Since two of the PTCs implicated in JEB were also found in AI, and given the unconfirmed report of one of the same variants in an ERED case, it therefore seems likely that AI and ERED due to heterozygous COL17A1 pathogenic variants is caused, at least in some cases, by haploinsufficiency. This evidence concerns the gene COL17A1 and epithelial recurrent erosion dystrophy.