Molecular basis of EEC (ectrodactyly, ectodermal dysplasia, clefting) syndrome: five new mutations in the DNA-binding domain of the TP63 gene and genotype-phenotype correlation

A Family with EEC Syndrome in the Son and ADULT Syndrome in His Father Caused by the c.797G>A (p.Arg266Gln) Pathogenic Variant in the TP63 Gene

Introduction

To our knowledge, there are few examples of intrafamilial variability involving two different TP63-linked morphopathies within a same family. Here, we describe a Mexican family in which the son had ectrodactyly, ectodermal dysplasia, and cleft lip/palate syndrome 3 (EEC3), and his father acro-dermato-ungual-lacrimal-tooth (ADULT) syndrome, both heterozygous for the p.Arg266Gln pathogenic variant in TP63. Additionally, we reviewed the clinical information reported for this TP63 genotype.

Case Presentation

The son of this family presented ectodermal defects (thin and sparse hair, mild nail dysplasia), tetramelic ectrodactyly, syndactyly, and nasolacrimal duct obstruction (NLDO), indicative of an EEC3 diagnosis. His father, however, exhibited severe NLDO, facial freckling, dental abnormalities, mild nail dysplasia, and a history of micturition problems, compatible with ADULT syndrome. Both were heterozygous for the NM_003722.5(TP63):c.797G>A (p.Arg266Gln) pathogenic variant in TP63.

Discussion

This report expands the spectrum of intrafamilial variability confirming that this can include the expression of distinct types of TP63-related disorders among different members of the same family, whose implications should be also considered in genetic counseling. From our review, we observed that p.Arg266Gln variant seems to correlate particularly with the presence of NLDO, sparse hair/eyebrows, ridged/dystrophic nails, anodontia/hypodontia, and micturition difficulties, as well as for a minor frequency of cleft lip/cleft palate.

A newborn with ectrodactyly, tetralogy of Fallot, esophageal atresia, hypospadias and TP63 gene mutation: A new type of EEC Syndrome?

EEC syndrome is an autosomal dominant genetic disease with incomplete penetrance characterized by ectrodactyly, ectodermal dysplasia, and cleft lip/palate; these manifestations can differently occur in the affected subjects and can also be associated with other anomalies, such as in the urogenital tract.We reported the case of a newborn with prenatal diagnosis of EEC type 3 associated with severe cardiac abnormalities (Tetralogy of Fallot), high esophageal atresia with fistula and penoscrotal hypospadias.

Innovative Therapeutic Approaches for the Treatment of the Ocular Morbidities in Patients with EEC Syndrome

Ectrodactyly-Ectodermal dysplasia-Clefting (EEC) syndrome is caused by heterozygous missense point mutations in the p63 gene, an important transcription factor during embryogenesis and for stem cell differentiation in stratified epithelia. Most of the cases are sporadic, related to de novo mutations arising during early-stage development. Familial cases show an autosomic dominant inheritance. The major cause of visual morbidity is limbal stem cell failure, which develops in the second to third decade of life. Patients often show ocular surface alterations, such as recurrent blepharitis and conjunctivitis, superficial microlesions of the cornea, and spontaneous corneal perforation and ulceration, leading to progressive corneal clouding and eventually visual loss. No definitive cures are currently available, and treatments to alleviate symptoms are only palliative. In this review, we will discuss the proposed therapeutic strategies that have been tested or are under development for the management of the ocular defects in patients affected by EEC syndrome: (i) gene therapy-based approaches by means of Allele-Specific (AS) siRNAs to correct the p63 mutations; (ii) cell therapy-based approaches to replenish the pool of limbal stem cells; and (iii) drug therapy to correct/bypass the genetic defect. However, as the number of patients with EEC syndrome is too limited, further studies are still necessary to prove the effectiveness (and safety) of these innovative therapeutic approaches to counteract the premature differentiation of limbal stem cells.

