PRKD1-related Telangiectasia-ectodermal dysplasia-brachydactyly-cardiac anomaly syndrome: case report and review of the literature

Telangiectasia-ectodermal dysplasia-brachydactyly-cardiac anomaly (TEBC) syndrome is a rare autosomal dominant condition, recently linked to the protein kinase D1 (PRKD1) gene. The phenotype of TEBC remains incomplete at this point. Our aim is to improve the characterization of the clinical and molecular aspects of the TEBC syndrome. We report on the 8th patient carrying a heterozygous de novo variation of PRKD1 c.2134G>A, p.(Val712Met) identified by trio exome sequencing. The proband presents with partial atrioventricular septal defect, brachydactyly, ectodermal dysplasia, telangiectasia that developed in childhood, intellectual disability with microcephaly, multicystic renal dysplasia and moderate hormonal resistance. In view of this 8th description and review of the literature, it appears that neurodevelopmental disorders and microcephaly are frequently associated with PRKD1 missense variants, adding to the four main clinical signs described initially in the TEBC syndrome. Further descriptions are required to confirm the observed endocrine and kidney abnormalities. This should contribute to a more comprehensive understanding of the phenotypic spectrum and may help establish genotype-phenotype correlations. In the context of genotype-first strategy, accurate patient descriptions are fundamental. Characterization of specific syndromic associations is essential for variant interpretation support and patient follow-up, even in very rare diseases, such as the TEBC syndrome.

Three-Dimensional Modeling and Quantitative Assessment of Mandibular Volume in Ectodermal Dysplasia: A Case Series

Background and Objectives: Ectodermal dysplasia (ED)-a genetic disorder-is characterized by severe tooth deficiency. We compared the mandibular volume and the sagittal and horizontal mandibular widths between patients with ED (ED group) and individuals without tooth deficiency (control group) using three-dimensional modeling. We hypothesized that the mandibular volume differs in ED cases owing to congenital tooth deficiency. Materials and Methods: We used previously obtained cone-beam computed tomography (CBCT) images of 13 patients with ED. The control group data comprised retrospective CBCT images of patients of similar age and sex with a skeletal relationship of class 1. Further, using the three-dimensional image analysis software, the tooth crowns were separated from the mandible, the mandible was reconstructed and the gonion-to-gonion distance in the mandible was marked, the distance to the menton point was measured, and the distance between the two condyles was measured and compared with the control group. Results: Overall, 46.2% and 53.8% of the participants were men and women, respectively. In the ED group, the mean age of the participants was 15.46 (range, 6-24) years, and the mean number of mandibular teeth was 4.62. Notably, the edentulous mandible volume of the ED group (27.020 mm3) was statistically significantly smaller than that of the control group (49.213 mm3) (p < 0.001). There was no difference between the two groups in terms of the marked points. For data analysis, the Shapiro-Wilk test, independent samples t-test, and Mann-Whitney U test were used. Conclusions: It has been considered that mandible volume does not develop in ED cases because of missing teeth. Modern practices, such as the CBCT technique and three-dimensional software, may be effective in identifying the true morphologic features, especially in patients with genetic syndromes affecting the maxillofacial structure.

Tooth agenesis related to a novel KDF1 variant: A case report and literature review

OBJECTIVES

To investigate the role of Keratinocyte Differentiation Factor 1 (KDF1) in ectodermal dysplasia (ED) and nonsyndromic tooth agenesis (NSTA) and perform a literature review.

METHODS

Genome sequencing was used to identify genetic variants in a Thai, NSTA proband and validated through Sanger sequencing. Pathogenicity was assessed using ACMG guidelines, MetaRNN and AlphaMissense. A comprehensive review of KDF1/NSTA cases informed genotype-phenotype analysis of the proband.

RESULTS

The proband revealed multiple missing teeth, caries and extensive periodontal disease. Deep phenotyping showed no signs of ED beyond tooth agenesis. The identified novel KDF1 variant, p.Ile243Leu, was classified as 'likely pathogenic' by ACMG and predicted as 'detrimental' by MetaRNN and AlphaMissense analyses. A total of 14 reviewed KDF1 cases revealed ED-associated variants (3 variants in 8 patients) clustering in the region of amino acids 251-275, within the DUF4656 domain, while NSTA-causing variants (4 variants in 6 patients) were typically found in amino- or carboxy-termini to this region. KDF1/NSTA cases exhibited an average of 15 missing teeth, with a higher prevalence in the mandible.

CONCLUSION

This study identifies a novel KDF1 variant-related NSTA in Thai people. The genotype-phenotype correlates suggest a distinctive pattern and tooth agenesis of KDF1-related NSTA.

Ocular phenotype and therapeutic interventions in keratitis-ichthyosis-deafness (KID) syndrome

BACKGROUND

To report ocular manifestations, clinical course, and therapeutic management of patients with molecular genetically confirmed keratitis-ichthyosis-deafness syndrome.

METHODS

Four patients, aged 19 to 46, with keratitis-ichthyosis-deafness syndrome from across the UK were recruited for a general and ocular examination and GJB2 (Cx26) mutational analysis. The ocular examination included best-corrected visual acuity, slit-lamp bio-microscopy, and ocular surface assessment. Mutational analysis of the coding region of GJB2 (Cx26) was performed by bidirectional Sanger sequencing.

RESULTS

All four individuals had the characteristic systemic features of keratitis-ichthyosis-deafness syndrome. Each patient was found to have a missense mutation, resulting in the substitution of aspartic acid with asparagine at codon 50 (p.D50N). Main ophthalmic features were vascularizing keratopathy, ocular surface disease, hyperkeratotic lid lesions, recurrent epithelial defects, and corneal stromal scarring. One patient had multiple surgical procedures, including superficial keratectomies and lamellar keratoplasty, which failed to prevent severe visual loss. In contrast, oral therapy with ketoconazole stabilized the corneal and skin disease in two other patients with keratitis-ichthyosis-deafness syndrome. The patient who underwent intracorneal bevacizumab injection showed a marked reduction in corneal vascularization following a single application.

CONCLUSIONS

Keratitis-ichthyosis-deafness syndrome is a rare ectodermal dysplasia caused by heterozygous mutations in GJB2 (Cx26) with a severe, progressive vascularizing keratopathy. Oral ketoconazole therapy may offer benefit in stabilizing the corneal and skin disease.

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.

Intubation in a Case of Ectodermal Dysplasia During Surgery: A Case Report

Ectodermal dysplasia, a heterogeneous group of rare genetic disorders, is characterized by the aberrant development of ectodermal structures, leading to various clinical anomalies. This case report presents a unique and challenging case of a 33-year-old male with ectodermal dysplasia who underwent Le Fort III advancement and implant rehabilitation surgery to address severe craniofacial and dental deficiencies. This case, characterized by facial dysmorphism, craniofacial anomalies, and the absence of a nasal bone, highlights the complexity of surgical planning required to address these diverse clinical features. The crucial element of this report is the innovative approach to airway management through trans mylohyoid/submental intubation, which successfully navigated the patient's aberrant anatomy. Multidisciplinary collaboration played a pivotal role in achieving a holistic and patient-centered approach. By sharing this case, we aim to provide insights into the nuances of managing complex patients with ectodermal dysplasia, emphasizing the importance of individualized care, innovative techniques, and interdisciplinary teamwork to optimize patient outcomes and contribute to advancing medical knowledge.

