Rapp Hodgkin syndrome (RHS) and Hay Wells syndrome (HWS) were initially named after the physicians who first described the disorders in the literature in 1968 and 1976, respectively. Both pairs of physicians described an ectodermal dysplasia characterized by hair, nail, limb, and tooth abnormalities, as well by facial clefts. The only difference between the ectodermal dysplasias described by Drs. Hay and Wells and by Drs. Rapp and Hodgkin was the presence of ankyloblepharon, meaning fused eyelids, in HWS patients but not in RHS patients. This difference was believed to be of clinical and diagnostic relevance, and thus, HWS and RHS were historically classified as two different ectodermal dysplasias.
However, even though this distinction was made, patients diagnosed with HWS did not always display ankyloblepharon, and it was often difficult, if not impossible, to distinguish HWS from RHS patients. Because of the striking overlap in clinical symptoms, many clinicians and scientists have long suspected that HWS and RHS might represent the same disorder, and that the presence or absence of certain features simply reflected the variability between patients. When genetic testing became available, this suspicion was confirmed by the finding that HWS and RHS were both caused by mutations in the same domain of the p63 gene. Even more strikingly, identical p63 gene mutations have been detected in patients diagnosed with either HWS or RHS. Consequently, these ectodermal dysplasias are now considered the same disorder, which is now referred to as Ankyloblepharon Ectodermal Dysplasia and Clefting (AEC).