Identification of a novel heterozygous missense TP63 variant in a Chinese pedigree with split-hand/foot malformation

BACKGROUND

Tumor protein p63 is an important transcription factor regulating epithelial morphogenesis. Variants associated with the TP63 gene are known to cause multiple disorders. In this study, we determined the genetic cause of split-hand/foot malformation in a Chinese pedigree.

METHODS

For this study, we have recruited a Chinese family and collected samples from affected and normal individuals of the family (three affected and two normal). Whole exome sequencing was performed to detect the underlying genetic defect in this family. The potential variant was validated using the Sanger sequencing approach.

RESULTS

Using whole-exome and Sanger sequencing, we identified a novel heterozygous pathogenic missense variant in TP63 (NM_003722.5: c.921G > T; p.Met307Ile). This variant resulted in the substitution of methionine with isoleucine. Structural analysis suggested a resulting change in the structure of a key functional domain of the p63 protein.

CONCLUSION

This novel missense variant expands the TP63 variant spectrum and provides a basis for genetic counseling and prenatal diagnosis of families with split-hand/foot malformation or other TP63-related diseases.

TP63-mutation as a cause of prenatal lethal multicystic dysplastic kidneys

Background

Ectrodactyly‐ectodermal dysplasia‐clefting syndrome 3 (EEC) is one of the six overlapping syndromes caused by mutations in the tumor protein p63 gene (TP63). EEC is suspected when patients have cleft hands or feet, polydactyly, and syndactyly, abnormal development of the ectodermally derived structures, and orofacial clefting. Genitourinary (GU) anomalies have been identified in patients with EEC, yet these are often under‐recognized and under‐reported. The available literature on sonographic prenatal findings is sparse, especially when considering GU anomalies.

Methods

We present the case of a male stillborn fetus, who was found antenatally to have multicystic dysplastic kidneys and anhydramnios. Following the termination of pregnancy, examination and autopsy further revealed unilateral polydactyly and bilateral syndactyly which had not been previously identified on antenatal ultrasound.

Results

Whole‐exome sequencing (WES) revealed a de novo heterozygous pathogenic variant in exon 5 of the TP63 gene: p.His247Arg: c.740A>G (NM_003722.4) which has been reported in the literature. The His247Arg variant has been published as a pathogenic variant in association with EEC, both with and without orofacial clefting.

Conclusion

Our prenatal case expands the phenotypic spectrum of TP63‐related disorders in general. In addition, it adds to the phenotype associated with the His247Arg pathogenic variant responsible for EEC. Further, we highlight the importance of WES as a postnatal tool to help clarify unexpected findings, and as a way to add to the spectrum of existing phenotypes of known single‐gene disorders.

Ectrodactyly-ectodermal dysplasia-clefting syndrome presenting with bilateral choanal atresia and rectal stenosis

We present the case of a male who shortly after birth developed acute respiratory distress due to bilateral choanal atresia, following which he was found to have rectal stenosis. Genetic testing for CHARGE syndrome was negative, but whole genome sequencing identified heterozygosity for a pathogenic missense variant in TP63 (c.727C > T, p.(Arg243Trp). He also has partial cutaneous syndactyly of the third and fourth fingers of the right hand, and bilateral lacrimal duct stenosis/aplasia. A later maxillofacial review identified a palpable submucousal cleft and his scalp hair is blond and slightly sparse. Choanal atresia and rectal stenosis are recognized features of ectrodactyly-ectodermal dysplasia-clefting syndrome, but we believe this is the first report of a case presenting with these features in the absence of the cardinal features.

A novel mutation (c.1010G>T; p.R337L) in TP63 as a cause of split-hand/foot malformation with hypodontia

BACKGROUND

Tumor protein p63 (TP63)-related disorders can be divided into at least six categories, including ectrodactyly-ectodermal dysplasia-cleft lip/palate syndrome 3 (EEC syndrome 3), ankyloblepharon-ectodermal defects-cleft lip/palate syndrome (AEC syndrome), acro-dermo-ungual-lacrimal-tooth syndrome (ADULT syndrome), limb-mammary syndrome (LMS), Rapp-Hodgkin syndrome (RHS) and split-hand/foot malformation 4 (SHFM4), and are all a result of heterozygous mutations of TP63. The phenotypes of TP63-related disorders broadly involve ectodermal dysplasias, acromelic malformation and orofacial cleft. SHFM and hypodontia are prominent clinical manifestations of TP63-related disorders.

