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

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.

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.

Neurocristopathies: New insights 150 years after the neural crest discovery

The neural crest (NC) is a transient, multipotent and migratory cell population that generates an astonishingly diverse array of cell types during vertebrate development. These cells, which originate from the ectoderm in a region lateral to the neural plate in the neural fold, give rise to neurons, glia, melanocytes, chondrocytes, smooth muscle cells, odontoblasts and neuroendocrine cells, among others. Neurocristopathies (NCP) are a class of pathologies occurring in vertebrates, especially in humans that result from the abnormal specification, migration, differentiation or death of neural crest cells during embryonic development. Various pigment, skin, thyroid and hearing disorders, craniofacial and heart abnormalities, malfunctions of the digestive tract and tumors can also be considered as neurocristopathies. In this review we revisit the current classification and propose a new way to classify NCP based on the embryonic origin of the affected tissues, on recent findings regarding the molecular mechanisms that drive NC formation, and on the increased complexity of current molecular embryology techniques.

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.

Novel TBX3 mutation in a family of Cypriot ancestry with ulnar-mammary syndrome

Ulnar-mammary syndrome (UMS) is an autosomal dominant disorder resulting from TBX3 haploinsufficiency. It typically affects limb, apocrine gland, hair, tooth and genital development and shows marked intrafamilial and interfamilial variability in phenotypic expression. We report a family (twin brothers and their father) affected with UMS because of a novel TBX3 mutation. The twin brothers showed classical features of UMS, whereas their father was mildly affected. The c.1423C>T (p.Q475*) nonsense mutation in exon 6 of the TBX3 gene identified in the patients by targeted Sanger sequencing is predicted to lead to premature termination of translation. This is the first report of a Cypriot family with UMS resulting from a novel TBX3 mutation. This report provides additional evidence in support of the rich variability in phenotypic expression, the mutational heterogeneity and ethnic diversity associated with this rare condition.

EEC- and ADULT-associated TP63 mutations exhibit functional heterogeneity toward P63 responsive sequences

TP63 germ-line mutations are responsible for a group of human ectodermal dysplasia syndromes, underlining the key role of P63 in the development of ectoderm-derived tissues. Here, we report the identification of two TP63 alleles, G134V (p.Gly173Val) and insR155 (p.Thr193_Tyr194insArg), associated to ADULT and EEC syndromes, respectively. These alleles, along with previously identified G134D (p.Gly173Asp) and R204W (p.Arg243Trp), were functionally characterized in yeast, studied in a mammalian cell line and modeled based on the crystal structure of the P63 DNA-binding domain. Although the p.Arg243Trp mutant showed both complete loss of transactivation function and ability to interfere over wild-type P63, the impact of p.Gly173Asp, p.Gly173Val, and p.Thr193_Tyr194insArg varied depending on the response element (RE) tested. Interestingly, p.Gly173Asp and p.Gly173Val mutants were characterized by a severe defect in transactivation along with interfering ability on two DN-P63α-specific REs derived from genes closely related to the clinical manifestations of the TP63-associated syndromes, namely PERP and COL18A1. The modeling of the mutations supported the distinct functional effect of each mutant. The present results highlight the importance of integrating different functional endpoints that take in account the features of P63 proteins' target sequences to examine the impact of TP63 mutations and the associated clinical variability.

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.

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.

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.