Dominant frontonasal dysplasia with ectodermal defects results from increased activity of ALX4

Frontonasal dysplasia (FND) refers to a group of rare developmental disorders characterized by abnormal morphology of the craniofacial region. We studied a family manifesting with clinical features typical for FND2 including neurobehavioral abnormalities, hypotrichosis, hypodontia, and facial dysmorphism. Whole-exome sequencing analysis identified a novel heterozygous frameshift insertion in ALX4 (c.985_986insGTGC, p.Pro329Argfs*115), encoding aristaless homeobox 4. This and a previously reported dominant FND2-causing variant are predicted to result in the formation of a similar abnormally elongated protein tail domain. Using a reporter assay, we showed that the elongated ALX4 displays increased activity. ALX4 negatively regulates the Wnt/β-catenin pathway and accordingly, patient keratinocytes showed altered expression of genes associated with the WNT/β-catenin pathway, which in turn may underlie ectodermal manifestations in FND2. In conclusion, dominant FND2 with ectodermal dysplasia results from frameshift variants in ALX4 exerting a gain-of-function effect.

Rehabilitation with implant-supported overdentures in preteens patients with ectodermal dysplasia: A cohort study

INTRODUCTION

Hypohidrotic ectodermal dysplasia (HED) patients suffering of oligo-anodontia require early dental treatment to improve oral functions and reduce social impairment. The aim of this study was to evaluate the skeletal growth, implant and prosthetic survival rate, success, and complications after the rehabilitation with a maxillary denture and an implant-supported overdenture provided by a sliding bar in case of severe hypodontia/anodontia related to HED.

MATERIALS AND METHODS

This retrospective cohort study began in 2009. Nine patients over 7 years old with HED and associated oligo-anodontia who presented at the University of Bologna for dental treatment were included in the study. They were first treated with conventional dentures and then with a maxillary denture and an implant-supported overdenture with a sliding bar connected to two implants placed in the anterior mandible. The subjects treated were followed for 3-12 years. In each case, orthopanoramic and lateral cephalometric radiographic exam were taken before implant placement and annually after prosthetic load. Vertical and transverse dimensions of the mandible in the symphysis area at implant sites were taken on the lateral cephalometric radiography at the time of implant placement and after 5 years from the prosthetic loading to assess the presence or absence of an anterior mandibular growth. Biologic and mechanical complications were also recorded at every visit.

RESULTS

A mandibular vertical growth under the implant apex, at the implant neck, and a sagittal growth of the symphysis after 5 years from the prosthetic loading were observed and measured. Implant and prosthetic success and survival rates were 100% after 8.1 years (mean) follow-up period. No complications were reported except in one patient, where the repositioning of a retentive cap on the counter bar in the superstructure was necessary after 3 years from the prosthetic loading.

CONCLUSIONS

The present study suggests that the growth of the mandible near implant sites continues even after their positioning. Implants can be successfully placed and provide support for prosthetic rehabilitation in preteens patients with HED.

[Ectrodactyly-ectodermal dysplasia-clefting (EEC) syndrome]

The ectrodactyly-ectodermal dysplasia-clefting syndrome is an extremely rare genetic disorder that is inherited as an autosomal dominant trait, but can also occur sporadically. It is characterized by the triad of ectrodactyly (absence of fingers), ectodermal dysplasia and cleft lip and palate along with variable involvement of other organs. Both the ectodermal and mesodermal tissues may be affected resulting in a spectrum of phenotypes. Early diagnosis and treatment signify a unique challenge for those involved in the clinical management, while enable counseling and preparation of parents for the tasks ahead of them. In our report, we describe the case of a patient with sporadic EEC syndrome. In addition to the presentation of the complex phenotype along with the medical interventions, we summarize the most important characteristics of the disease, the diagnostic and therapeutic possibilities as well as the clinical significance of the accurate genetic verification. Using whole exome sequencing, we identified in the 3q28 chromosomal region a pathogenic mutation within the TP63 gene previously linked to the EEC3 phenotypes. The knowledge of pathogenic mutation provides the means to prenatal diagnostics or in vitro fertilization methods that allows us to minimize the possibility of inheriting the syndrome in the patient's offspring. By presenting our case, we aim to draw attention to this rare and disabling disease that requires the high quality works of a multidisciplinary team capable of ensuring good quality of life for the patient. Orv Hetil. 2023; 164(46): 1831-1837.

A new variant of the ectodysplasin A receptor death domain gene associated with anhidrotic ectodermal dysplasia in a Turkish family and its simple diagnosis by restriction fragment length polymorphism

Ectodermal dysplasia (ED), which exhibits a wide range of clinical symptoms, may be classified into three major types: hypohidrotic, anhidrotic, and hidrotic. A male child (proband) showing anhidrotic dysplasia was used as the subject of this study. The biopsy of the big toe revealed that the male child had no sweat glands. Genetic analysis of the patient revealed a mutation caused by a homozygous nucleotide substitution in the EDAR-associated death domain (EDARADD) (rs114632254) gene c.439G>A (p.Gly147Arg). Phenotypically, his teeth were sharp, but eight teeth were missing (oligodontia). The patient had normal nails with dry skin, sparse hair, everted lower lip vermilion, hyperpigmented eyelids, and abnormal nasal bridge morphology around the eyes. There is also a homozygous dominant (healthy) female and a heterozygous male in this family, who are cousins (aunt children) to the heterozygous parents. The daughter of the patient was also heterozygous. This mutation represents homozygous recessive inheritance, which we describe for the first time. Furthermore, we demonstrated that this genetic disorder can be readily diagnosed using the restriction fragment length polymorphism (RFLP) method after digestion with MnII restriction endonuclease.

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.

Hypohidrotic Ectodermal Dysplasia: A Case Report

Ectodermal dysplasia (ED) is a rare genetic disorder that affects the developmental disturbance of ectoderm-derived tissues, organs, and accessory appendages, i.e. skin, hair, tooth, nail, and sweat glands. ED has two types hypohidrotic or anhidrotic ectodermal dysplasia and hidrotic ectodermal dysplasia. We report this case of classical hypohidrotic ectodermal dysplasia (HED) with clubbing. The association of clubbing with HED is still rare. This case report aims to discuss the etiology, clinical manifestations, and management of ectodermal dysplasia. A multidisciplinary approach is required including dentists, nutritionists, dermatologists, and physicians to manage ectodermal dysplasia.