METHODS

The present study investigated a family with SHFM and hypodontia; determined the sequences of DLX5, WNT8B, WNT10B, BHLHA9, CDH3, DYNC1I1 and FGFR1; and performed single nucleotide polymorphism-array analysis. We detected the mutation by multiple sequence alignments and a bioinformatic prediction.

RESULTS

We identified a novel missense mutation of TP63 (c.1010G>T; R337L) in the family without mutations of DLX5, WNT8B, WNT10B, BHLHA9, CDH3, DYNC1I1, FGFR1 and copy number variants causing SHFM.

CONCLUSIONS

A mutation of TP63 (c.1010G>T; R337L) leads to SHFM with hypodontia. The identification of this mutation expands the spectrum of known TP63 mutations and also may contribute to novel approaches for the genetic diagnosis and counseling of families with TP63-related disorders.

Prenatal diagnosis of fetal skeletal dysplasia using targeted next-generation sequencing: an analysis of 30 cases

Background

This study aims to provide genetic diagnoses for 30 cases of fetal skeletal dysplasia, and a molecular basis for the future prenatal diagnosis of fetal skeletal dysplasia.

Methods

A total of 30 cases of fetal skeletal dysplasia detected with ultrasound between January 2014 and June 2017 were analyzed. Among these fetuses, 15 fetuses had local skeletal malformations, while 15 fetuses had short limb malformations. Samples of fetal umbilical cord blood, amniotic fluid, and/or aborted tissue were collected from all cases. Karyotyping, whole genome sequencing, and targeted next-generation sequencing of skeletal disease-related pathogenic genes were performed, as needed. Blood samples were taken from the parents for verification using Sanger sequencing.

Results

Among the 30 cases of fetal skeletal dysplasia, two cases were diagnosed with trisomy 18. However, none of these cases were identified with any microdeletions or microreplications associated with skeletal dysplasia. Among the 28 chromosomally normal cases with fetal skeletal dysplasia, 21 cases were detected with mutations in genes related to skeletal diseases. Furthermore, collagen gene mutations were detected in six fetuses with short limb malformations, while heterozygous disease-causing mutations in the fibroblast growth factor receptor 3 (FGFR3) gene were detected in seven fetuses. The remaining fetuses carried mutations in other various genes, including tumor protein p63 (TP63), cholestenol delta-isomerase (EBP), cholinergic receptor nicotinic gamma subunit (CHRNG), filamin B (FLNB), and SRY-box 9 (SOX9). Three compound heterozygous mutations in CHRNG, COL11A2 and SOX9 were carried by phenotypically healthy parents.

Conclusion

Targeted next-generation sequencing can significantly improve the prenatal diagnoses of fetal skeletal dysplasia, providing parents with more precision medicine, and improved genetic counseling.

TP63 mutations are frequent in cutaneous melanoma, support UV etiology, but their role in melanomagenesis is unclear

