Rapp-Hodgkin Syndrome (RHS) is a genetic disorder resulting from mutations in the TP63 gene encoding p63 transcription factor. p63 is directly associated with a cis-regulatory element on chromosome 7q21 that controls the expression of DLX5 and DLX6 genes which are involved in craniofacial abnormalities and ectrodactyly or split hand/foot malformation (SHFM).
However, AEC and RHS mutations in the 5' and 3' ends of the p63 gene point towards a critical role of the DeltaNp63alpha isoform for the AEC/RHS phenotype.
Missense mutations in the 3' end of the p63 gene are associated with either RHS (Rapp-Hodgkin syndrome) or AEC (Ankyloblepharon Ectodermal defects Cleft lip/palate) syndrome.
We report a new point mutation in the p63 gene in a family in which the mother was initially diagnosed with Rapp-Hodgkin syndrome and her two offspring manifested ankyloblepharon, ectodermal defects, cleft lip and palate, syndrome.
The expanding p63 mutation database demonstrates that there is considerable overlap between the molecular pathology of RHS and Hay-Wells syndrome, with identical mutations in some cases, and that these two disorders may in fact be synonymous.
Very recently, mutations in p63 have been identified as a cause of RHS; to date five such mutations have been identified.We describe a Thai girl with RHS.
The expanding p63 mutation database demonstrates that there is overlap between Rapp-Hodgkin syndrome and several other ectodermal dysplasia syndromes, notably Hay-Wells syndrome, and that characterization of the functional consequences of these p63 gene mutations at a molecular and cellular level is likely to provide further insight into the clinical spectrum of these developmental malformation syndromes.
Collectively, these investigations demonstrate that RHS is also caused by mutations in p63 and that the clinical similarities to AEC syndrome are paralleled by the nature of the inherent mutation.