Molecular basis and genetics of hypohidrotic ectodermal dysplasias

Ectodermal dysplasia (ED) is a heterogeneous group of hereditary diseases of the skin and its appendages, which are characterized by impaired development and/or homeostasis of two or more ectoderm derivatives, including: hair, teeth, nails, sweat glands and their modifications (mammary glands, for instance). The overall prevalence of ectodermal dysplasia remains precisely unknown not only in Russia, but also in the world, nor is known the contribution of individual genes to its structure. This complicates the DNA diagnosis establishment of this disease due to the lack of an accurate diagnostic algorithm and a universal cost-effective method of analysis. To date, the most highly-researched genes involved in the development of anhydrous or hypohidrotic forms of ED are EDA, EDAR, EDARADD and WNT10A. The ectodysplasin A (EDA) gene is the cause of the most common X-linked form of ED, a gene from the Wnt family (WNT10A) is responsible for the autosomal recessive form of the disease, and two other genes (EDAR and EDARADD) can cause both autosomal recessive and autosomal dominant forms. This review provides the characteristics of the genes involved in ED, their mutation spectra, the level of their expression in human tissues, as well as the interrelation of the aforementioned genes. The domain structures of the corresponding proteins are considered, as well as the molecular genetic pathways in which they are involved. Animal models for studying this disorder are also taken into consideration. Due to the cross-species genes conservation, their mutations cause the disruption of the development of ectoderm derivatives not only in humans, but also in mice, cows, dogs, and even fish. It can be exploited for a better understanding of the etiopathogenesis of ectodermal dysplasias. Moreover, this article brings up the possibility of recurrent mutations in the EDA and WNT10A genes. The review also presents data on promising approaches for intrauterine ED treatment.

Effects of TP63 mutations on keratinocyte adhesion and migration

The goal of this study was to investigate the molecular mechanisms responsible for the formation of skin erosions in patients affected by Ankyloblepharon-ectodermal defects-cleft lip/palate syndrome (AEC). This ectodermal dysplasia is caused by mutations in the TP63 gene, which encodes several transcription factors that control epidermal development and homeostasis. We generated induced pluripotent stem cells (iPSC) from AEC patients and corrected the TP63 mutations using genome editing tools. Three pairs of the resulting conisogenic iPSC lines were differentiated into keratinocytes (iPSC-K). We identified a significant downregulation of key components of hemidesmosomes and focal adhesions in AEC iPSC-K compared to their gene-corrected counterparts. Further, we demonstrated reduced AEC iPSC-K migration, suggesting the possibility that a process critical for cutaneous wound healing might be impaired in AEC patients. Next, we generated chimeric mice expressing a TP63-AEC transgene and confirmed a downregulation of these genes in transgene-expressing cells in vivo. Finally, we also observed these abnormalities in AEC patient skin. Our findings suggest that integrin defects in AEC patients might weaken the adhesion of keratinocytes to the basement membrane. We propose that reduced expression of extracellular matrix adhesion receptors, potentially in conjunction with previously identified desmosomal protein defects, contribute to skin erosions in AEC.

Prosthodontic Management of a Patient with Ectodermal Dysplasia: Case Report

Ectodermal dysplasia (ED) is an inherited disorder that affects the ectoderm of a developing embryo and impacts structures that originate from it. It typically presents as a triad of missing teeth (anodontia/hypodontia), sparse hair (atrichosis/hypotrichosis), and lack of sweat glands (hypohidrosis), often accompanied by nail dystrophy and palmoplantar hyperkeratosis. There are two main types of this condition: X-linked anhidrotic or hypohidrotic and hidrotic (autosomal type). The oral manifestation of ED may include anodontia or hypodontia, with or without cleft lip and palate. Tooth loss leads to a decrease in the height of the alveolar ridges, resulting in a reduction of the vertical dimension of the lower face, disappearance of the vermilion border, and prominent lips. As a result, the affected person's face may resemble that of an elderly individual. The current case report aims to illustrate the prosthodontic rehabilitation of 16-year-old male patient with ectodermal dysplasia and complete anodontia, visiting Dentistry Teaching Hospital, Kabul, Afghanistan. Fortunately, this patient was acceptably managed with the collaboration of several disciplines.

Molecular Basis of Hereditary Hair Diseases

The hair follicle is an appendage of the skin that undergoes hair cycles throughout life. Recently, numerous genes expressed in the hair follicles have been identified, and variants in some of these genes are now known to underlie hereditary hair diseases in humans. Hereditary hair diseases are classified into non-syndromic and syndromic forms. In the Japanese population, the non-syndromic form of autosomal recessive woolly hair, which is caused by founder pathogenic variants in the lipase H (LIPH) gene, is the most prevalent hereditary hair disease. In addition, other types of hereditary hair diseases are known in Japan, such as Marie-Unna hereditary hypotrichosis, hypohidrotic ectodermal dysplasia, and tricho-rhino-phalangeal syndrome. To ensure correct diagnoses and appropriate patient care, dermatologists must understand the characteristics of each hair disorder. Elucidation of the molecular basis of hereditary hair diseases can directly tell us which genes are crucial for morphogenesis and development of hair follicles in humans. Therefore, continuation of "wet laboratory" research for these diseases remains important. To date, several syndromic forms of hereditary hair diseases have been approved as designated intractable diseases in Japan. As part of our efforts in the Project for Research on Intractable Diseases through the Ministry of Health, Labour, and Welfare of Japan, we anticipate that more hereditary hair diseases be recognized as designated intractable diseases in the future, which will be to the benefit of the affected individuals.

Molecular Modeling Analysis Provides Genotype-Phenotype Correlation Insights in a Patient with Ankyloblepharon-Ectodermal Dysplasia-Clefting Syndrome

Ankyloblepharon-ectodermal defects-cleft lip/palate (AEC) syndrome is a rare autosomal dominant disorder. AEC is caused by mutations in the TP63 gene that encodes the tumor suppressor p63 protein, itself involved in the regulation of epidermal proliferation, development, and differentiation. We present here a typical AEC case of a four-year-old girl with extensive skin erosions and erythroderma of the scalp and the trunk, and to a lesser extent of the limbs, nail dystrophy on the fingers and toes, xerophthalmia, a high-arched palate, oligodontia, and hypohidrosis. Mutation analysis of the TP63 gene detected a de novo missense mutation in exon 14 (c.1799G>T; p.Gly600Val). We discuss the phenotype-genotype correlation by presenting the clinical features of AEC in the patient, and the effect of the detected mutation in p63 structure and function using protein structural modeling, in view of similar cases in the literature. We performed a molecular modeling study in order to link the effect on the protein structure level of the missense mutation G600V. We noted that the introduction of the bulkier Valine residue in place of the slim Glycine residue caused a significantly altered 3D conformational arrangement of that protein region, pushing away the adjacent antiparallel α helix. We propose that the introduced locally altered structure of the G600V mutant p63 has a significant functional effect on specific protein-protein interactions, thus affecting the clinical phenotype.

