The third hallmark of the EEC syndrome is orofacial clefting, in particular lip and palate. p63 mutations also cause the other five inherited syndromes: symptoms are overlapping, but each of these diseases has its own characteristic phenotypic features: for instance AEC syndrome (ankyloblepharon-ectodermal defects-cleft lip/palate) has as distinctive feature ankyloblepharon, while mammary glands and nipples hypoplasia are frequent findings in LMS syndrome and in ADULT syndrome (acro-dermato-ungual-lacrimal-tooth syndrome).
Here, we characterize the transcriptional activity and protein stability of ΔNp63 mutants (that is, mutants of a p63 isoform that lacks the N-terminal transactivation domain) that are found in ectrodactyly-ectodermal dysplasia-cleft syndrome (EEC), ankyloblepharon-ectodermal dysplasia-clefting syndrome (AEC) and nonsyndromic split-hand/split-foot malformation (SHFM).
In this paper we describe a 17-year-old girl affected by ectrodactyly-ectodermal dysplasia-clefting syndrome with a de novo p63 mutation that predicts a heterozygous missense substitution (arginine to tryptophan substitution caused by a cytosine to thymine transition) at the amino acid 304 (R304W) of the p63 DNA-binding domain.
This report expands the knowledge of genotype-phenotype data on the p63 gene and suggests there may be a considerable overlap between the EEC syndrome and the ADULT syndrome.
Mutations in the p63 gene are found in a number of human syndromes, including ectrodactyly-ectodermal dysplasia-cleft lip/palate (EEC) syndrome, limb-mammary syndrome (LMS), Hay-Wells syndrome and in non-syndromic split-hand/split-foot malformation (SHFM).
Germline mis-sense mutations in the DNA-binding domain of the p63 gene have recently been established as the molecular basis for the autosomal dominant EEC (Ectrodactyly, Ectodermal dysplasia, Clefting) syndrome.
The two amino acids mutated in the families with SHFM appear to be primarily involved in maintenance of the overall structure of the domain, in contrast to the p63 mutations responsible for EEC syndrome, which reside in amino acid residues that directly interact with the DNA.