In contrast to TP53, cancer development is rarely associated with mutations in the TP63 and TP73 genes. Recently, next generation sequencing analysis revealed that TP63 mutations are frequent, specifically in cutaneous melanomas. Cutaneous melanoma represents 4% of skin cancers but it is responsible for 80% of skin cancer related deaths. In the present study, we first determined whether all three members of the P53 family of transcription factors were found mutated in cutaneous melanomas by retrieving all TP53, TP63 and TP73 mutations from cBioPortal (http://www.cbioportal.org/). TP53 and TP63 were frequently mutated [15.0% (91/605) and 14.7% (89/605), respectively], while TP73 [1.5% (9/605)] was more rarely mutated (p<0.0001). A UV-mutation fingerprint was recognized for TP63 and TP73 genes. Then, we tried to evaluate the potential role of TP63 mutations as drivers or passengers in the tumorigenic process. In the former case, the amino acid substitutions should cause significant functional consequences on the main biochemical activity of the P63 protein, namely transactivation. The predicted effects of specific amino acid substitutions by two bioinformatics tools were rather different. Using a yeast-based functional assay, the observed hotspot mutant R379CP63 protein exhibited a substantial residual activity compared to the wild-type (>70%). This result does not support a major role of the mutant P63 protein in melanomagenesis while it is still consistent with the TP63 gene being a recorder of UV exposure. The TP63 mutation spectrum from cutaneous melanomas, when compared with that observed at the germinal level in patients affected by P63-associated diseases [ectodermal dysplasia syndromes, (EDs)], revealed significant differences. The TP63 mutations were more frequent at CpGs sites (p<0.0001) in EDs and at PyPy sites (p<0.0001) in cutaneous melanomas. The two spectra differed significantly (p<0.0001). We conclude that TP63 mutations are frequent in cutaneous melanoma, support UV etiology, but their role in melanomagenesis is unclear.

Genitourinary malformations: an under-recognized feature of ectrodactyly, ectodermal dysplasia and cleft lip/palate syndrome

The ectodermal dysplasia and cleft lip/palate (EEC) syndrome describes the association of ectrodactyly, ectodermal dysplasia and orofacial clefting. As with many autosomal dominant disorders, there is variability in expression and not all of these three core features are present in every individual with the condition. Moreover, there may be additional associated features, which are under-recognized. One of these is the presence of genitourinary anomalies, some of which cause significant morbidity. This report details a further two patients with EEC syndrome and genitourinary involvement, including flaccid megacystis with detrusor muscle failure, bilateral hydronephrosis and megaureter, requiring significant renal and urological involvement during their childhood. We go on to review the literature on the diagnosis and management of genitourinary malformations in EEC syndrome.

Tooth agenesis and orofacial clefting: genetic brothers in arms?

Tooth agenesis and orofacial clefts represent the most common developmental anomalies and their co-occurrence is often reported in patients as well in animal models. The aim of the present systematic review is to thoroughly investigate the current literature (PubMed, EMBASE) to identify the genes and genomic loci contributing to syndromic or non-syndromic co-occurrence of tooth agenesis and orofacial clefts, to gain insight into the molecular mechanisms underlying their dual involvement in the development of teeth and facial primordia. Altogether, 84 articles including phenotype and genotype description provided 9 genomic loci and 26 gene candidates underlying the co-occurrence of the two congenital defects: MSX1, PAX9, IRF6, TP63, KMT2D, KDM6A, SATB2, TBX22, TGFα, TGFβ3, TGFβR1, TGFβR2, FGF8, FGFR1, KISS1R, WNT3, WNT5A, CDH1, CHD7, AXIN2, TWIST1, BCOR, OFD1, PTCH1, PITX2, and PVRL1. The molecular pathways, cellular functions, tissue-specific expression and disease association were investigated using publicly accessible databases (EntrezGene, UniProt, OMIM). The Gene Ontology terms of the biological processes mediated by the candidate genes were used to cluster them using the GOTermMapper (Lewis-Sigler Institute, Princeton University), speculating on six super-clusters: (a) anatomical development, (b) cell division, growth and motility, (c) cell metabolism and catabolism, (d) cell transport, (e) cell structure organization and (f) organ/system-specific processes. This review aims to increase the knowledge on the mechanisms underlying the co-occurrence of tooth agenesis and orofacial clefts, to pave the way for improving targeted (prenatal) molecular diagnosis and finally to reflect on therapeutic or ultimately preventive strategies for these disabling conditions in the future.

Novel variant in the TP63 gene associated to ankyloblepharon-ectodermal dysplasia-cleft lip/palate (AEC) syndrome

BACKGROUND

Ankyloblepharon-ectodermal dysplasia-cleft lip/palate (AEC) syndrome is a disorder resulting from anomalous embryonic development of ectodermal tissues. There is evidence that AEC syndrome is caused by mutations in the TP63 gene, which encodes the p63 protein. This is an important regulatory protein involved in epidermal proliferation and differentiation.