X-Linked Hypohidrotic Ectodermal Dysplasia (XLHED): A Case Report and Overview of the Diagnosis and Multidisciplinary Modality Treatments

Hypohidrotic ectodermal dysplasia (HED) is a rare genetic disorder caused by a mutation in either the ectodysplasin (EDA), ectodysplasin A receptor (EDAR), EDAR associated via death domain (EDARADD), or Wnt family member 10A (WNT10A) genes that result in impaired development of ectodermal-derived structures. The literature defines two types of ectodermal dysplasia, which are hypohidrotic and hidrotic. X-linked hypohidrotic ectodermal dysplasia (XLHED), also known as Christ-Siemens-Touraine syndrome, is the most common form and is a variant of ectodermal dysplasia characterized by a classical triad of hypo/adontia, hypohidrosis, and hypotrichosis; whereas, hidrotic type of ectodermal dysplasia, also known as Clouston syndrome, is characterized by a triad of onychodysplasia, hypotrichosis, and palmoplantar hyperkeratosis while sparing the sweat glands. Symptoms of XLHED can begin early in life between the ages of one month to 23 months. XLHED is more commonly seen in males due to the x-linked characteristics of the gene mutations. This disease can be diagnosed by physical exam alone, or in combination with molecular genetic testing. XLHED specifically has an estimated occurrence of one in every 20,000 newborns worldwide. Approximately 5,000 people in the United States have the disease.  In this case report, we present an adult patient diagnosed with XLHED. Our objective is to emphasize the significance of early diagnosis, advocate for a multidisciplinary management approach, and shed light on the potential of recombinant protein and targeted gene therapy for further research. By raising awareness of this condition, we aim to improve patient outcomes not only in newborns but also in adults who have already been diagnosed with XLHED.

Case report: A case of incontinentia pigmenti

Incontinentia pigmenti (IP) is a rare neuroectodermal dysplasia caused by mutations in the IKBKG gene. We present a case of a 4-month-old female infant with erythematous vesicular skin lesions on the trunk and extremities. Histopathologic examination of the blisters revealed an eosinophilic infiltrate. Further investigation revealed that her mother had three unexplained miscarriages and two normal uncomplicated pregnancies, resulting in the birth of two male infants. We performed a comprehensive genetic evaluation to rule out the interference of pseudogene IKBKGP, and the infant was finally diagnosed with IP. During the subsequent 2-year follow-up, we observed a significant improvement in her dermatologic symptoms, with no evidence of recurrence, and there were no other associated symptoms in the hair, nails, oral mucosa, eyes, or central nervous system.

A Causal Treatment for X-Linked Hypohidrotic Ectodermal Dysplasia: Long-Term Results of Short-Term Perinatal Ectodysplasin A1 Replacement

X-linked hypohidrotic ectodermal dysplasia (XLHED), caused by a genetic deficiency of ectodysplasin A1 (EDA1), is a rare developmental disorder of ectodermal derivatives such as hair, sweat glands, and teeth. The absence of sweat glands and perspiration can evoke life-threatening hyperthermia. As molecular genetic findings are not always conclusive, the concentrations of circulating EDA1 may help to distinguish between total and partial EDA1 deficiencies. We previously treated nine male patients with obvious signs of XLHED with a recombinant EDA1 replacement protein, Fc-EDA, either shortly after birth (n = 3) or by prenatal administration in gestational week 26 and beyond (n = 6). Here, we present the long-term follow-up for up to six years. In patients who had received Fc-EDA after birth, neither sweat glands nor sweating ability were detected at the age of 12-60 months. In contrast, prenatal EDA1 replacement resulted in ample sweat gland development and pilocarpine-inducible sweating in all treated subjects, who also attained more permanent teeth than their untreated affected relatives. Normal perspiration has persisted for six years in the two oldest boys treated repeatedly with Fc-EDA in utero. When they had a sauna, adequate thermoregulation was evidenced. Lower sweat production after single prenatal dosing may indicate a dose-response relationship. The absence of circulating EDA1 in five prenatally treated subjects proved that these children would have been unable to perspire if they had been left untreated. The sixth infant was shown to produce an EDA1 molecule that, albeit interacting with its cognate receptor, cannot activate EDA1 signaling. In conclusion, a causal treatment of XLHED before birth is feasible.

Assessment of craniofacial growth in individuals with ectodermal dysplasia after complete denture rehabilitation: A preliminary study

Aim

The main purpose was to evaluate the effect of complete denture rehabilitation on the jaw growth pattern in individuals with ectodermal dysplasia from an early age to maturity.

Settings and Design

This was a prospective in vivo study performed in the Department of Prosthodontics, King George Medical University, Lucknow, India.

Materials and Methods

Rehabilitation with three sets of conventional complete dentures was completed in an ectodermal dysplasia case at the age of 5, 10, and 17 years. Cephalometric and diagnostic cast analyses were the methods performed to evaluate jaw growth patterns. Linear and angular measurements obtained after denture rehabilitation were averaged and compared with mean standard values of nearly corresponding ages, as given by Sakamoto and Bolton. Conversely, alveolar ridge arch width and length were evaluated for their dimensional changes during the same age intervals.

Statistical Analysis Used

Mann-Whitney U-test was used to check the difference between the groups. The significance of the level adopted was 5%.

Results

Nasion-anterior nasal spine, anterior nasal spine-menton, anterior nasal spine-pterygomaxillary fissure, gonion-sella, and gonion-menton lengths were found to be not statistically significant than the mean standard values of nearly corresponding ages (P > 0.05). The decrease in facial plane angle, increase in Y-axis angle, and mandibular plane angle after complete denture rehabilitation were statistically significant when compared to their mean standard values (P < 0.05). Cast analysis showed more increase in the length compared to the width in both arches.

Conclusion

Complete denture rehabilitation did not significantly affect the jaw growth pattern, although it improved facial esthetics and masticatory activity by establishing adequate vertical dimensions.

Rare diseases of ectoderm: Translating discovery to therapy

Heritable conditions known as ectodermal dysplasias are rare and can be associated with marked morbidity, mortality, and a reduced quality of life. The diagnosis and care of individuals affected by one of the many ectodermal dysplasias presents myriad challenges due to their rarity and the diverse phenotypes. These conditions are caused by abnormalities in multiple genes and signaling pathways that are essential for the development and function of ectodermal derivatives. During a 2021 international conference focused on translating discovery to therapy, researchers and clinicians gathered with the goal of advancing the diagnosis and treatment of conditions affecting ectodermal tissues with an emphasis on skin, hair, tooth, and eye phenotypes. Conference participants presented a variety of promising treatment strategies including gene or protein replacement, gene editing, cell therapy, and the identification of druggable targets. Further, barriers that negatively influence the current development of novel therapeutics were identified. These barriers include a lack of accurate prevalence data for rare conditions, absence of an inclusive patient registry with deep phenotyping data, and insufficient animal models and cell lines. Overcoming these barriers will need to be prioritized in order to facilitate the development of novel treatments for genetic disorders of the ectoderm.

