ADULT ectodermal dysplasia syndrome resulting from the missense mutation R298Q in the p63 gene

Absent meibomian glands and cone dystrophy in ADULT syndrome: identification by whole exome sequencing of pathogenic variants in two causal genes TP63 and CNGB3

BACKGROUND

Ectrodactyly is a rare congenital limb malformation characterized by a deep median cleft of the hand and/or foot due to the absence of central rays. It could be isolated or depicts a part of diverse syndromic forms. Heterozygous pathogenic variants in the TP63 gene are responsible for at least four rare syndromic human disorders associated with ectrodactyly. Among them, ADULT (Acro-Dermato-Ungual-Lacrimal-Tooth) syndrome is characterized by ectodermal dysplasia, excessive freckling, nail dysplasia, and lacrimal duct obstruction, in addition to ectrodactyly and/or syndactyly. Ophthalmic findings are very common in TP63-related disorders, consisting mainly of lacrimal duct hypoplasia. Absent meibomian glands have also been well documented in EEC3 (Ectrodactyly Ectodermal dysplasia Cleft lip/palate) syndrome but not in ADULT syndrome.

METHODS

We report a case of syndromic ectrodactyly consistent with ADULT syndrome, with an additional ophthalmic manifestation of agenesis of meibomian glands. The proband, as well as her elder sister, presented with congenital cone dystrophy.The molecular investigation was performed in the proband using Whole Exome Sequencing. Family segregation of the identified variants was confirmed by Sanger sequencing.

RESULTS

Two clinically relevant variants were found in the proband: the novel de novo heterozygous missense c.931A > G (p.Ser311Gly) in the TP63 gene classified as pathogenic, and the homozygous nonsense pathogenic c.1810C > T (p.Arg604Ter) in the CNGB3 gene. The same homozygous CNGB3 variation was also found in the sister, explaining the cone dystrophy in both cases.

CONCLUSIONS

Whole Exome Sequencing allowed dual molecular diagnoses: de novo TP63-related syndromic ectrodactyly and familial CNGB3-related congenital cone dystrophy.

Case report: ADULT syndrome: a rare case of congenital lacrimal duct abnormality

Acro-dermato-ungual-lacrimal-tooth (ADULT) syndrome is a rare autosomal dominant inherited disease caused due to mutations in the TP63 gene. More commonly, mutations in the TP63 gene result in ectodermal dysplasia and/or orofacial cleft. ADULT syndrome is a type of ectoderm-related tissue dysplasia. This case report describes a patient with chronic tearing, congenital atresia, and obstruction of the lacrimal ducts, which are the main clinical manifestations of ADULT syndrome. This patient also presented with some clinical manifestations that were different from those of ADULT syndrome, namely, mild eyelid fusion and abnormal development of the fifth finger (a stiff fifth finger with camptodactyly that was shortened in length). The gene mutation in this patient was also at a site different from those usually reported in the literature. In this patient, c.518G > T resulted in p. G173V (accession number: NM_003722; exon4). We performed successful dacryocystorhinostomy and artificial lacrimal duct implantation. As shown above, we discussed the clinical characteristics and genetics of the disease in detail. In sharing this case, we aim to contribute to the current understanding of the genes and clinical manifestations of ADULT syndrome and to assist clinicians in the clinical diagnosis of TP63 mutation-related diseases.

ADULT Phenotype and rs16864880 in the TP63 Gene: Two New Cases and Review of the Literature

The TP63 gene has been described in 5 overlapping limb malformation disorders, including a rare autosomal dominant ectodermal disorder named acro-dermato-ungual-lacrimal-tooth (ADULT) syndrome. This article describes 2 patients with ectrodactyly and variable features related to ectodermal dysplasia/ADULT syndrome, and the polymorphism rs16864880 in the TP63 gene, which was not present in their parents. The role of this variant in the genesis of this condition is discussed, based upon a review of 40 cases. The results suggested that rs16864880 may not be directly related to ADULT syndrome. However, it is not possible to exclude its participation in gene interactions in the limb development pathway.

p63 is an alternative p53 repressor in melanoma that confers chemoresistance and a poor prognosis

p63 is up-regulated in melanoma and prevents nuclear accumulation of p53.