MATERIALS AND METHODS

Genome sequencing was performed in DNA from peripheral blood leukocytes of a newborn with AEC syndrome and her parents. Variants were searched in all coding exons and intron-exon boundaries of the TP63 gene.

RESULTS

A heterozygous missense variant (NM_003722.4:c.1063G>C (p.Asp355His) was found in the newborn patient. No variants were found in either of the parents.

CONCLUSIONS

We identified a previously unreported variant in TP63 gene which seems to be involved in the somatic malformations found in the AEC syndrome. The absence of this variant in both parents suggests that the variant appeared de novo.

Recurrence of split hand/foot malformation, cleft lip/palate, and severe urogenital abnormalities due to germline mosaicism for TP63 mutation

We describe two sibling fetuses with urogenital abnormalities detected by prenatal ultrasound, in which post-delivery examination showed split hand and foot malformation, and bilateral cleft lip and palate. These findings are consistent with ectrodactyly-ectodermal dysplasia-cleft lip with or without cleft palate syndrome (EEC). Both fetuses were found to have the same missense mutation in TP63 (c.1051G > A; p.D351N). Parental clinical examinations and lymphocyte DNA analyses were normal. This report illustrates the potential severity of urogenital defects in TP63-related disorders, which may be detectable with fetal ultrasonography. It highlights the need to counsel for the possibility of germline mosaicism in TP63-associated disorders. © 2016 Wiley Periodicals, Inc.

Allele-specific silencing of EEC p63 mutant R304W restores p63 transcriptional activity

EEC (ectrodactily-ectodermal dysplasia and cleft lip/palate) syndrome is a rare genetic disease, autosomal dominant inherited. It is part of the ectodermal dysplasia disorders caused by heterozygous mutations in TP63 gene. EEC patients present limb malformations, orofacial clefting, skin and skin's appendages defects, ocular abnormalities. The transcription factor p63, encoded by TP63, is a master gene for the commitment of ectodermal-derived tissues, being expressed in the apical ectodermal ridge is critical for vertebrate limb formation and, at a later stage, for skin and skin's appendages development. The ΔNp63α isoform is predominantly expressed in epithelial cells and it is indispensable for preserving the self-renewal capacity of adult stem cells and to engage specific epithelial differentiation programs. Small interfering RNA (siRNA) offers a potential therapy approach for EEC patients by selectively silencing the mutant allele. Here, using a systemic screening based on a dual-luciferase reported gene assay, we have successfully identified specific siRNAs for repressing the EEC-causing p63 mutant, R304W. Upon siRNA treatment, we were able to restore ΔNp63-WT allele transcriptional function in induced pluripotent stem cells that were derived from EEC patient biopsy. This study demonstrates that siRNAs approach is promising and, may pave the way for curing/delaying major symptoms, such as cornea degeneration and skin erosions in young EEC patients.

Personalized Stem Cell Therapy to Correct Corneal Defects Due to a Unique Homozygous-Heterozygous Mosaicism of Ectrodactyly-Ectodermal Dysplasia-Clefting Syndrome

: Ectrodactyly-ectodermal dysplasia-clefting (EEC) syndrome is a rare autosomal dominant disease caused by mutations in the p63 gene. To date, approximately 40 different p63 mutations have been identified, all heterozygous. No definitive treatments are available to counteract and resolve the progressive corneal degeneration due to a premature aging of limbal epithelial stem cells. Here, we describe a unique case of a young female patient, aged 18 years, with EEC and corneal dysfunction, who was, surprisingly, homozygous for a novel and de novo R311K missense mutation in the p63 gene. A detailed analysis of the degree of somatic mosaicism in leukocytes from peripheral blood and oral mucosal epithelial stem cells (OMESCs) from biopsies of buccal mucosa showed that approximately 80% were homozygous mutant cells and 20% were heterozygous. Cytogenetic and molecular analyses excluded genomic alterations, thus suggesting a de novo mutation followed by an allelic gene conversion of the wild-type allele by de novo mutant allele as a possible mechanism to explain the homozygous condition. R311K-p63 OMESCs were expanded in vitro and heterozygous holoclones selected following clonal analysis. These R311K-p63 OMESCs were able to generate well-organized and stratified epithelia in vitro, resembling the features of healthy tissues. This study supports the rationale for the development of cultured autologous oral mucosal epithelial stem cell sheets obtained by selected heterozygous R311K-p63 stem cells, as an effective and personalized therapy for reconstructing the ocular surface of this unique case of EEC syndrome, thus bypassing gene therapy approaches.