Dental Phenotype with Minor Ectodermal Symptoms Suggestive of WNT10A Deficiency

Ectodermal dysplasias (EDs) represent a heterogeneous group of genetic disorders characterized by the abnormal development of ectodermal-derived tissues. They include the involvement of the hair, nails, skin, sweat glands, and teeth. Pathogenic variants in EDA1 (Xq12-13.1; OMIM*300451), EDAR (2q11-q13; OMIM*604095), EDARADD (1q42-q43, OMIM*606603), and WNT10A (2q35; OMIM*606268) genes are responsible for most EDs. Bi-allelic pathogenic variants of WNT10A have been associated with autosomal recessive forms of ED, as well as non-syndromic tooth agenesis (NSTA). The potential phenotypic impact of associated modifier mutations in other ectodysplasin pathway genes has also been pointed out. We present on an 11-year-old Chinese boy with oligodontia, with conical-shaped teeth as the main phenotype, and other very mild ED signs. The genetic study identified the pathogenic variants WNT10A (NM_025216.3): c.310C > T; p. (Arg104Cys) and c.742C > T; p. (Arg248Ter) in compound heterozygosis, confirmed by parental segregation. In addition, the patient had the polymorphism EDAR (NM_022336.4): c.1109T > C, p. (Val370Ala) in homozygosis, named EDAR370. A prominent dental phenotype with minor ectodermal symptoms is very suggestive of WNT10A mutations. In this case, the EDAR370A allele might also attenuate the severity of other ED signs.

Further delineation of the CWC27-associated spliceosomeopathy: Case report and review of the literature

Pre-mRNA splicing factors are crucial in regulating transcript diversity, by removing introns from eukaryotic transcripts, an essential step in gene expression. Splicing of pre-mRNA is catalyzed by spliceosomes. CWC27 is a cyclophilin associated with spliceosome, in which genetic defects of its components have been linked to spliceosomopathies with clinical phenotypes including skeletal developmental defects, retinitis pigmentosa (RP), short stature, skeletal anomalies, and neurological disorders. We report two siblings (male and female) of Mexican descent with a novel homozygous frameshift variant in CWC27 and aim to highlight the cardinal features among the previously described 12 cases as well as expand the currently recognized phenotypic spectrum. Both siblings presented with a range of ocular and extraocular manifestations including novel features such as solitary kidney and tarsal coalition in the male sibling, together with gait abnormalities, and Hashimoto's thyroiditis in the female sibling. Finally, we highlight ectodermal involvement including sparse scalp hair, eyebrows and lashes, pigmentary differences, nail dysplasia, and dental anomalies as a core phenotype associated with the CWC27 spliceosomopathy.

Protocol for the Phase 2 EDELIFE Trial Investigating the Efficacy and Safety of Intra-Amniotic ER004 Administration to Male Subjects with X-Linked Hypohidrotic Ectodermal Dysplasia

X-linked hypohidrotic ectodermal dysplasia (XLHED) is a rare genetic disorder characte-rised by abnormal development of the skin and its appendages, such as hair and sweat glands, the teeth, and mucous glands of the airways, resulting in serious, sometimes life-threatening complications like hyperthermia or recurrent respiratory infections. It is caused by pathogenic variants of the ectodysplasin A gene (EDA). Most affected males are hemizygous for EDA null mutations that lead to the absence or inactivity of the signalling protein ectodysplasin A1 (EDA1) and, thus, to the full-blown phenotype with inability to perspire and few if any teeth. There are currently no long-term treatment options for XLHED. ER004 represents a first-in-class protein replacement molecule designed for specific, high-affinity binding to the endogenous EDA1 receptor (EDAR). Its proposed mechanism of action is the replacement of missing EDA1 in yet unborn patients with XLHED. Once bound to EDAR, ER004 activates the EDA/NFκB signalling pathway, which triggers the transcription of genes involved in the normal development of multiple tissues. Following preclinical studies, named-patient use cases demonstrated significant potential of ER004 in affected males treated in utero during the late second and third trimesters of pregnancy. In order to confirm these results, we started the EDELIFE trial, a prospective, open-label, genotype-match controlled, multicentre clinical study to investigate the efficacy and safety of intra-amniotic ER004 administration as a prenatal treatment for male subjects with XLHED. This article summarises the rationale, the study protocol, ethical issues of the trial, and potential pitfalls.

Peri-operative management of a patient with an ectodermal dysplasia (Rapp-Hodgkin) syndrome

We present the case of a 41-year-old man with Rapp-Hodgkin syndrome who underwent nasal septum deviation surgery under general anaesthesia. This syndrome is rare, with approximately 70 cases reported worldwide. It is one of a group of ectodermal dysplasia syndromes and results from the aberrant development of ectoderm during fetal development. Some of the clinical features may affect anaesthetic management. The most important considerations are potentially difficult airway management, the need for meticulous temperature control, and the importance of skin protection. This case was uneventful, but as there are few case reports on the management of patients with ectodermal dysplasia syndromes undergoing anaesthesia this report contributes useful knowledge. The pathogenesis and clinical features of Rapp-Hodgkin syndrome and the anaesthetic management for this patient are described.

Molecular Pathway-Based Classification of Ectodermal Dysplasias: First Five-Yearly Update

To keep pace with the rapid advancements in molecular genetics and rare diseases research, we have updated the list of ectodermal dysplasias based on the latest classification approach that was adopted in 2017 by an international panel of experts. For this purpose, we searched the databases PubMed and OMIM for the term "ectodermal dysplasia", referring mainly to changes in the last 5 years. We also tried to obtain information about those diseases on which the last scientific report appeared more than 15 years ago by contacting the authors of the most recent publication. A group of experts, composed of researchers who attended the 8th International Conference on Ectodermal Dysplasias and additional members of the previous classification panel, reviewed the proposed amendments and agreed on a final table listing all 49 currently known ectodermal dysplasias for which the molecular genetic basis has been clarified, including 15 new entities. A newly reported ectodermal dysplasia, linked to the gene LRP6, is described here in more detail. These ectodermal dysplasias, in the strict sense, should be distinguished from syndromes with features of ectodermal dysplasia that are related to genes extraneous to the currently known pathways involved in ectodermal development. The latter group consists of 34 syndromes which had been placed on the previous list of ectodermal dysplasias, but most if not all of them could actually be classified elsewhere. This update should streamline the classification of ectodermal dysplasias, provide guidance to the correct diagnosis of rare disease entities, and facilitate the identification of individuals who could benefit from novel treatment options.

