The present study revealed that the R243Q mutation in the TP63 gene produced a novel phenotype named SHFM4, thereby demonstrating the mutational overlap between ectrodactyly‑ectodermal dysplasia‑cleft syndrome and SHFM4.
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).
There was no relationship of limbal stem cell failure with the severity of EEC syndrome, as classified by the EEC score, or the underlying molecular defect in p63.
Here, we report a three-generation family with ADULT syndrome due to an R243W mutation in TP63, a mutation that has previously been described in one patient with ADULT syndrome and eight unrelated patients with EEC 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).
C308Y mutation in exon 8 of TP63 gene was detected, which was previously described to lead only to EEC syndrome and not to any of the other allelic conditions.
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.
Pathogenic mutations in the TP63 transcription factor have been identified as the molecular basis of EEC syndrome and to date 34 mutations have been reported.
The TP63 gene molecular study showed in both siblings a heterozygous H208D mutation, which has not been previously reported to our knowledge, suggesting that this molecular lesion is associated with EEC syndrome without orofacial clefting.
Of the six cases/families now reported with EEC syndrome and Arg227GlnTP63 mutation, four have manifested this distinct urological abnormality, indicative of a genotype-phenotype correlation.
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.