SIGNIFICANCE

This case demonstrates that in a somatic mosaicism context, a novel homozygous mutation in the p63 gene can arise as a consequence of an allelic gene conversion event, subsequent to a de novo mutation. The heterozygous mutant R311K-p63 stem cells can be isolated by means of clonal analysis and given their good regenerative capacity, they may be used to successfully correct the corneal defects present in this unique case of ectrodactyly-ectodermal dysplasia-clefting syndrome.

Ocular surface involvements in ectrodactyly-ectodermal dysplasia-cleft syndrome

PURPOSE

To present the ocular manifestation of 2 cases of ectrodactyly-ectodermal dysplasia-cleft syndrome, a multiple congenital anomaly syndrome caused by a single point mutation of the p63 gene that controls epidermal development and homeostasis and to present treatment options.

CASE REPORTS AND DISCUSSION

Patient 1 presented with mild signs and symptoms of dry eye and limbal stem cell deficiency with retention of 20/30 vision. Patient 2 presented with severe signs and symptoms of limbal stem cell deficiency with diffuse corneal scarring and counting fingers vision. This second patient's course was complicated by allergic conjunctivitis and advanced steroid-induced glaucoma. The cause of visual loss in ectrodactyly-ectodermal dysplasia-cleft syndrome appears to be multifactorial and likely includes inflammation of the ocular surface, tear film abnormalities, eyelid abnormalities, and limbal stem cell deficiency. Treatment modalities including lubrication, contact lenses, and limbal stem cell transplantation are reviewed.

CONCLUSIONS

The ophthalmic conditions seen in ectrodactyly-ectodermal dysplasia-cleft syndrome frequently lead to vision loss. Early correct diagnosis and appropriate therapy are paramount because p63 gene mutations have a critical role in maintaining the integrity of the ocular surface in the setting of limbal stem cell deficiency, especially if there are other ocular surface insults such as lid disease, meibomian gland dysfunction and toxicity from topical medications. Patients should be monitored at regular, frequent intervals; and particular attention should be taken to avoid adverse secondary effects of these conditions and medications.

A novel c.1037C > G (p.Ala346Gly) mutation in TP63 as cause of the ectrodactyly-ectodermal dysplasia and cleft lip/palate (EEC) syndrome

Ectrodactyly – ectodermal dysplasia and cleft lip/palate (EEC) syndrome (OMIM 604292) is a rare disorder determined by mutations in the TP63 gene. Most cases of EEC syndrome are associated to mutations in the DNA binding domain (DBD) region of the p63 protein. Here we report on a three-generation Brazilian family with three individuals (mother, son and grandfather) affected by EEC syndrome, determined by a novel mutation c.1037C > G (p.Ala346Gly). The disorder in this family exhibits a broad spectrum of phenotypes: two individuals were personally examined, one presenting the complete constellation of EEC syndrome manifestations and the other presenting an intermediate phenotype; the third affected, a deceased individual not examined personally and referred to by his daughter, exhibited only the split-hand/foot malformation (SHFM). Our findings contribute to elucidate the complex phenotype-genotype correlations in EEC syndrome and other related TP63-mutation syndromes. The possibility of the mutation c.1037C > G being related both to acro-dermato-ungual-lacrimal-tooth (ADULT) syndrome and SHFM is also raised by the findings here reported.