Adams-Oliver syndrome and associated complications: Report of a family in Colombia and review of the literature

The Adams-Oliver syndrome is a rare congenital disorder characterized by aplasia cutis congenita of the scalp, terminal transverse limb defects, and congenital telangiectatic cutis marmorata. It can occur through different inheritance patterns: autosomal dominant, autosomal recessive, or de novo dominant mutations. Although the Adams-Oliver syndrome is a rare disease, it is essential to know its clinical characteristics and inheritance patterns, to establish a correct diagnosis and its possible complications during follow-up. In the present study, we describe the case of an adolescent with Adams-Oliver syndrome with an autosomal dominant inheritance pattern, pulmonary hypertension and plastic bronchitis, and several compromised family members.

Recording jaw relation of a pediatric patient with ectodermal dysplasia and complete anodontia using a digital mini arch tracer: A case report

Children with ectodermal dysplasia and complete anodontia experience difficulties in oral rehabilitation because of the small arch size. A case of a 7-year-old boy, whose arch size (length and width) was 30-40% smaller than that of a male adult and who presented with difficulties in jaw relation recording using commercially available devices is described. A digital workflow involving a mini arch tracer was introduced. Primary impressions were made using three-dimensionally (3D) printed mini trays produced based on the patient's computed tomography images, and digital primary casts were obtained based on the scanned and reversed primary impressions. The final custom impression trays with mini tracing plates were designed based on the primary casts. In addition, the hand shank, retention plate, and retainers were placed on the designed custom trays and 3D-printed to produce an individual arch tracer system. In addition, two height-checking buckles were designed to help adjust the height of a tracing screw. Finally, the jaw relation of the patient was recorded and transferred, and a set of complete dentures were delivered, satisfying both the patient and his family.

Ectodysplasin A1 Deficiency Leads to Osteopetrosis-like Changes in Bones of the Skull Associated with Diminished Osteoclastic Activity

Pathogenic variants of the gene Eda cause X-linked hypohidrotic ectodermal dysplasia (XLHED), which is characterized by structural abnormalities or lack of ectodermal appendages. Signs of dysplasia are not restricted to derivatives of the ectodermal layer, but mesodermal abnormalities, such as craniofacial dysmorphism, are also frequently observed, suggesting close reciprocal interactions between the ectoderm and mesoderm; however, a causal link has remained unsubstantiated. We investigated the functional impact of defective ectodysplasin A1 (Eda1) signaling on postnatal bone homeostasis in Eda1-deficient Tabby mice. Interestingly, Eda1 was detected in wild-type mouse calvariae throughout postnatal lifetime. In calvariae, bone-lining Osterix (Osx)+ osteoblasts stained positive for Eda1, and osteoclasts were revealed as Eda receptor (Edar)-positive. Moreover, adult Eda1-deficient calvarial bone showed osteopetrosis-like changes with significantly diminished marrow space, which was maintained during adulthood. Concomitantly with osteopetrosis-like changes, Tabby calvarial bone and Tabby bone marrow-derived osteoclasts had far less osteoclastic activity-associated co-enzymes including cathepsin K, Mmp9, Trap, and Tcirg1 (V-type proton ATPase a3 subunit) compared with wild-type calvariae in vivo or osteoclasts in vitro, indicating that Eda1 deficiency may affect the activity of osteoclasts. Finally, we confirmed that nuclear Nfatc1-positive osteoclasts were strongly diminished during mature osteoclastic differentiation under M-CSF and RANKL in the Tabby model, while Fc-EDA treatment of Tabby-derived osteoclasts significantly increased nuclear translocation of Nfatc1. Furthermore, we identified enhanced Nfatc1 and NF-κB transcriptional activity following Fc-EDA treatment in vitro using luciferase assays. Overall, the results indicate that diminished expressions of osteoclastic activity-associated co-enzymes may lead to disturbed bone homeostasis in Tabby calvariae postnatally.

Confirmation of a Phenotypic Entity for TSPEAR Variants in Egyptian Ectodermal Dysplasia Patients and Role of Ethnicity

Ectodermal dysplasia (ED) are hereditary disorders characterized by the disturbance of the ectodermal development of at least two of four ectodermal tissues: teeth, hair, nails and sweat glands. Clinical classification of ED is challenged by overlapping features, variable expressivity, and low number of patients, hindering full phenotypic spectrum identification. Disease-causing variants in elements of major developmental pathways, e.g., Ectodysplasin/NFκB, Wnt, and Tp63 pathways, have been identified in fewer than half of ED phenotypes. Whole-exome sequencing (WES) was performed for ten Egyptian ED patients presenting with tooth agenesis, normal sweating, scalp hypotrichosis, and sharing characteristic facial features. WES was followed by in silico analysis of the effects of novel detected genetic variants on mRNA and protein structure. The study identified four novel rare pathogenic and likely pathogenic TSPEAR variants, a gene which was recently found to be involved in ectodermal organogenesis. A novel in-frame deletion recurred in eight patients from six unrelated families. Comparing our cohort to previously reported TSPEAR cohorts highlighted the influence of ethnicity on TSPEAR phenotypic affection. Our study expands the clinical and mutational spectrum of the growing TSPEAR associated phenotypes, and pinpoints the influence of WES and in silico tools on identification of rare disease-causing variants.

A Rare Case of Hypohidrotic Ectodermal Dysplasia in a Seven-Year-Old Child

Ectodermal dysplasias (EDs) encompass a large group of inherited disorders that affects two or more ectodermally derived structures. Hair, sweat glands, teeth, and nails are the most common ectodermal derivates affected. Other ectodermal structures that may be affected are ears, eyes, lips, and mucous membranes of the mouth or nose. During embryonic development, the ectoderm forms the outermost layer of the primary germ layers that give rise to the several structures that are commonly affected in ED. Therefore, ED manifests differently among patients, depending on the abnormality's combination and severity. Out of 150 distinctive syndromes, the most common syndromes within this group are hypohidrotic (defective sweat glands) and hidrotic (normal sweat glands). In addition, different types of inheritance patterns are found in ED; X-linked inheritance is by far the most common mode of inheritance. We present here the clinical case of hypohidrotic (anhidrotic) ED in a seven-year-old boy.

Ectodermal Dysplasia: A Case Report

Ectodermal dysplasia (ED) is a hereditary genetic disorder that manifests a variety of deformities in one or more of the ectodermal derivatives. Ectodermal derivatives originate from ectodermal layers during embryonic development, such as skin, nails, hair, teeth, and exocrine glands. Over 150 variants of ED are reported in the literature. It has an incidence of seven in every 100,000 live births. There are two types of ED, which are hypohidrotic (anhidrotic) and hydrotic. The types are classified according to the degree of function of the sweat glands. This report discusses the case of a 13-month-old Saudi girl with typical features of ectodermal dysplasia who presented to a dermatology clinic.

Skin and Mucosal Manifestations in NEMO Syndrome: A Case Series and Literature Review

OBJECTIVES

To characterize the skin and mucosal findings of NEMO syndrome.