The role of apoptosis in melanoma pathogenesis and chemoresistance is poorly characterized. Mutations in TP53 occur infrequently, yet the TP53 apoptotic pathway is often abrogated. This may result from alterations in TP53 family members, including the TP53 homologue TP63. Here we demonstrate that TP63 has an antiapoptotic role in melanoma and is responsible for mediating chemoresistance. Although p63 was not expressed in primary melanocytes, up-regulation of p63 mRNA and protein was observed in melanoma cell lines and clinical samples, providing the first evidence of significant p63 expression in this lineage. Upon genotoxic stress, endogenous p63 isoforms were stabilized in both nuclear and mitochondrial subcellular compartments. Our data provide evidence of a physiological interaction between p63 with p53 whereby translocation of p63 to the mitochondria occurred through a codependent process with p53, whereas accumulation of p53 in the nucleus was prevented by p63. Using RNA interference technology, both isoforms of p63 (TA and ΔNp63) were demonstrated to confer chemoresistance, revealing a novel oncogenic role for p63 in melanoma cells. Furthermore, expression of p63 in both primary and metastatic melanoma clinical samples significantly correlated with melanoma-specific deaths in these patients. Ultimately, these observations provide a possible explanation for abrogation of the p53-mediated apoptotic pathway in melanoma, implicating novel approaches aimed at sensitizing melanoma to therapeutic agents.

ADULT syndrome due to an R243W mutation in TP63

Acro-dermato-ungual-lacrimal-tooth (ADULT) syndrome is a rare, autosomal dominant form of ectodermal dysplasia due to TP63 mutations. ADULT syndrome is much less common than the more classical forms of TP63-associated ectodermal dysplasias, such as ectrodactyly-ectodermal dysplasia-cleft lip/palate (EEC) syndrome and ankyloblepharon-ectodermal defects-cleft lip/palate syndrome. ADULT syndrome is characterized by ectrodactyly, syndactyly, and excessive freckling, in addition to more typical ectodermal defects, including hypodontia, lacrimal duct anomalies, hypotrichosis, and onychodysplasia. Unlike some of the other TP63-associated ectodermal dysplasias, ADULT syndrome lacks clefting and ankyloblepharon. 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.

Cleft palate and ADULT phenotype in a patient with a novel TP63 mutation suggests lumping of EEC/LM/ADULT syndromes into a unique entity: ELA syndrome

Acro-dermato-ungual-lacrimal-tooth (ADULT) syndrome is a rare condition belonging to the group of ectodermal dysplasias caused by TP63 mutations. Its clinical phenotype is similar to ectrodactyly-ectodermal dysplasia-cleft lip/palate (EEC) and limb-mammary syndrome (LMS), and differs from these disorders mainly by the absence of cleft lip and/or palate. We report on a 39-year-old patient who was found to be heterozygous for a c.401G > T (p.Gly134Val) de novo mutation of TP63. This patient had the ADULT phenotype associated with cleft palate. Our findings, rather than extend the clinical spectrum of ADULT syndrome, suggest that cleft palate can no longer be considered an element for differential diagnosis for ADULT, EEC, and LMS. Our data, added to other reports on overlapping phenotypes, support the combining of these three phenotypes into a unique entity that we propose to call "ELA syndrome," which is an acronym of ectrodactyly-ectodermal dysplasia-cleft lip and palate, limb-mammary, and ADULT syndromes.

Dynamic expression of the p53 family members p63 and p73 in the mouse and human telencephalon during development and in adulthood

p63 and p73, family members of the tumor suppressor p53, are critically involved in the life and death of mammalian cells. They display high homology and may act in concert. The p73 gene is relevant for brain development, and p73-deficient mice display important malformations of the telencephalon. In turn, p63 is essential for the development of stratified epithelia and may also play a part in neuronal survival and aging. We show here that p63 and p73 are dynamically expressed in the embryonic and adult mouse and human telencephalon. During embryonic stages, Cajal-Retzius cells derived from the cortical hem co-express p73 and p63. Comparison of the brain phenotypes of p63- and p73- deficient mice shows that only the loss of p73 function leads to the loss of Cajal-Retzius cells, whereas p63 is apparently not essential for brain development and Cajal-Retzius cell formation. In postnatal mice, p53, p63, and p73 are present in cells of the subventricular zone (SVZ) of the lateral ventricle, a site of continued neurogenesis. The neurogenetic niche is reduced in size in p73-deficient mice, and the numbers of young neurons near the ventricular wall, marked with doublecortin, Tbr1 and calretinin, are dramatically decreased, suggesting that p73 is important for SVZ proliferation. In contrast to their restricted expression during brain development, p73 and p63 are widely detected in pyramidal neurons of the adult human cortex and hippocampus at protein and mRNA levels, pointing to a role of both genes in neuronal maintenance in adulthood.

