13,36 Second, our SW-AF results indicated that the area of abnormal AF was significantly larger than the hypo- or absent AF area, and that it included the area of IS/OS junction loss. The gene discussed is ABCA4; the disease is atrial fibrillation.