METHODS

Retrospective review of clinical characteristics from a cohort of two families with mutations in IKBKG (the NEMO-encoding gene). A literature review identified 86 studies describing 192 patients with IKBKG mutations whose data were also included.

SETTING

Single center with literature review.

PARTICIPANTS

Patients with mutations in IKBKG from our center and reported in the literature.

MAIN OUTCOMES AND MEASURES

Skin and mucosal characteristics of patients with NEMO syndrome.

RESULTS

In addition to ectodermal dysplasia and recurrent infections, male patients had findings of ichthyosis, palmoplantar keratoderma, and inflammatory skin diseases. Both male and female patients had mucocutaneous ulcers and slow-to-heal chronic wounds. In combination with patients from the literature, 59% (85/144) of males had ectodermal dysplasia with anhidrosis (EDA) features, and 8% and 10% (12/144; 6/63) of males and females had dental findings, respectively. 4% (6/144) of males and 32% (20/63) of females had mucocutaneous ulcers. Ichthyosis/xerosis was present in 15% of males (21/144) but only 2% (1/63) females. Similarly, 13% (18/144) of male patients presented with dermatitis while this was reported in only 2% (1/63) of females.

CONCLUSIONS

Our results both confirm and expand upon the known spectrum of mucocutaneous findings in NEMO syndrome. Further genetic studies are needed to correlate specific mutations to clinical and morphologic subtypes.

Rehabilitation of ectodermal dysplasia patient with a telescopic denture in the maxilla and mandibular implant assisted overdenture: A case report

Hypohidrotic ectodermal dysplasia is a heritable disease, characterized by hypodontia, hypotrichosis, and anhidrosis. This clinical report demonstrates prosthetic rehabilitation of a patient complaining of impaired mastication and the odd appearance of her jaws. Maxillary telescopic overdenture and implant-supported mandibular prostheses were fabricated to improve mastication, speech, and esthetics of the patient.

ANOTHER syndrome-Familial presentations of progressive lung disease leading to double lung transplantation: A case report and literature review

Ectodermal dysplasias (EDs) are a heterogeneous rare group of disorders with an incidence at 1/100,000 live births. Currently, there are limited case reports of patients requiring lung transplantation. Here, we report two brothers who present with a constellation of features including alopecia, nail dystrophy, ophthalmic complications, thyroid disease, hypohidrosis, ephelides, enteropathy and recurrent respiratory tract infections, known as ANOTHER syndrome, a rare autosomal recessive variant of ED. Both presented in early childhood with progressive respiratory decline and eventual failure. Chronic respiratory decline was refractory to standard therapy. Both patients required lung transplantation for sequelae of end-stage lung disease. Pathology demonstrated multifocal bronchiectasis with areas of fibrosis and small airway obstruction. ANOTHER syndrome is rare with a paucity of data in the literature. Given the limited therapeutic options available with natural progression towards respiratory failure, lung transplantation may be considered.

Dimensional Changes in Dental Arches after Complete Dentures Rehabilitation of a Patient with Hypohidrotic Ectodermal Dysplasia: A Case Report with 18-Year Follow-Up

BACKGROUND

This case report presents the dimensional changes in dental arches in a patient with hypohidrotic ectodermal dysplasia (HED) after complete denture rehabilitation, with an 18-year follow-up period.

CASE REPORT

The patient had complete anodontia and was successfully rehabilitated with conventional complete dentures at 3, 4, 5, 7, 9, 12, 16, and 21 years of age. Each successive denture was larger and contained more and larger teeth so as to accommodate for the increase in the size of the developing jaw. A series of diagnostic casts were used to measure the dimensional changes in the arch length and width of the alveolar ridge. Cast analysis revealed that there was an increase in arch length and width in both the maxilla and mandible over time. Cephalometric analysis of craniofacial development was performed at 21 years of age, and suggested protrusion of the maxilla and mandible.

CONCLUSIONS

The absence of teeth due to HED did not affect the dimensional changes in dental arches after complete denture rehabilitation from childhood to adulthood. The prosthetic treatment improved the patient's social integration and enabled the development of normal dietary habits, speech, and facial esthetics, which in turn led to improved quality of life.

Update of recent findings in genetic hair disorders

Genetic hair disorders, although unusual, are not very rare, and dermatologists often have opportunities to see patients. Significant advances in molecular genetics have led to identifying many causative genes for genetic hair disorders, including the recently identified causative genes, such as LSS and C3ORF52. Many patients have been detected with autosomal recessive woolly hair/hypotrichosis in the Japanese population caused by founder mutations in the LIPH gene. Additionally, many patients with genetic hair disorders caused by other genes have been reported in East Asia including Japan. Understanding genetic hair disorders is essential for dermatologists, and the findings obtained from analyzing these diseases will contribute to revealing the mechanisms of hair follicle morphogenesis and development in humans.

Correction of Vertebral Bone Development in Ectodysplasin A1-Deficient Mice by Prenatal Treatment With a Replacement Protein

X-linked hypohidrotic ectodermal dysplasia with the cardinal symptoms hypodontia, hypotrichosis and hypohidrosis is caused by a genetic deficiency of ectodysplasin A1 (EDA1). Prenatal EDA1 replacement can rescue the development of skin appendages and teeth. Tabby mice, a natural animal model of EDA1 deficiency, additionally feature a striking kink of the tail, the cause of which has remained unclear. We studied the origin of this phenomenon and its response to prenatal therapy. Alterations in the distal spine could be noticed soon after birth, and kinks were present in all Tabby mice by the age of 4 months. Although their vertebral bones frequently had a disorganized epiphyseal zone possibly predisposing to fractures, cortical bone density was only reduced in vertebrae of older Tabby mice and even increased in their tibiae. Different availability of osteoclasts in the spine, which may affect bone density, was ruled out by osteoclast staining. The absence of hair follicles, a well-known niche of epidermal stem cells, and much lower bromodeoxyuridine uptake in the tail skin of 9-day-old Tabby mice rather suggest the kink being due to a skin proliferation defect that prevents the skin from growing as fast as the skeleton, so that caudal vertebrae may be squeezed and bent by a lack of skin. Early postnatal treatment with EDA1 leading to delayed hair follicle formation attenuated the kink, but did not prevent it. Tabby mice born after prenatal administration of EDA1, however, showed normal tail skin proliferation, no signs of kinking and, interestingly, a normalized vertebral bone density. Thus, our data prove the causal relationship between EDA1 deficiency and kinky tails and indicate that hair follicles are required for murine tail skin to grow fast enough. Disturbed bone development appears to be partially pre-determined in utero and can be counteracted by timely EDA1 replacement, pointing to a role of EDA1 also in osteogenesis.