TP63 gene mutations in Chinese P63 syndrome patients

TP63 plays an essential role in the development of epidermis and skin appendages. Mutations in TP63 can give rise to a series of syndromes characterized by various combinations of ectodermal dysplasia, limb malformations, and orofacial clefting in many populations. To test whether TP63 is the disease-causative gene for these phenotypes in Chinese, we recruited two Chinese Ectrodactyly-Ectodermal-dysplasia-Cleft lip/palate syndrome (EEC) cases and a Limb-Mammary-Syndrome (LMS) patient to carry out TP63 gene sequencing. Three missense mutation, c.812G>C (Ser271Thr), c.611G>A (Arg204Gln), and c.680G>A (Arg227Gln), which lead to the substitution of highly conserved amino acids in the DNA-binding domain of TP63, were identified. These mutations were predicted to disrupt DNA-binding specificity and affinity. To our knowledge, this is the first report of EEC and LMS syndromes in individuals of Chinese descent. Analysis of our data demonstrated that TP63 is critical for the development of ectoderm in humans.

Ectrodactyly-ectodermal dysplasia-clefting syndrome associated with p63 mutation and an uncommon phenotype

Ectrodactyly-ectodermal dysplasia-clefting syndrome is an uncommon disorder that includes a clinical spectrum of limb, facial, ocular, internal ear, and urogenital malformations. The disease is caused by heterozygous mutations in the 3q27-29 located p63 gene. 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. Scattered freckles on face, legs, and abdominal region, an uncommon feature associated with this syndrome, were recognized in our patient. The clinical features and genotype-phenotype correlation with previous p63 mutations related to the syndrome are discussed and compared with those observed in our patient. This case expands the phenotypic spectrum of ectrodactyly-ectodermal dysplasia-clefting syndrome.

Management of dry eye related to systemic diseases in childhood and longterm follow-up

PURPOSE

Dry eye in children is not common in general practice and is usually referred to tertiary centres for diagnostic confirmation. In the present review we examine the potential causes of dry eye in children and report the management and longterm follow-up of dry eye in childhood with reference to clinical diversity, systemic associations, ocular outcomes and treatment trends.

METHODS

A retrospective, consecutive case series was studied by evaluating the clinical charts of children with dry eye over a 96-month period. Minimal diagnostic inclusion criteria were presence of ocular surface damage and tear deficiency.

RESULTS

Fourteen patients with an age range at presentation of 1-17 years were evaluated. Ten patients were female, four were male and all had bilateral involvement. The most frequent symptoms were red eye, photophobia and low visual acuity (VA). Four patients had corneal ulcers. Two patients had best corrected visual acuity (BCVA) < or = 20/200 at first examination. One of these plus another patient presented with BCVA < or = 20/200 at the last visit. All patients were treated with artificial tears; three received autologous serum tears and five submitted to conjunctival flaps to preserve the integrity of the eye. Associated systemic conditions were found in all patients and were congenital in six of them.

CONCLUSIONS

Early manifestations of dry eye in childhood are a potential indication of systemic disease. The ocular condition may be misdiagnosed and correct treatment delayed. Most diseases are bilateral and may jeopardize VA. Systemic investigation, close follow-up and preparing the family for longterm and multidisciplinary treatment are necessary to preserve ocular health and identify systemic associations.