Contribution of polymorphisms in genes associated with craniofacial development to the risk of nonsyndromic cleft lip and/or palate in the Brazilian population

Background and Objective: Nonsyndromic cleft lip and/or palate (NSCL/P) is a complex disease associated with both genetic and environmental factors. One strategy for identifying of possible NSCL/P genetic causes is to evaluate polymorphic variants in genes involved in the craniofacial development. Design: We carried out a case-control analysis of 13 single nucleotide polymorphisms in 9 genes related to craniofacial development, including TBX1, PVRL1, MID1, RUNX2, TP63, TGF?3, MSX1, MYH9 and JAG2, in 367 patients with NSCL/P and 413 unaffected controls from Brazil to determine their association with NSCL/P. Results: Four out of 13 polymorphisms (rs28649236 and rs4819522 of TBX1, rs7940667 of PVRL1 and rs1057744 of JAG2) were presented in our population. Comparisons of allele and genotype frequencies revealed that the G variant allele and the AG/GG genotypes of TBX1 rs28649236 occurred in a frequency significantly higher in controls than in the NSCL/P group (OR: 0.41; 95% CI: 0.25-0.67; p=0.0002). The frequencies of rs4819522, rs7940667 and rs1057744 minor alleles and genotypes were similar between control and NSCL/P group, without significant differences. No significant associations among cleft types and polymorphisms were observed. Conclusion: The study suggests for the first time evidences to an association of the G allele of TBX1 rs28649236 polymorphism and NSCL/P.

Key words:Cleft lip, cleft palate, polymorphism, genetic.

Dental and Maxillofacial Characteristics of Six Japanese Individuals with Ectrodactyly-Ectodermal Dysplasia-Clefting Syndrome

Objective

Ectrodactyly-ectodermal dysplasia-clefting syndrome is a congenital anomaly characterized by ectodermal dysplasia, ectrodactyly, cleft lip and palate, and lacrimal duct anomalies. Because this syndrome is frequently accompanied by a congenital lack of teeth, narrow palate, and malocclusion, comprehensive orthodontic intervention is required.

Design

To highlight the specific dental and maxillofacial characteristics of ectrodactylyectodermal dysplasia-clefting syndrome, six Japanese individuals diagnosed with the syndrome are described here.

Patients

The subjects consisted of two boys and four girls (age range, 6.0 to 13.9 years) diagnosed with ectrodactyly-ectodermal dysplasia-clefting syndrome by medical and dental specialists. Their conditions included ectodermal dysplasia (hypodontia, microdontia, enamel hypoplasia, and abnormalities in hair and nails), cleft lip and/or palate, and ectrodactyly. Cephalograms, panoramic x-rays, and dental casts were taken; systemic complications were recorded at the first visit to our dental hospital.

Results

All individuals had severe oligodontia with 9 to 18 missing teeth. The missing teeth were mainly maxillary and mandibular incisors and second bicuspids, arranged in a symmetrical manner. Cephalometric analysis showed retruded and short maxilla due to cleft lip and/or palate. It is interesting that all individuals showed a characteristically shaped mandibular symphysis with a retruded point B. It is likely that this unusual symphyseal morphology is due to the lack of mandibular incisors.

Conclusions

This study demonstrates the presence of severe oligodontia in the incisal and premolar regions and describes a characteristic maxillary and mandibular structure in Japanese individuals with ectrodactyly-ectodermal dysplasia-clefting syndrome.

A novel de novo missense mutation in TP63 underlying germline mosaicism in AEC syndrome: implications for recurrence risk and prenatal diagnosis