Rare Genetic Disorders: Novel Treatment Strategies and Insights Into Human Biology

The last decade has seen a dramatic increase in innovative ideas for the treatment of genetic disorders for which no curative therapies exist. Gene and protein replacement therapies stand out as novel approaches to treat a select group of these diseases, such as certain tissue fragility disorders. Further, the advent of stem cell approaches, such as induced pluripotent stem cells (iPSC) technology, has led to the development of new methods of creating replacement tissues for regenerative medicine. This coincided with the discovery of genome editing techniques, which allow for the correction of disease-causing mutations. The culmination of these discoveries suggests that new and innovative therapies for monogenetic disorders affecting single organs or tissues are on the horizon. Challenges remain, however, especially with diseases that simultaneously affect several tissues and organs during development. Examples of this group of diseases include ectodermal dysplasias, genetic disorders affecting the development of tissues and organs such as the skin, cornea, and epithelial appendages. Gene or protein replacement strategies are unlikely to be successful in addressing the multiorgan phenotype of these diseases. Instead, we believe that a more effective approach will be to focus on correcting phenotypes in the most severely affected tissues. This could include the generation of replacement tissues or the identification of pharmaceutical compounds that correct disease pathways in specific tissues.

Innovative tooth-colored CAD/CAM polycarbonate splint design for prosthetic rehabilitation of a young ectodermal dysplasia patient with permanent tooth aplasia

Ectodermal dysplasia (ED) is one of the congenitally syndromic diseases with dental anomalies. This syndrome manifests in various forms and usually requires early restorative therapy to restore esthetics and function in young patients. The restorative approaches vary greatly and range from minimally invasive shape corrections using composite build-ups and removable partial or complete dental prostheses, to implantologic solutions, always based on the syndromic expression, the age of the patient, the residual growth, as well as the dentition itself. The present case report presents an innovative prosthetic management of a young patient suffering from ED with permanent tooth aplasia and persistent primary teeth using maxillomandibular individually veneered tooth-colored CAD/CAM polycarbonate splints. The CAD phase has been significantly improved by including the analysis of 3D face scans. This advanced technical development makes it possible to avoid any time-consuming try-in and start directly with the splint production, ensuring a much faster complete rehabilitation and support for the young patient.

Late-onset eccrine syringofibroadenoma of the feet in a patient with hypohidrotic ectodermal dysplasia

A 56-year-old woman with hypohidrotic ectodermal dysplasia presented with a 10-year history of persisting wart-like skin lesions on her feet. Biopsy revealed changes of eccrine syringofibroadenoma. These lesions are rare, with only nine case reports describing an association with ectodermal dysplasia of hidrotic type (Clouston and Schopf's syndrome). To our knowledge, this is the first case of eccrine syringofibroadenoma developing in the hypohidrotic/anhidrotic subtype of ectodermal dysplasia.

TSPEAR variants are primarily associated with ectodermal dysplasia and tooth agenesis but not hearing loss: A novel cohort study

Biallelic loss‐of‐function variants in the thrombospondin‐type laminin G domain and epilepsy‐associated repeats (TSPEAR) gene have recently been associated with ectodermal dysplasia and hearing loss. The first reports describing a TSPEAR disease association identified this gene is a cause of nonsyndromic hearing loss, but subsequent reports involving additional affected families have questioned this evidence and suggested a stronger association with ectodermal dysplasia. To clarify genotype–phenotype associations for TSPEAR variants, we characterized 13 individuals with biallelic TSPEAR variants. Individuals underwent either exome sequencing or panel‐based genetic testing. Nearly all of these newly reported individuals (11/13) have phenotypes that include tooth agenesis or ectodermal dysplasia, while three newly reported individuals have hearing loss. Of the individuals displaying hearing loss, all have additional variants in other hearing‐loss‐associated genes, specifically TMPRSS3, GJB2, and GJB6, that present competing candidates for their hearing loss phenotype. When presented alongside previous reports, the overall evidence supports the association of TSPEAR variants with ectodermal dysplasia and tooth agenesis features but creates significant doubt as to whether TSPEAR variants are a monogenic cause of hearing loss. Further functional evidence is needed to evaluate this phenotypic association.

Ectodermal Dysplasia-Syndactyly Syndrome with Toe-Only Minimal Syndactyly Due to a Novel Mutation in NECTIN4: A Case Report and Literature Review

Ectodermal dysplasia-syndactyly syndrome 1 (EDSS1) is characterized by cutaneous syndactyly of the toes and fingers and abnormalities of the hair and teeth, variably associated with nail dystrophy and palmoplantar keratoderma (PPK). EDSS1 is caused by biallelic mutations in the NECTIN4 gene, encoding the adherens junction component nectin-4. Nine EDSS1 cases have been described to date. We report a 5.5-year-old female child affected with EDSS1 due to the novel homozygous frameshift mutation c.1150delC (p.Gln384ArgfsTer7) in the NECTIN4 gene. The patient presents brittle scalp hair, sparse eyebrows and eyelashes, widely spaced conical teeth and dental agenesis, as well as toenail dystrophy and mild PPK. She has minimal proximal syndactyly limited to toes 2-3, which makes the phenotype of our patient peculiar as the overt involvement of both fingers and toes is typical of EDSS1. All previously described mutations are located in the nectin-4 extracellular portion, whereas p.Gln384ArgfsTer7 occurs within the cytoplasmic domain of the protein. This mutation is predicted to affect the interaction with afadin, suggesting that impaired afadin activation is sufficient to determine EDSS1. Our case, which represents the first report of a NECTIN4 mutation with toe-only minimal syndactyly, expands the phenotypic and molecular spectrum of EDSS1.

De novo filament formation by human hair keratins K85 and K35 follows a filament development pattern distinct from cytokeratin filament networks

In human hair follicles, the hair‐forming cells express 16 hair keratin genes depending on the differentiation stages. K85 and K35 are the first hair keratins expressed in cortical cells at the early stage of the differentiation. Two types of mutations in the gene encoding K85 are associated with ectodermal dysplasia of hair and nail type. Here, we transfected cultured SW‐13 cells with human K85 and K35 genes and characterized filament formation. The K85–K35 pair formed short filaments in the cytoplasm, which gradually elongated and became thicker and entangled around the nucleus, indicating that K85–K35 promotes lateral association of short intermediate filaments (IFs) into bundles but cannot form IF networks in the cytoplasm. Of the K85 mutations related to ectodermal dysplasia of hair and nail type, a two‐nucleotide (C¹⁴⁴⁸T¹⁴⁴⁹) deletion (delCT) in the protein tail domain of K85 interfered with the K85–K35 filament formation and gave only aggregates, whereas a missense mutation (233A>G) that replaces Arg⁷⁸ with His (R78H) in the head domain of K85 did not interfere with the filament formation. Transfection of cultured MCF‐7 cells with all the hair keratin gene combinations, K85–K35, K85(R78H)–K35 and K85(delCT)–K35, as well as the individual hair keratin genes, formed well‐developed cytoplasmic IF networks, probably by incorporating into the endogenous cytokeratin IF networks. Thus, the unique de novo assembly properties of the K85–K35 pair might play a key role in the early stage of hair formation.