Pattern of p63 mutations and their phenotypes--update

Heterozygous mutations in the transcription factor gene p63 cause at least six different syndromes with various combinations of ectodermal dysplasia, orofacial clefting and limb malformations. Here we will present an update of mutations in the p63 gene together with a comprehensive overview of the associated clinical features in 227 patients. These data confirm the previously recognized genotype-phenotype associations. Moreover, we report that there is a large degree of clinical variability in each of the p63-associated disorders. This is illustrated by the different phenotypes that are seen for the five-hotspot mutations that explain almost 90% of all EEC syndrome patients.

Acro-dermato-ungual-lacrimal-tooth-like syndrome: report of a family with variable expression

We report the case of a young boy with fine hair, mild nail dysplasia, blocked nasolacrimal ducts, absence of central incisors, bilateral oligodactyly of feet and anal stenosis. His father showed the same spectrum of anomalies with mild expression. He had mild nail dysplasia, blocked nasolacrimal ducts, inferior dental cysts with consequent premature tooth loss, frequent dental decays consequent to enamel abnormality and cutaneous syndactyly of the second and third right toe. The acro-dermato-ungual-lacrimal-tooth syndrome was suspected and molecular analysis of the P63 gene was performed, but no mutation was found. Although P63 gene analysis was negative, we think that both cases show clinical overlap with the acro-dermato-ungual-lacrimal-tooth syndrome and confirm the wide expression of this condition, even in the same family.

Delineation of the ADULT syndrome phenotype due to arginine 298 mutations of the p63 gene

The ADULT syndrome (Acro-Dermato-Ungual-Lacrimal-Tooth, OMIM 103285) is a rare ectodermal dysplasia associated with limb malformations and caused by heterozygous mutations in p63. ADULT syndrome has clinical overlap with other p63 mutation syndromes, such as EEC (OMIM 604292), LMS (OMIM 603543), AEC (106260), RHS (129400) and SHFM4 (605289). ADULT syndrome characteristics are ectrodactyly, ectodermal dysplasia, mammary gland hypoplasia and normal lip and palate. The latter findings allow differentiation from EEC syndrome. LMS differs by milder ectodermal involvement. Here, we report three new unrelated ADULT syndrome families, all with mutations of arginine 298. On basis of 16 patients in five families with R298 mutation, we delineate the ADULT syndrome phenotype. In addition, we have documented a gain-of-function effect on the dNp63gamma isoform caused by this mutation. We discuss the possible relevance of oral squamous cell carcinoma in one patient, who carries this p63 germline mutation.

Further phenotypic and genetic variation in ADULT syndrome

ADULT (Acro-dermato-ungual-lacrimal-tooth) syndrome is characterized by ectrodactyly, syndactyly, fingernail and toenail dysplasia, hypoplasia of the breast and nipple, excessive freckling, lacrimal duct atresia, frontal alopecia, primary hypodontia, and/or early loss of permanent teeth. It is a rare autosomal dominant disorder which has been linked to mutation in the p63 gene. The p63 gene has been described in five overlapping limb malformation syndromes including the EEC syndrome (ectodermal ectrodactyly clefting). We report on the first case of ADULT syndrome of a mother and daughter with a new mutation R227Q in exon 6 of the p63 gene. This has not been previously associated with ADULT syndrome but only seen in EEC. In addition to the previously reported features of ADULT syndrome this report also describes some additional findings including hyperextensibility at the distal interphalageal joints, bilateral thumb duplication, bifid toenails, symptoms of urinary retention, vesicoureteric reflux, prominent ears, conductive hearing loss, and an overgrowth of a patch of hair in the midline of the neck. 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.

Acro-dermato-ungual-lacrimal-tooth (ADULT) syndrome: Report of a child with phenotypic overlap with ulnar-mammary syndrome and a new mutation inTP63

We report on a new patient with clinical findings consistent with acro-dermato-ungual-lacrimal-tooth (ADULT) syndrome. The child had sparse hair, extensive freckling, lacrimal duct stenosis, oligodontia, dystrophic nails, reduced sweating, and bilateral athelia. Examination of his hands showed ulnar ray hypoplasia with bilateral fifth finger brachydactyly and camptodactyly. He also had surgical repair of an imperforate anus. Mutation analysis of TP63 showed a single nucleotide substitution, c.G518A, predicting a novel missense mutation, p.V114M in exon 4. This is the third mutation to be reported in TP63 in ADULT syndrome.