Ankyloblepharon-ectodermal defects-cleft lip/palate (AEC) syndrome is a rare autosomal dominant ectodermal dysplasia syndrome. It is caused by heterozygous mutations in TP63, encoding a transcriptional factor of the p53 family. Mutations in TP63, mainly missense in exons 13 and 14 encoding the sterile alpha motif (SAM) and the transactivation inhibitory (TI) domains, account for 99% of mutations in individuals with AEC syndrome. Of these, ≥70% are de novo mutations, present in the affected patient, but not in parents nor in healthy siblings. However, when a mutation appears de novo, it is not possible to differentiate between a sporadic mutation, or germline mosaicism in the parents. In this latter case, there is a risk of having additional affected offspring. We describe two sisters with AEC syndrome, whose parents were unaffected. Both patients carried the heterozygous c.1568T>C substitution in exon 13 of TP63, resulting in a p.L523P change in the SAM domain of the protein. Analyses of DNA from parental blood cells, seminal fluid (from the father) and maternal cells (buccal, vaginal, and cervical) did not reveal the mutation, suggesting that the mosaicism may involve a very low percentage of cells (very low grade somatic mosaicism) or, more likely, maternal gonadal mosaicism. Mosaicism must be considered for the assessment of recurrence risk during genetic counseling in AEC syndrome, and pre-implantation/prenatal genetic diagnosis should be offered to all couples, even when the mutation is apparently de novo.

Analysis of large phenotypic variability of EEC and SHFM4 syndromes caused by K193E mutation of the TP63 gene

EEC (ectrodactyly, ectodermal dysplasia, clefting; OMIM 604292) is an autosomal dominant developmental disorder resulting mainly from pathogenic mutations of the DNA-binding domain (DBD) of the TP63 gene. In this study, we showed that K193E mutation in nine affected individuals of a four-generation kindred with a large degree of phenotypic variability causes four different syndromes or TP63-related disorders: EEC, Ectrodactyly-ectodermal dysplasia (EE), isolated ectodermal dysplasia, and isolated Split Hand/Foot Malformation type 4 (SHFM4). Genotype-phenotype and DBD structural modeling analysis showed that the K193-located loop L2-A is associated with R280 through hydrogen bonding interactions, while R280 mutations also often cause large phenotypic variability of EEC and SHFM4. Thus, we speculate that K193 and several other DBD mutation-associated syndromes may share similar pathogenic mechanisms, particularly in the case of the same mutation with different phenotypes. Our study and others also suggest that the phenotypic variability of EEC is attributed, at least partially, to genetic and/or epigenetic modifiers.

Limbal stem cell deficiency and ocular phenotype in ectrodactyly-ectodermal dysplasia-clefting syndrome caused by p63 mutations

OBJECTIVE

To describe the ocular phenotype in patients with ectrodactyly-ectodermal dysplasia-clefting (EEC) syndrome (MIM#604292) and to determine the pathogenic basis of visual morbidity.

DESIGN

Retrospective case series.

PARTICIPANTS

Nineteen families (23 patients) affected by EEC syndrome from the United Kingdom, Ireland, and Italy.

METHODS

General medical examination to fulfill the diagnostic criteria for EEC syndrome and determine the phenotypic severity. Mutational analysis of p63 was performed by polymerase chain reaction-based bidirectional Sanger sequencing. All patients with EEC syndrome underwent a complete ophthalmic examination and ocular surface assessment. Limbal stem cell deficiency (LSCD) was diagnosed clinically on the basis of corneal conjunctivalization and anatomy of the limbal palisades of Vogt. Impression cytology using immunofluorescent antibodies was performed in 1 individual. Histologic and immunohistochemical analyses were performed on a corneal button and corneal pannus from 2 EEC patients.

MAIN OUTCOME MEASURES

The EEC syndrome phenotypic severity (EEC score), best-corrected Snellen visual acuity (decimal fraction), slit-lamp biomicroscopy, tear function index, tear breakup time, LSCD, p63 DNA sequence variants, impression cytology, and corneal histopathology.

RESULTS

Eleven heterozygous missense mutations in the DNA binding domain of p63 were identified in all patients with EEC syndrome. All patients had ocular involvement and the commonest was an anomaly of the meibomian glands and lacrimal drainage system defects. The major cause of visual morbidity was progressive LSCD, which was detected in 61% (14/23). Limbal stem cell deficiency was related to advancing age and caused a progressive keratopathy, resulting in a dense vascularized corneal pannus, and eventually leading to visual impairment. Histologic analysis and impression cytology confirmed LSCD.

CONCLUSIONS

Heterozygous p63 mutations cause the EEC syndrome and result in visual impairment owing to progressive LSCD. 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.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any of the materials discussed in this article.